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Hepatic angiosarcomas are aggressive malignant tumors of the liver with variable morphology. One of the rare morphologies is that of the sinusoidal growth pattern, which is challenging to diagnose because of its subtle imaging and morphologic findings. This retrospective study characterizes the clinical, histologic, and immunohistochemical features of sinusoidal hepatic angiosarcomas. Thirteen cases were included in the study, comprising 12 (92.3%) needle core biopsies and 1 wedge biopsy; one of the needle biopsies also had a subsequent resection specimen available for review. Multiple biopsies were needed to make the diagnosis in 4 cases. At least moderate sinusoidal dilatation was seen in 53.8% of cases. Increased cellularity within the sinusoids was seen at both low-power and high-power magnification (69.2% and 84.6%, respectively). Cytologic atypia ranged from mild to marked. Multinucleated tumor cells were present in most cases (10/13 cases) but were often sparse. Mitotic activity was identified in 5/13 cases. ERG immunostains were more reliable than CD31 and CD34 in identifying the tumor cells. Ki-67 proliferative index ranged from 5% to 30%. p53 immunostains were available in 9 cases and c-MYC in 7 cases; they were positive in 62.5% and 33.3% of cases, respectively and had a mutually exclusive staining pattern. In summary, this rare pattern of hepatic angiosarcoma is challenging to diagnose but has distinctive morphologic findings that can be supplemented with immunostains to establish the diagnosis., Competing Interests: Conflicts of Interest and Source of Funding: Supported by a P50 CA210964 grant (M.S.T.). The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Despite a wide spectrum of clinical presentations, including primary or secondary, most angiosarcomas are considered high grade. One exception is primary breast angiosarcoma, where historically, histologic grading has shown to predict outcome using the Rosen 3-tier system. However, more recent studies have challenged this concept suggesting that even in this specific clinical context angiosarcomas should be considered high grade. This study aimed to critically reevaluate the impact of histologic grade in a clinically uniform cohort managed at a single institution using a newly proposed grading system. Our study included 49 primary breast angiosarcomas diagnosed during 1994 to 2022 (median follow-up: 33 mo), classified as low grade (29%), intermediate grade (20%), and high grade (51%), based on mitotic count, extent of solid components, and necrosis. At last follow-up, 22% patients developed locoregional recurrences, 63% distant metastases, and 47% patients died of disease. As patients with low and intermediate-grade angiosarcomas had relatively similar outcomes, our cohort was further analyzed using a 2-tier system (low grade and high grade). Targeted-DNA next-generation sequencing (505 cancer gene panel) performed in 11 cases found KDR mutations in 78% and PIK3CA mutations in 44% of high-grade lesions. Histologic grade, by either 3-tier or 2-tier grading systems, had a strong impact on survival, with the 2-tier system being an independent predictor of disease-specific survival and overall survival. Based on 2-tier system, the 5-year overall survival was 38% for high-grade angiosarcoma and 74% for low-grade angiosarcoma. PIK3CA mutations alone or concurrent with KDR alterations were identified in angiosarcomas with worse prognosis., Competing Interests: Conflicts of Interest and Source of Funding: Funded in part through the NIH/NCI Cancer Center Support Grant P30 CA008748 (all authors), P50 CA217694 (C.R.A.), Cycle for Survival (C.R.A.), and Angiosarcoma Awareness (C.R.A.). The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

We report 55 postchemotherapy resections of primary nonseminomatous mediastinal germ cell tumors with prominent vasculogenic features showing the formation of rudimentary to well-developed neoplastic vessels within primitive mesenchyme. These cases represented 25% of a cohort of 221 such specimens. The patients were 19 to 49 years old (mean, 28 y) and 98% had serological evidence of yolk sac tumor. The vasculogenic lesions, felt to represent a neoplastic reiteration of embryonic vasculogenesis in the splanchnic mesoderm of the yolk sac, were further subdivided into teratoma with vasculogenic stroma (n=9), vasculogenic mesenchymal tumor (VMT) (n=42, further classified into low grade [n=24] and high grade [n=18]), and angiosarcoma (n=4). The distinction of teratoma with vasculogenic stroma from VMT was based solely on the greater extent of VMT (exceeding 1 low power [×4 objective] microscopic field), with both categories showing a spectrum of vessels lined by atypical endothelium in a nonendothelial neoplastic stroma that often also generated vascular walls comprised of atypical smooth muscle. The angiosarcomas showed stratification of highly atypical endothelial cells or anastomosing vessels lined by nonstratified but cytologically similar endothelium. Immunohistochemical studies supported the generation of neoplastic vessels from the tumor stroma, most commonly by the development of stromal clefts showing reactivity for podoplanin, CD34, and occasionally ERG, followed by the gradual development from the clefts of thin-walled vessels that later became encircled by stromal cells showing smooth muscle differentiation by immunohistochemistry. Occasionally, round collections of stromal erythrocytes became surrounded by stromal cells to generate blood vessels. Fluorescence in situ hybridization showed chromosome 12p copy number increase in both the endothelial component and stromal component in 8/9 VMT cases and in 1/1 angiosarcoma. On follow-up, no patient with teratoma with vasculogenic stroma had evidence of a subsequent vascular tumor or sarcoma, whereas 8 of the 35 (23%) patients with VMTs (2 low grade and 6 high grade) and meaningful follow-up developed sarcoma (1 angiosarcoma, 2 rhabdomyosarcomas, and 5 not further characterized). The difference between low-grade and high-grade tumors was of borderline significance (P=0.058). Two of the 4 patients with angiosarcoma died of metastatic angiosarcoma, with the other 2 disease-free at 6.8 and 7 years. Compared with the 165 patients with follow-up and no vasculogenic lesions, there was a highly significant (P=4.3×10-5) association of any vasculogenic lesion with sarcomatoid tumors during the clinical course of VMT patients. In addition, 5/46 patients with follow-up and vasculogenic lesions (11%) died of either leukemia or myelodysplastic syndrome compared with 2 of 166 (1%) lacking them (P=0.0012). Three of the 5 patients had identifiable immature hematopoietic cells within their vasculogenic lesions, but 4 other VMT patients with these did not develop leukemia or myelodysplasia. We conclude: (1) vasculogenic lesions are frequent in postchemotherapy resections of primary mediastinal germ cell tumors with yolk sac tumor components; (2) they mostly consist of neoplastic vessels in a stroma that also generates neoplastic vascular walls of smooth muscle; (3) VMTs are associated with an increased incidence of sarcomas, even though most vasculogenic lesions in this context do not meet criteria for angiosarcoma; (4) the presence of vasculogenic lesions in postchemotherapy resections of primary mediastinal germ cell tumors place patients at increased risk for leukemia or myelodysplasia., Competing Interests: Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

We report 21 cases of a distinctive and unique vascular tumor which we propose to be a pure lymphatic-type angiosarcoma characterized by architectural and growth characteristics of angiosarcoma, cytologic, and immunohistochemical features of lymphatic differentiation, a prominent lymphocytic infiltrate, and variable nuclear grade. Patients included 12 males and 9 females with a median age of 65 years (range: 32 to 95 y). Tumors involved the head and neck (n=11), lower extremities (n=5), trunk (n=4), and upper extremity (n=1) and were located superficially in the dermis and/or subcutis. Tumors were designated "low grade" (n=10) when the nuclear grade was low, and vascular channel formation was evident throughout but with multilayering of endothelium within the vessels. Cases were designated "high grade" (n=11) when nuclei appeared higher grade with more rounded contours and prominent nucleoli and when solid areas predominated over vascular channel formation. A striking feature of both groups was the presence of a dense, lymphocytic infiltrate with occasional germinal center formation. All cases strongly and diffusely expressed at least 1 lymphatic marker (21/21) with podoplanin (17/19) and Prox-1 (11/11) more commonly expressed than LYVE-1 (5/10). No consistent molecular alteration was identified. Follow-up on 17 patients (median: 41 mo, mean: 54 mo) showed 10 patients were alive without disease, 5 were alive with disease, 1 died of other cause, and 1 died of disease. Local recurrence developed in 9 cases and metastasis in 2 cases, although neither correlated with grade as defined. On the basis of clinical follow-up to date, the natural history of lymphatic-type angiosarcoma appears to be more favorable than other forms of cutaneous angiosarcoma.

Background: Cutaneous angiosarcoma (cAS) is a highly aggressive malignancy that challenges the radicality of surgical treatment. Electrochemotherapy (ECT), a skin-directed treatment based on cytotoxic chemotherapy combined with local electric pulses, may be an intraoperative adjunct and a new opportunity in the therapeutic strategy. This cohort study reports the experience with ECT as an option., Methods: Data on patients with locally-advanced/metastatic cAS who underwent ECT between October 2013 and October 2018 at eight European centres were prospectively submitted to the InspECT (International network for sharing practices of ECT) register. Patients received therapy according to the European Standard Operating Procedures of ECT (ESOPE). Treatment feasibility was assessed based on tumour coverage with electrodes and recorded tissue current; treatment toxicity and tumour response were graded according to CTCAE v5.0 and RECIST v1.1 criteria, respectively; patient-reported outcomes (PRO) were evaluated using a visual analogue score (VAS) for pain, acceptance of retreatment and the EQ-5D questionnaire., Results: We enrolled 20 patients with advanced cAS in the scalp/face (n = 7), breast/trunk (n = 10) or limbs (n = 3). Target tumours (n = 51) had a median size of 2.3 cm (range, 1-20). We administered 24 ECT courses using 1-4 cm treatment safety margin around tumours. In five patients, ECT was combined/sequenced with surgery. Median tissue current was 3 A (range, 1.5-10), tumour margins coverage rate was 75% (15/20 patients). The objective response rate (ORR) was 80% (complete, 40%). Grade-3 toxicity included skin ulceration (15%) and pain (10%), with no significant change of PRO scores. Bleeding control was achieved in 13/14 patients with ulcerated tumours. With a median overall survival of 12.5 months, the local progression-free survival (LPFS) was 10.9 months., Conclusion: ECT produces sustained response rate with minimal side effects and should be considered an option for advanced cAS. Palliative benefits include patient tolerability, local haemostasis and durable local control. Definition of optimal timing, treatment safety margins and combination with surgery need further investigation., (Copyright © 2019 IJS Publishing Group Ltd. Published by Elsevier Ltd. All rights reserved.)

Angiosarcoma is a rare malignant neoplasm of the liver. The various morphologic patterns seen with angiosarcomas of the liver have not been systematically studied and their recognition remains a major diagnostic challenge. In order to provide more comprehensive data on the morphologic patterns, angiosarcomas that had been diagnosed between 1996 and 2016 at a large medical referral center were reviewed. The major growth patterns were classified as sinusoidal (non-mass forming) versus mass forming. The mass-forming cases were further subdivided into epithelioid, spindled, or vasoformative. The study identified 21 patients with primary hepatic angiosarcoma: 13 men and 8 women. The ages ranged from 26 to 89 years. Seventeen angiosarcomas were mass-forming tumors, of which 9 showed predominantly vasoformative growth. Most of these vasoformative cases (6/9) were composed of small vessels, 2 cases had slit-like vascular spaces, and one case showed a mixture of small and large vessels. There were 7 mass-forming angiosarcomas without vasoformation: 3 had an epithelioid morphology and 4 were composed primarily of spindled cells. The final mass-forming tumor showed a mixture of vasoformative and nonvasoformative areas. Four of 21 cases were non-mass forming and showed either diffuse sinusoidal infiltration (N=2) or prominent peliotic changes (N=2). Finally, 3 uncommon patterns were identified. One case showed nodules of spindle cells arranged in prominent whorls in a background of loose connective tissue with abundant inflammation. A second case arose in the setting of the Blue Rubber Bleb Nevus Syndrome and showed numerous tumor nodules with an architectural pattern that resembled infantile hemangioma, some with areas of atypia consistent with malignant transformation to angiosarcoma. The third unusual pattern showed multiple nodules of thin walled large caliber vascular proliferations, some of which showed atypia that reached the level of angiosarcoma. The results from this study indicate that the majority of hepatic angiosarcomas are mass forming (two third of cases), a pattern that is recognizable on H&E when vasoformative, but can mimic carcinoma or undifferentatied sarcomas when nonvasoformative (one third of cases). The sinusoidal patterns are particularly challenging and are frequently missed on initial review. Finally, we describe several unsual patterns of angiosarcoma. Awareness of these classic and rare morphologic patterns can help make the diagnosis of angiosarcoma.

Angiosarcoma (AS) is a rare sarcoma subtype showing considerable clinicopathologic and genetic heterogeneity. Most radiation-induced AS show MYC gene amplifications, with a subset of cases harboring KDR, PTPRB, and PLCG1 mutations. Despite recent advances, the genetic abnormalities of most primary AS remain undefined. Whole-transcriptome sequencing was initiated in 2 index cases of primary soft tissue AS with epithelioid morphology occurring in young adults for novel gene discovery. The candidate abnormalities were validated and then screened by targeted sequencing and fluorescence in situ hybridization in a large cohort of 120 well-characterized AS cases. Findings were subsequently correlated with the status of KDR, PLCG1, MYC, and FLT4 gene abnormalities. The clinicopathologic relevance and prognostic significance of these genetic changes were analyzed by statistical methods. Concurrent CIC mutations and CIC rearrangements were identified in both index cases, with a CIC-LEUTX fusion detected in 1 case. Upon screening, an additional visceral AS in a young adult had a complex CIC rearrangement, whereas 6 others harbored only CIC mutations. All 3 CIC-rearranged AS cases lacked vasoformation and had a solid growth of round, epithelioid to rhabdoid cells, showing immunoreactivity for CD31 and Ets-related gene and sharing a transcriptional signature with other round cell sarcomas, including CIC-rearranged tumors. Overall, CIC abnormalities occurred in 9% (9/98) of cases, affecting younger patients with primary AS, with an inferior disease-free survival. In contrast, PLCG1 and KDR mutations occurred in both primary and secondary AS cases, accounting for 9.5% and 7%, respectively, with a predilection for breast and bone/viscera location, regardless of MYC status. MYC amplification was present in most secondary AS related to breast cancer (91%) compared with other causes (25%) or primary AS (7%). FLT4-amplified AS lacked PLCG1/KDR mutations, occurring predominantly in MYC-amplified population, and showed poor prognosis.

Primary angiosarcoma of the bladder is very rare, with approximately 30 cases reported in the literature. Those with epithelioid morphology are even rarer, with only single-case reports published. We describe the histopathologic features and clinical follow-up of 9 patients with epithelioid angiosarcoma (EA) of the bladder retrieved from our Surgical Pathology files from 1998 to 2014. Eight cases were consults. The mean age at presentation was 65 years (range, 39 to 85 y). The M:F ratio was 8:1. The clinical presentation was hematuria and bladder mass in all cases. Six patients had a history of radiotherapy to the pelvis, 5 to treat prostate cancer and 1 to treat uterine cervical cancer. The time from radiotherapy to the diagnosis of EA ranged from 6 to 15 years. The average size of the tumor was 4 cm. (range, 1 to 8 cm.). The submitting diagnoses were poorly differentiated carcinoma (n=5), high-grade invasive urothelial carcinoma (n=3), and atypical vascular proliferation (n=1). Morphologically, the tumors were composed of nests and sheets of highly atypical cells with high nuclear to cytoplasmic ratio, occasional intracytoplasmic lumens, and a hemorrhagic background. None of the cases showed any urothelial carcinoma component. Three patients showed in addition usual angiosarcoma in the resection specimen. By immunohistochemistry, 5/9 cases were positive for cytokeratins, including CK7 (n=3), AE1/AE3 (n=3), and Cam5.2 (n=1). All cases were positive for at least 1 endothelial marker, including CD31 (n=7), CD34 (n=2), FVIII (n=3), and ERG (n=2). Urothelial markers (p63 and GATA3) were consistently negative. Surgical treatment included transurethral resection of the bladder (TURB) only (n=5), TURB followed by cystoprostatectomy (n=2), TURB followed by partial cystectomy (n=1), and cystoprostatectomy only (n=1). The tumor involved the muscularis propria in 5/9 patients, the periureteric adipose tissue in 1 patient, and the prostate and seminal vesicles in 1 patient. Five of 9 patients died of disease, with a median survival of 7 months (range, 6 to 14 mo). Two patients were alive with disease at 3 and 6 months of follow-up. One patient who underwent radical cystoprostatectomy was alive with no evidence of disease 12 months after surgery. EA of the bladder is a rare malignancy that is frequently misdiagnosed as high-grade carcinoma, especially due to positive immunostaining for cytokeratins. This tumor is more frequent in older men with a history of radiotherapy to the pelvis. Morphologic features that should suggest the vascular origin of the tumor include highly atypical nuclei with interspersed erythrocytes, hemorrhagic background, and occasional intracytoplasmic lumens. Patients usually present with muscle invasive disease, and the prognosis is dismal.

Malignant thoracic epithelioid vascular tumors are an uncommon and heterogenous group of tumors that include low-grade to intermediate-grade epithelioid hemangioendothelioma (EHE) and high-grade epithelioid angiosarcoma (EAS). We examine the morphologic and immunohistochemical features of 52 malignant epithelioid vascular tumors (10 low-grade EHE, 29 intermediate-grade EHE, and 13 EAS) involving the thorax (lung, pleura, mediastinum, heart, great vessels) including cases with exclusively thoracic disease (35) and with multiorgan disease including the thorax (17). Intermediate-grade EHE differs from low-grade EHE by the presence of necrosis, increased mitotic activity, and increased atypia. Morphologic features such as intranuclear inclusions, intracytoplasmic vacuoles, and stromal changes (chondroid, myxoid, or hyalinized stroma) are seen more frequently in EHE, whereas blood lakes, proliferation of slit-like vessels, and prominent nucleoli favor EAS. Fluorescence in situ hybridization analysis showed CAMTA1-WWTR1 fusions in 4/7 low-grade and 23/23 intermediate-grade EHE (P<0.001). In EAS, CAMTA1 rearrangement was negative in all cases, whereas a WWTR1 complex abnormality was found in 1/5 cases (P<0.001). This offers an objective means of differentiating intermediate-grade EHE from EAS, especially on limited biopsies. All cases show expression of at least 1 vascular marker, which allows differentiation from primary thoracic epithelial malignancies, although keratin expression is a potential pitfall with 29% of EHE and 25% of EAS showing keratin expression. Survival analysis shows that higher tumor grade for all tumors (P=0.026) as well as lung and pleural tumors only (P=0.010) and the presence of pleural involvement in lung and/or pleural tumors (P=0.042) correlate with poor prognosis.

The pseudoangiosarcomatous pattern has been described mostly in cutaneous and some visceral squamous cell carcinomas and is unique for its striking morphologic resemblance to angiosarcoma. Herein, we describe the clinicopathologic features of 7 pseudoangiosarcomatous urothelial carcinomas that occurred in the urinary bladder. The patients included 6 men and 1 woman ranging in age from 47 to 87 years (median 70 y). The pseudoangiosarcomatous morphology was observed in 7 urothelial carcinomas including 3 with squamous differentiation and comprised 35% to 85% of the invasive tumor. Histologically, the pseudoangiosarcomatous carcinomas were characterized by tumor cell discohesion and lysis that created pseudolumina formations surrounded by attached residual tumor cells. Detached degenerating tumor cells variably admixed with inflammatory cells were common in the false lumina. Partly intact urothelial carcinoma nests contained irregular or cleft-like spaces and disintegrating tumor cells with stretched intercellular bridges. The tumor was commonly associated with a dense collagenous matrix, often surrounding the lytic nests. Similar tumor cell discohesion and breakdown were observed in 3 tumors with foci of squamous cell differentiation, distinguished by the presence of dyskeratosis and keratin formation. All 7 tumors contained other nonpseudoangiosarcomatous carcinoma components such as conventional urothelial carcinoma (5), squamous differentiation (4), sarcomatoid spindle cell carcinoma (2), small cell carcinoma (1), micropapillary carcinoma (1), and glandular differentiation (1). The pseudoangiosarcomatous urothelial carcinomas were all (7/7) diffusely CK7 positive, most (6/7) were GATA3 positive, and none (0/7) expressed vascular-associated markers. There was no evidence to suggest that apoptosis (by TUNEL assay and cleaved caspase-3 immunostaining) or loss of the adhesion molecules CD138 and e-cadherin were possible causes for the tumor cell discohesion and breakdown. All 7 tumors were high stage at cystectomy and included 1 pT3a, 2 pT3b, and 4 pT4a tumors, and 3 had pelvic lymph node involvement. Follow-up data available in 6 cases revealed a poor outcome with an overall median survival of 8.5 months. In conclusion, we present an unusual morphology of bladder carcinoma that has a striking resemblance to a malignant vasoformative tumor. Our series showed that bladder pseudoangiosarcomatous carcinoma morphology is associated with a higher tumor stage at cystectomy, commonly admixed with other aggressive carcinoma variant morphologies, and portend a poorer outcome. Knowledge of this pattern is also important to avoid misdiagnosis, particularly in limited tissue samples.

Anastomosing hemangioma, a benign vascular neoplasm histologically simulating angiosarcoma, is newly recognized and has been described primarily in the genitourinary tract. We have encountered this lesion in the liver and gastrointestinal tract, where it can be diagnostically challenging, especially in core biopsy. Herein, we described 6 cases of anastomosing hemangioma of the liver and gastrointestinal tract. They occurred in 4 women and 2 men, ranging in age from 48 to 71 years. The tumors ranged from 0.2 to 6 cm (median, 3.1 cm) and were grossly well demarcated with a gray-brown spongy appearance. Microscopically, they had a loosely lobulated architecture. At higher magnification, lesions consisted of anastomosing sinusoidal capillary-sized vessels with scattered hobnail endothelial cells. Mild cytologic atypia occurred in all cases. Mitoses were absent. Vascular thrombi were seen in 4 cases (66.7%) without necrosis. One tumor (16.7%) featured prominent extramedullary hematopoiesis and 1 (16.7%) hyaline globules. Immunohistochemistry results were available for 3 cases, and the lesions stained with CD34 and/or CD31. Five cases had clinical follow-up information; there were no recurrences or metastases (range, 8 to 96 mo; mean, 41 mo), and 1 patient received no follow-up after a benign diagnosis on her colon polyp. In summary, anastomosing hemangioma of the liver and gastrointestinal tract is a rare distinctive vascular neoplasm displaying overlapping features with well-differentiated angiosarcoma. Despite small numbers and limited follow-up information in our series, evidence to date supports that the lesion is benign. Awareness of this entity is essential to avoid overdiagnosis and unnecessary aggressive treatment.

Prox1, a transcription factor important in the regulation and maintenance of the lymphatic endothelial phenotype, is consistently expressed in lymphangiomas and Kaposi sarcoma and has also been reported in Kaposiform hemangioendothelioma. However, information on its distribution in vascular tumors, such as angiosarcoma, is limited. In this study, we examined selected normal tissues and 314 vascular endothelial and 1086 nonvascular tumors to get an insight into the biology of these tumors and on potential diagnostic use of Prox1 as an immunohistochemical marker. In adult tissues, Prox1 was essentially restricted to lymphatic endothelia, with expression in subsets of pancreatic and gastrointestinal epithelia. However, it was also detected in embryonic liver and heart. Prox1 was consistently expressed in lymphangiomas, venous hemangiomas, Kaposi sarcoma, in endothelia of spindle cell hemangioma, Kaposiform hemangioendothelioma, and retiform hemangioendothelioma, and in half of epithelioid hemangioendotheliomas. It was present in most cutaneous angiosarcomas from different sites but was less commonly expressed in deep soft tissue and visceral angiosarcomas. In contrast, Prox1 was generally absent in capillary and cavernous hemangiomas. In positive hemangiomas and angiosarcomas it was coexpressed with podoplanin, another marker of the lymphatic endothelial phenotype. There was an inverse correlation with CD34 expression. The expression in mesenchymal nonendothelial neoplasm was limited. Prox1 was detected in 5 of 27 synovial sarcomas, specifically in the epithelia of biphasic tumors. Four of 16 Ewing sarcomas and 5 of 15 paragangliomas were also positive. All melanomas and undifferentiated sarcomas were negative. Among epithelial neoplasms, Prox1 was detected in 18 of 38 colonic carcinomas and 10 of 15 cholangiocarcinomas and in a minority of pulmonary, prostatic, and endometrial adenocarcinomas. The common Prox1 expression in angiosarcoma and its rare presence in nonvascular mesenchymal tumors make this marker suitable for the diagnosis of angiosarcoma and Kaposi sarcoma. However, the presence of Prox1 in some malignant epithelial tumors necessitates caution in applying Prox1 as a marker for vascular tumors. Common Prox1 expression in angiosarcoma may reflect the lymphatic endothelial phenotype in these tumors. Its patterns of expression in hemangiomas and angiosarcoma may be diagnostically useful and offer a new parameter in the biological classification of vascular tumors.

Epithelioid angiosarcomas are rare aggressive neoplasms that occur most frequently in deep soft tissues. Primary cutaneous lesions are rare, and there are discrepant findings in the literature regarding their behavior. In this study, we report a series of 13 cases of primary cutaneous epithelioid angiosarcoma and analyze their clinicopathologic features. The tumors arising in the conventional settings for cutaneous angiosarcoma (ie, in the head and neck region of elderly patients, and those occurring postradiation or associated with lymphedema) were excluded. Primary cutaneous epithelioid angiosarcoma occurred in adults (mean age, 66 y) with an equal sex distribution, and presented as solitary (n=10) or multiple (n=3) nodules ranging in size from 8 to 80 mm, with a predilection for the limbs (n=10). Histopathologically, the tumors comprised infiltrative sheets of atypical epithelioid cells within the dermis with or without the involvement of the subcutis. Vascular channel formation and intracytoplasmic lumina were seen, at least focally, in most cases. Mitoses were readily identified and necrosis was seen in 40% of the cases. The tumors were immunoreactive for vascular markers, with CD31 and FLI-1 offering the highest sensitivity. Pancytokeratin was positive in two thirds of the cases, and epithelial membrane antigen was positive in one-quarter of the cases. There was rare focal expression of Melan-A (n=2) and smooth muscle actin (n=3). Follow-up information was available for 11 patients. Six patients died of metastatic disease after a median follow-up of 12 months (range, 3 to 36 mo), and 1 patient died of unrelated causes. These findings suggest that primary cutaneous epithelioid angiosarcoma occurring outside the conventional settings of angiosarcoma is a highly aggressive malignant tumor with mortality rates in excess of 55% after 3 years.

Cutaneous angiosarcomas are rare tumors, which predominantly arise in the sun-exposed skin of the head and neck of adult and elderly patients. Rarely, these tumors can be seen in children. We identified cutaneous angiosarcomas in 10 children and assessed clinical (patient age, tumor site, tumor size, and tumor focality) and histologic features including growth pattern (vasoformative vs. solid), mitotic rate (mitotic figures per 10 high power field), necrosis (present vs. absent), and cell shape (epithelioid vs. nonepithelioid). Tumors predominated in the lower extremities (6 of 10) of female patients (2 male and 8 female); age at diagnosis ranged from 1.5 months to 15 years. Four patients had preexisting conditions: congenital hemihypertrophy of the contralateral limb, the Aicardi syndrome, congenital lymphedema, and congenital hemangioma treated with radiation therapy. Tumors were located in the lower extremity (6), flank (1), elbow (1), and buccal mucosa (1), and ranged in size from 0.6 to 6.5 cm. Eight cases showed predominantly epithelioid morphology, 1 case showed mixed epithelioid and spindled morphology and 1 case was entirely spindled. Mitotic activity ranged from 1 to 55 mitotic figures per 10 high power field. Necrosis was seen in 5 cases. Clinical follow-up was obtained for 9 patients: 4 died of disease (range, 12 to 49 mo; mean, 25 mo) and 5 patients were alive without disease (18 mo to 28 y). Five patients had metastatic disease; sites of involvement included the lung, soft tissue, lymph node, pleura, liver, and bone. Cutaneous angiosarcomas in children are rare tumors, which are commonly associated with a preexisting condition, suggesting a greater role for genetics as opposed to environmental factors in the pathogenesis of these tumors.

We report 18 cases of cutaneous angiosarcoma with predominant or exclusive epithelioid morphology. Both sexes were similarly affected. Patients' ages ranged from 2 to 97 years, median 77.5 years; 2 were pediatric patients. In elderly patients scalp or facial lesions and cutaneous lesions arising within irradiated breast skin predominated. Limb lesions were seen in younger patients. Microscopically, the tumors were composed of packed polygonal cells with focal evidence of endothelial differentiation. Diverging phenotypes included syncytial growth of large cells with clear nuclei and prominent nucleoli, micronodules of tumor cells scattered in dermis, predominance of discohesive plasmacytoid polygonal cells with abundant bright eosinophilic cytoplasm, sheets of clear cells with coarse granular cytoplasm, trabecular and cord arrangement of tumor cells splaying the dermal collagen, or a pseudoglandular appearance owing to clear cell tubular arrangement with open lumina. These cases posed further diagnostic challenges simulating lymphoma, melanoma, lymphoepithelioma-like carcinoma, adnexal carcinoma, and neuroendocrine carcinoma. Immunohistochemical studies showed positivity for CD31 and CD34; no immunoreactivity was documented for other tested antigens including cytokeratins, S100 protein, melanocytic antigens, leukocyte common antigen, and desmin. Therapeutic modalities included combined local excision, chemotherapy, and radiotherapy, depending on patient clinical status. Of the 9 patients available for follow-up, 5 were alive and apparently well, 2 had recurrent disease, and 2 had died of tumor. Our data show that epithelioid cutaneous angiosarcoma may have a broad morphological spectrum, raising interpretive challenges on microscopy. In addition, its clinical presentation seems to differ in nonelderly patients, with lesions likely related to lymphedema or vascular malformations.

Vascular tumors of the kidney are distinctly rare, and to date no large series have been reported. We analyzed a series of primary vascular tumors of the kidney to further delineate their clinicopathologic features and identify organ-specific morphologic features, if present. Twenty-five renal cases previously coded as "arteriovenous malformation," "hemangioma," and "angiosarcoma" were retrieved from the archives of 4 collaborating institutions and were reevaluated histologically. Tumors were classified according to the 2002 World Health Organization classification of tumors of soft tissue and bone. There were 18 males and 7 females (M:F=2.6:1) ranging from 21 to 95 years (mean 56.7 y). Lesions ranged from "microscopic" to 30 cm (mean 6.0 cm) and were tan-brown, cystic, and hemorrhagic. On re-review, cases were classified as arteriovenous malformation (n=3), capillary hemangioma (n=14), and angiosarcoma (n=8). Arteriovenous malformations were identical to their somatic soft tissue counterparts. Renal capillary hemangiomas often lacked a well-formed lobular pattern and 5 cases showed a "sieve-like" arrangement reminiscent of splenic sinusoids, a pattern previously noted by others (anastomosing hemangioma). All hemangiomas were noninfiltrative and lacked cytologic atypia and mitotic activity. GLUT-1, D2-40, and CD8 were performed in 3 anastomosing hemangiomas and were all negative. Angiosarcomas were diffusely infiltrative with extensive parenchymal destruction; all showed at least small areas of conventional vasoformative growth, but were frequently dominated by spindled and epithelioid histology. All cases were positive for some combination of vascular tumor-associated markers (CD31, CD34, and FLI-1). Cytokeratin expression was absent in all angiosarcomas. Follow-up was available for 15 cases: all patients with arteriovenous malformation and hemangioma with follow-up were disease free after complete excision; 4 cases of angiosarcoma died of the disease at 1, 1, 6, and 11 months. Our review shows that many capillary hemangiomas of the kidney are morphologically distinctive tumors, which often show "spleen-like" or "anastomosing" features. Angiosarcomas of the kidney are highly aggressive tumors with poor outcome and may have morphologic features (spindling and epithelioid change), which could result in confusion with sarcomatoid carcinomas and other renal mesenchymal tumors.

Background: We describe 6 cases of a poorly recognized vascular neoplasm that can simulate angiosarcoma., Design: Cases of a rare vascular tumor with a proclivity for the genitourinary tract encountered in our consultation material were prospectively collected between the year 1999 and 2008. Follow-up information was obtained when possible., Results: There were 6 tumors from 4 men (66%) and 2 women, ranging in age from 49 to 75 years (median, 59.5) involving the kidney and renal hilum (4, 66%) and testis (2). Tumors ranged from 1.3 to 1.7 cm (median, 1.6 cm) and were grossly well-marginated with a hemorrhagic mahogany spongy appearance. Microscopically, at low power they had a loosely lobulated architecture and were associated with a medium-caliber vessel (5/6, 83%). Most kidney (3/4, 75%) tumors showed minor extensions into adjacent adipose tissue. At higher magnification, the tumors consisted of anastomosing sinusoidal capillary-sized vessels with scattered hobnail endothelial cells within a framework of nonendothelial supporting cells. There was a minimal inflammatory backdrop consisting of lymphocytes but not plasma cells or acute inflammation. Mitoses were absent (5/6, 83%) or rare (1 case; in supporting cells). There was mild cytologic atypia in one of the cases but no multilayering of endothelial cells in any case. Vascular thrombi were typical (5/6, 83%) and the lesions had zones of central sclerosis with focal necrosis (5/6, 83%). Two (33%) tumors featured prominent extra-medullary hematopoiesis and 2 tumors (33%) had striking hyaline globules reminiscent of those seen in Kaposi's sarcoma. Immunohistochemistry was available on some cases and the lesions stained with CD34, CD31, and FVIII but not human herpes virus type 8, keratin AE1/3, epithelial membrane antigen, HMB45, placental alkaline phosphatase, or human chorionic gonadotropin. In all but one submitted consultation, the possibility of angiosarcoma had been raised based on the anastomosing vascular pattern. On follow-up, there were no recurrences or metastases in 5 cases (range: 8 to 36 mo; median 12 mo, mean 15 mo), and 1 patient was lost to follow-up., Conclusions: Anastomosing hemangioma of the genitourinary tract is a rare neoplasm displaying some overlapping features of both sinusoidal hemangioma and hobnail hemangioma of soft tissue and skin. However, in our opinion, it is a unique neoplasm with a proclivity for the kidney. Its anastomosing appearance can lead to concern for angiosarcoma but, despite small numbers and limited follow-up in our series, evidence to date supports that the lesion is benign.

Angiosarcomas are rare tumors that predominantly affect adult and elderly patients and pursue an aggressive clinical course with high mortality. Although angiosarcomas are well described in a variety of clinical settings, they have been incompletely characterized. We identified 15 high-grade angiosarcomas arising from the viscera and soft tissue of patients 21 years old and younger from institutional and consultation files. Both clinical (patient age, tumor site, tumor size, tumor focality) and histologic features including growth pattern (vasoformative vs. solid), nuclear grade (high vs. low), mitotic rate (mitotic figures/10 high-power fields), necrosis (present vs. absent), and cell shape (epithelioid vs. nonepithelioid) were assessed. Tumors arose in both sexes (8 males; 7 females); age at diagnosis ranged from 3 months to 19 years (mean, 10 y, 5 mo; median, 11 y). Tumors were located in the mediastinum (7), visceral organs (2 in liver, 1 in spleen), breast (2), mesentery (1), pelvis (1), and deep soft tissue of upper extremity (1). Tumor size was documented for 8 patients (range 3.5 to 13 cm; mean 8.1 cm). Eight cases showed epithelioid morphology and 7 cases were primarily spindled. Of 8 cases assessed for podoplanin expression by immunohistochemistry, 7 were negative and 1 was positive. Clinical follow-up was obtained for all patients: 10 (67%) died of disease (range, 27 mo to 11 y; mean, 6 y 8 mo) and 4 patients were alive without disease (range, 27 to 132 mo; mean, 79 mo). Although extremely rare, angiosarcomas do affect children and young adults and this diagnosis should be considered in atypical vascular tumors occurring in the mediastinum and those with brisk mitotic activity and/or necrosis.

Mammary angiosarcoma is a rare neoplasm, accounting for about 0.05% of all primary malignancies of the breast. It is currently believed that histologic grading of mammary angiosarcomas plays an important role in prognostication. Forty-nine cases of primary angiosarcoma of the breast were retrieved from our files. Clinical details and follow-up information were obtained from referring pathologists and clinicians, and by chart review. All statistics were performed using Fisher exact test and only P<0.05 was considered significant. Recurrence-free survival and overall survival curves were established using Statistica software version 5.5 (StatSoft Inc). All patients were female with ages ranging from 15 to 74 years (mean 41.5, median 40). Peak incidence was between the ages of 30 and 50 years. All tumors examined were located within breast parenchyma with or without minor cutaneous involvement. The right side was more commonly affected than the left side (66% vs. 29.5%). Tumor was bilateral at presentation in 2 cases (4.5%). Tumor size varied from 0.7 to 25 cm (mean 6.7, median 5). Most patients presented with a palpable, painless mass. Two patients had a history of prior radiation treatment for breast carcinoma. Histologically, primary tumors were graded using Rosen's 3-tier system: 17 tumors (35.4%) as low grade, 17 (35.4%) as intermediate grade, and 14 (29.2%) as high grade. Forty-six patients were treated surgically, 11 underwent chemotherapy, and 12 patients received radiotherapy. Follow-up was available in 41 patients (83.7%, median duration 29 mo). Ten patients (24.4%) showed evidence of local recurrence within 11 to 60 months (median 36) after diagnosis. Twenty-four patients (58.5%) thus far have developed metastases, which were most commonly to lung, liver, skin, and bone. Time interval between diagnosis and metastasis ranged from 2 to 144 months (median 34). Eighteen patients (44%) so far have died of disease and 1 died of presumably disseminated breast carcinoma. Five patients (12.2%) are alive with disease and 15 patients (36.6%) are alive with no evidence of disease. Statistical analysis evaluating correlation between tumor grade and size, and rate of local recurrence, metastasis, and death owing to disease showed no significant difference among tumors of different grades. The median recurrence-free and overall survival rates for the entire cohort were 2.8 and 5.7 years, respectively. In conclusion, mammary angiosarcoma is a rare disease that affects relatively younger patients. This tumor seems to have an overall similar clinical course as other types of angiosarcoma arising in skin or soft tissue; it carries a moderate risk of local recurrence, and a high risk of metastasis and death. In this large series, there is no correlation between histologic grade and patient outcome, more in line with angiosarcomas at other sites.

Vascular tumors of the bladder are rare and a subject of small series and case reports. We retrospectively identified vascular tumors of the urinary bladder from the consultation files from one of the authors. We identified 13 lesions that included 3 hemangiomas, 3 intravascular papillary endothelial hyperplasias (Masson vegetant hemangioendotheliomas), 2 arteriovenous malformations (AVMs), 1 epithelioid hemangioendothelioma (EHE), and 4 angiosarcomas. One of the angiosarcomas was associated with conventional high-grade urothelial carcinoma (sarcomatoid carcinoma). All patients were adults with a range in age from 18 to 85 years old (mean 63.3). There was no statistical difference among the various lesions in terms of age, although angiosarcomas tended to arise in older patients (mean 71 y vs. 60 y of the remainder). Hematuria was the most common presentation of both benign and malignant lesions. Other symptoms included voiding irritation, pelvic pain, and obstruction. Histologically, benign and malignant lesions were similar to their counterparts in other organ systems. Two hemangiomas were of the capillary type and a third one of the cavernous subtype. They measured 1.1, 2.4, and 3.2 cm. Both AVMs were clinically large broad-based masses measuring 5.5 and 5.8 cm in greatest diameter. One of the AVMs was associated with pseudoepitheliomatous hyperplasia of the urothelium. All 3 patients with Masson lesion had history of radiation therapy for other causes. These presented as raised lesions and were all <1.0 cm. Patients with hemangiomas, papillary endothelial hyperplasias, and AVM had an invariably benign prognosis and needed no further therapy. These benign lesions had consistent involvement of the submucosa and spared the muscularis propria of the organ. All cases of angiosarcoma and EHE involved the muscularis propria. Two of four patients with angiosarcoma had a history of prior radiation therapy and all 4 were dead of disease at 6 months. Angiosarcomas measured 3, 4.5, 5, and 5.8 cm in greatest diameter at cystoscopy. The patient with EHE had a single nodule treated by transurethral resection of the bladder and no evidence of disease at 4 years of follow-up. None of the patients experienced marked gross hematuria that resulted in morbidity or mortality. A wide spectrum of benign, intermediate malignant, and malignant vascular lesions primarily involved the bladder. Despite the potential for marked hemorrhage, none of the tumors resulted in marked hematuria. Papillary endothelial hyperplasia occurs in the bladder and must be differentiated from angiosarcoma, which has a rapidly fatal outcome.

We report the clinicopathologic study of 32 cases of atypical vascular lesions (AVLs) after surgery and radiation of the breast, which were referred to us in consultation over a 17-year period. The patients, all women, ranged in age from 41 to 95 years (mean 61 y). The lesions developed within the radiation field from 1 to 12 years (median 6.0 y) after therapy. They occurred as one (n=18) or more (n=10) flesh-colored papules or erythematous patches/plaques ranging in size from 1 to 60 mm (mean 8.0 mm, median 4.0 mm). Tumors could be divided into 2 histologic types: a lymphatic type (LT) (n=22) and a vascular type (VT) (n=10). LT AVLs consisted predominantly of thin-walled, variably anastomosing lymphatic vessels that were usually confined to the superficial dermis but occasionally extended into the deep dermis and even subcutis. The VT (n=10) typically consisted of small, irregularly dispersed, often blood-filled, pericyte-invested, capillary-sized vessels involving the superficial or deep dermis. VTs were often associated with extravasated erythrocytes, hemosiderin, and a surrounding minor LT component. In 4 cases, endothelial atypia, consisting of nuclear and nucleolar enlargement, was noted. Follow-up of 21 patients with LT AVLs (1 to 106 mo; mean 47 mo) disclosed recurrence/additional lesions in 6, all of whom had additional surgery. Of the 21 patients, 17 are alive without disease, 1 is alive with disease, 1 died of breast carcinoma, 1 died of unknown causes, and 1 showed progressive histologic changes in the AVLs over a period of 5 years resulting in a well-differentiated angiosarcoma. Follow-up in 8 patients with VT AVL (2 to 181 mo; mean 40 mo) disclosed that 6 were alive and well, but 2 of the 4 patients whose lesions displayed endothelial atypia had additional complications. One patient underwent a mastectomy that revealed extensive residual AVL and the second developed a high-grade angiosarcoma after 14 months. We conclude that AVLs encompass a wider spectrum of changes than previously appreciated, ranging from superficial lymphatic proliferations to more complex lymphatic and capillary vascular lesions. There seems to be an association of AVL with angiosarcoma that differs depending on the histologic features, with the VT AVLs having the higher risk. In the 2 patients who developed angiosarcoma, morphologic evidence suggested AVLs to be a precursor rather than simply a risk factor. Future outcome and management studies should take into account these differences.

Angiosarcomas have traditionally been considered high-grade lesions for which histologic features and grading have played no role in prognostication and, consequently, they have been excluded from the American Joint Committee on Cancer staging system. We have, therefore, analyzed 69 cutaneous angiosarcomas seen in consultation and not associated with lymphedema or prior radiation therapy to determine if a combination of histologic and clinical parameters could be used to differentiate indolent from aggressive tumors. The clinical features analyzed included patient age, location, size, depth, and focality of the lesion; the histologic features studied included pattern of growth (vasoformative vs. solid), nuclear grade (high vs. low), necrosis (present/absent), cell type (epithelioid or spindled), extent of inflammatory infiltrate (minimal vs. marked), and mitotic rate. Lesions occurred on the head/neck (49), extremities (15), and trunk (5) of adults (21 to 94 y) and predominated in males (41 males; 28 females). Tumors ranged in size from 0.3 to 15 cm (average 3.1 cm) and involved the papillary (n=9), reticular (n=16), or deep dermis/ subcutis (n=30). They could be predominantly vasoformative (n=28) to solid (greater than 50% solid, n=41). Most lesions were of high (n=65) as opposed to low (n=4) nuclear grade, were mitotically active (0 to 99/10 high power fields), and occasionally displayed necrosis (n=14) and epithelioid features (n=21). Inflammatory infiltrates were minimal in most cases. Follow-up information was obtained for all patients. Recurrences developed in 18 patients (26%) and metastasis in 15 (22%) to the following sites: lung (6), lymph node (7), liver (2), bone (2), and parotid gland (1). Forty-seven patients died (30 of disease) and 22 were alive at last known follow-up (range, 16 to 158 mo; mean, 65; median, 36). Five-year disease-specific survival was 48%. By univariate analysis only older age, anatomic site, necrosis, and epithelioid features correlated with increased mortality. Tumors were stratified into low (n=41) or high (n=28) risk groups based on necrosis and/or epithelioid features. By multivariable analysis, high-risk group (hazard ratio 4.07, P=0.0004) and age >70 (hazard ratio 2.79, P=0.012) were associated with increased mortality, and tumor depth (P=0.048) correlated with the risk of local recurrence. The high-risk group had a significantly worse prognosis than the low-risk group with 3-year survival of 24% and 77%, respectively. No patients with high-risk features survived 5 years. In conclusion, we report that a combination of clinical and histologic features allows stratification of angiosarcoma patients into 2 risk groups that are strongly associated with marked differences in clinical course. These features seem to diminish in importance with increased tumor size and are probably most useful in tumors less than 5 cm in maximum dimension.

Cutaneous angiosarcoma is a rare but well-recognized complication after radiation therapy. Atypical post-radiation vascular lesions (AVLs) with a benign course have been described recently, but few cases with limited follow-up have been studied so far. A total of 42 cases diagnosed as either radiation-associated cutaneous vascular lesions or angiosarcoma were retrieved from departmental and consultation files from 1995 to 2003. Hematoxylin and eosin-stained sections and clinical as well as follow-up data were evaluated. All patients were female with a median age of 59 years (range, 36-90 years). Presentation ranged from small erythematous/violaceous papules or nodules to large plaques with discoloration located on the chest wall (35), abdomen (2), shoulder, groin, flank, axilla, and lower leg (1 each). Reasons for radiation included breast carcinoma (35 cases) and a variety of other lesions (mainly malignant disease). Size range was 0.1 to 20 cm. Angiosarcomas presented as larger lesions (median, 7.5 cm) compared with AVLs (median, 0.5 cm). The time interval from radiation was significantly shorter for the development of AVL (median, 3.5 years) compared with cutaneous angiosarcoma (median, 6 years). Histologic evaluation revealed 26 lesions meeting criteria for angiosarcoma, ranging from morphologically low-grade to high-grade; 16 cases were classified as AVLs. These were fairly well-circumscribed lesions confined within superficial to mid dermis and composed of complex anastomosing and focally dilated vascular spaces. Some showed prominent hyperchromatic endothelial cells, while others were characterized by areas with a dissecting growth pattern within dermal collagen. Endothelial multilayering was absent. Clinical follow-up, available for 36 patients (range, 2-84 months; median, 17 months), revealed 4 patients who died of disease, 4 patients had systemic metastasis, and 12 patients with local recurrence. All patients with systemic relapse had an initial diagnosis of angiosarcoma. One patient with an AVL had a recurrence at the same site, 3 patients developed additional new lesions, and 1 patient developed multiple small papules on the chest wall, which progressed from an AVL to angiosarcoma. This study outlines the morphologic spectrum of radiation-associated cutaneous AVLs. No adverse outcome has been observed so far in this more benign subset of cases, but longer-term follow-up is necessary.

Iatrogenic angiosarcomas (AS), following treatment of breast carcinomas and attributed to chronic lymphedema, were first described by Stewart and Treves. With emphasis on breast-conserving therapy combined with adjuvant radiation, a recently recognized form of cutaneous postradiation angiosarcoma of the breast (CPRASB) has emerged. To more completely characterize CPRASB, 27 cases were analyzed. Histologic features studied included pattern of growth (vasoformative, sieve-like, or solid), nuclear grade, necrosis, and mitotic rate. Clinical and follow-up information was obtained. The patients received relatively standard radiation treatment. The median interval to diagnosis of CPRASB was 59 months; 5 occurred in less than 3 years. Lymphedema was largely absent, and when present was only mild in nature. CPRASB was frequently multifocal at presentation (13 of 27). All tumors had a vasoformative pattern of growth; the majority (16 of 27) had areas with a sieve-like pattern. The solid pattern was less frequent (7 of 27). The majority had high-grade nuclear features (16 grade 3, 8 grade 2, 3 grade1). The mean mitotic rate was 9/10 HPF. Necrosis was rare (2 of 27). All were treated with wide excision or mastectomy. Follow-up was available on 22 of 27 cases (median 44 months). Fourteen experienced local recurrence and 6 had multiple recurrences. Metastasis was documented in 9 of 22 patients and involved lungs (6), contralateral breast (3), skeleton (2), lymph nodes (1), and soft tissue (1). Eight patients died of disease, 2 died with disease, 4 were alive with disease, and 8 are alive without disease. The median interval to death was 33.5 months. All 4 patients with disease have documented metastasis. CPRASB differs from Stewart-Treves AS by its shorter latency period and lack of association with lymphedema.

Epithelioid hemangiomas of the penis are very rare. To date, less than 10 examples have been reported in the English language literature. In this report, we describe the clinical, histopathologic, and immunohistochemical findings in 19 cases retrieved from our files. The patients ranged in age from 23 to 75 years (median age, 45 years) at the time of initial surgical resection. Seventeen patients presented with a solitary mass, and two presented with two separate, but closely approximated, lesions. The process involved the glans penis (n = 3), shaft (n = 11), base of the penis (n = 2), or penis, not otherwise specified (n = 3). The lesions ranged in size from <0.5 to 2.5 cm (median size, approximately 1.2 cm) in greatest dimension. Eleven examples were specifically noted to be dorsally located, and only one was stated to be ventral. Localized pain or tenderness was the most common complaint, documented in 12 cases. The preoperative duration of the lesions ranged from 5 days to 1 year (median 4.5 months). Microscopically, all examples contained a tumefactive proliferation of epithelioid endothelial cells, often in a nodular or lobular configuration and associated with an inflammatory infiltrate containing lymphocytes and eosinophils. In 14 cases, the vascular proliferation was associated with a small arterial segment, sometimes with mural damage and frequently (n = 13) with intraluminal epithelioid endothelial cells. Based on the growth pattern of the epithelioid endothelial cells, 13 cases were considered "typical," and six were considered exuberant or "atypical." The latter examples had a prominent centrally located zone where nests or sheet-like aggregates of epithelioid endothelial cells did not form discrete vessels. Immunohistochemical data are available for 15 tumors. The epithelioid endothelial cells usually had strong reactivity for CD31, lesser reactivity for factor VIIIrAg, and minimal reactivity for CD34. In 9 of 12 cases, a small number of epithelioid endothelial cells expressed keratins. In all cases tested, at least focal muscle-specific actin-positive myopericytic cells were present bordering the endothelial cells, and this was especially notable peripherally. Initial surgical intervention consisted of either a shave biopsy (n = 1), excisional biopsy (n = 2), or local excision (n = 16). A complete follow-up history is available for 12 patients, and incomplete follow-up information is available for an additional four patients. One patient developed a new epithelioid hemangioma at a site within the penis separate from the initial lesion, but no patient is known to have experienced a true metastasis or to have died of complications of this process. Optimal management appears to be complete local excision with periodic follow-up visits to monitor for local recurrence.

The clinical and pathologic features of 10 epithelioid angiosarcomas of bone were analyzed. There were eight males and two females who ranged in age from 26 to 83 years (mean 62 years). Four tumors were solitary and six were multifocal. In two consultation cases, the submitted diagnosis was metastatic carcinoma. Microscopically, the tumor cells were arranged in solid and infiltrative sheets, and in most cases vascular channels or cystically dilated spaces were present. The neoplastic cells had abundant eosinophilic cytoplasm and large nuclei with open chromatin and prominent eosinophilic nucleoli. Intratumoral hemorrhage, neutrophilic infiltrates, and intracytoplasmic lumina were frequently present. All 10 tumors stained positive for one or more endothelial markers, with CD31 being the most sensitive marker. Seven cases stained positive for cytokeratin. Ultrastructural examination in three tumors confirmed their endothelial differentiation. In the absence of obvious vascular differentiation, abundant intratumoral hemorrhage and intratumoral neutrophils are useful ancillary morphologic features that may suggest a vascular origin. Six patients are dead of disease, one is alive with metastasis, and two patients are currently disease free. Epithelioid angiosarcoma of bone should be included in the differential diagnosis of epithelioid neoplasms of bone, and endothelial markers should be a part of their immunohistochemical analysis to avoid the misdiagnosis of a metastatic carcinoma because of the significant differences in the treatment and clinical outcomes of these entities.

We are reporting seven histologically identical cases of a distinctive, low-grade vascular tumor that closely mimics an epithelioid sarcoma because of growth in solid sheets and nests, the eosinophilia of the rounded to slightly spindled neoplastic cells, and the diffuse, strong cytokeratin expression. Termed epithelioid sarcoma-like hemangioendothelioma, all were diagnosed by the submitting pathologist or another expert consultant as epithelioid sarcoma. Although none displayed architectural evidence of vascular differentiation in the form of multicellular vascular channels, some displayed subtle cytologic features of vascular differentiation and all displayed immunohistochemical evidence of endothelial differentiation. The patients (four male; three female) ranged in age from 17 to 54 years (median 23 years). Ranging in size from 1 to 3.5 cm, they occurred in the extremities (n = 5), scalp (n = 1), and chest wall (n = 1), both in deep (n = 3) and superficial (n = 3) soft tissue or both (n = 1). The tumors were characterized by sheets, ill-defined nodules, or fascicles of deeply eosinophilic cells set within a desmoplastic stroma. Multicellular vascular channel formation and/or hemorrhage were absent in all cases. In four cases intracytoplasmic vacuolization suggestive of intracytoplasmic vascular lumen formation was noted. The typical neoplastic cell was large and rounded in shape but modulated in areas to a spindled or multipolar shape. Mitotic activity was low (<5 mitotic figures/50 high power fields), nuclear pleomorphism was mild to moderate, and necrosis was absent. The tumors were positive for cytokeratin (6 of 6), vimentin (6 of 6), CD31 (5 of 6), FLI-1 (6 of 6), but negative for CD34 (0 of 6). Within a follow-up period of 3-72 months (median 39 months), two patients experienced a local recurrence and one patient regional soft tissue metastases, but no distant ones. Two patients presented with multifocal lesions suggestive of regional metastases. Currently, two patients are alive with disease and five are disease free. Epithelioid sarcoma-like hemangioendothelioma appears to be a largely unrecognized epithelioid vascular tumor with an indolent course. Despite its similar clinical and histologic features, it differs from epithelioid sarcoma by the presence of endothelial markers and the absence to date of distant metastases. Its distinction from other epithelioid vascular lesions is discussed. We think this tumor fits best into the family of "hemangioendothelioma" or vascular lesions of intermediate malignancy.

FKBP12 is a cytosolic FK506 binding protein that interacts with calcineurin and thereby mediates the immunosuppressive effects of FK506. Because initial immunohistochemical staining showed abundant expression of FKBP12 in vascular endothelial cells, we evaluated whether it could serve as a marker for vascular neoplasms. We performed immunohistochemical staining of conventional sections from formalin-fixed, paraffin-embedded tissue from 59 benign and malignant vascular neoplasms using a polyclonal rabbit antiserum against FKBP12. Western blot analysis of tissue from 6 angiosarcomas showed a single band at 12 kD, consistent with the published molecular weight for the FKBP12 protein. Together, CD31, CD34, and FKBP12 identified all 59 vascular neoplasms in this study. Specificity of immunohistochemical staining was assessed on 1,321 tissues represented on 7 tissue microarrays. All proteins were occasionally expressed in non-vascular tissue. Six of 8 vascular neoplasms represented on the arrays stained for FKBP12, as did normal vessels in numerous cores. The polyclonal antiserum shows comparable sensitivity (94.9%) and specificity (96.5%) to CD34 and CD31 and may be a useful additional marker for vascular differentiation. Because we have evaluated a large number of tissues by tissue microarray, we anticipate that our estimate of the specificity of immunostaining for FKBP12 as a marker for vascular endothelium will be accurate. In addition, our findings may explain the toxic effects of FK506 on vascular endothelium of the kidney.

Malignant change in a benign vascular tumor is exceedingly rare, and there have been only five previously reported convincing cases. Four new cases of angiosarcoma (AS) arising in a hemangioma/vascular malformation (HVM) are described. All patients were in the 6th or 7th decade of life (two female, two male). Development of an enlarging deep-seated mass was the main presenting symptom. MRI disclosed the presence of two separate soft tissue masses in both thighs in one patient. No patient had a history of prior radiotherapy at the same site. Preoperative duration, known in three cases, ranged from 1 to 24 months (median 12 months). Three tumors were located in the lower extremities (thigh and buttock), one in the retroperitoneum, and one in the parotid region. Three patients were treated by marginal excision; in one case only a biopsy was performed. Radiotherapy/chemotherapy was given in all cases. Two patients were disease free 2 and 14 months after surgery and two developed metastases. Grossly, the tumors were described as frankly hemorrhagic masses or as firm, whitish areas with hemorrhagic nodules and were centered in skeletal muscle in three cases. Size ranged between 2.2 cm and 8 cm (median 4.3 cm). Histologically, all the tumors had two distinct components. In three cases the benign and the malignant components were variably intermixed, whereas in one case the HVM was mainly located at the edge of the malignant tumor. The benign component showed features of an arteriovenous hemangioma (three cases) or intramuscular capillary hemangioma. AS showed epithelioid morphology in three cases and a well-differentiated dissecting pattern in one case. An imperceptible transition between the two components was noted in two cases. The two anatomically separate masses excised from one patient appeared almost identical. All cases were positive for at least two endothelial markers (CD31, CD34, VWF) and negative for the epithelial markers (EMA, AE1/AE3, Pan-keratin). Possible mechanisms for this exceptional phenomenon are discussed.

Rhabdomyosarcomas (RMSs) are classified into embryonal (ERMS), alveolar (ARMS), and pleomorphic (PRMS) subtypes. ERMS, including botryoid variants, typically occurs in young children, ARMS typically occurs in older children and young adults, and PRMS occurs in older adults. Although ARMSs show thin fibrous bands separating nests of cells, abundant extracellular matrix production is rare in RMS. In the course of reviewing hyalinizing sarcomas we discovered a distinctive RMS in adults that closely mimicked osteosarcoma or chondrosarcoma because of the extensive matrix production. Four RMSs with hyalinized matrix were retrieved from our files. These cases were evaluated with respect to patient age and sex, tumor site and size, growth pattern, nuclear grade, cellularity, mitotic figures/20 high power fields, vascular invasion, necrosis, the presence of rhabdomyoblasts, multinucleated cells, and alveolar growth pattern. Immunohistochemistry for desmin, myogenin, MyoD1, actin, cytokeratin, S-100 protein, collagen II, and CD99 was performed. Reverse transcriptase polymerase chain reaction for the ARMS-associated PAX3/FKHR and PAX7/PKHF was also performed on three cases. The cases involved the forearm, hand, orbit, and nasopharynx of a 40-year-old woman, a 50-year-old man, an 18-year-old man, and a 21-year-old man, respectively. The tumors ranged from 3.7 to 8 cm and consisted of lobules and infiltrating cords of small round malignant cells embedded in a densely hyalinized matrix having both a chondroid and osteoid-like appearance. No definite lacunae or matrix calcification was present. An alveolar pattern was only present focally, and tumor giant cells were not present. One case had a single focus of rhabdomyoblastic differentiation with strap cells. Mitotic activity was >20 mitotic figures/20 high power fields in three of four cases. Immunohistochemically, one case strongly expressed desmin, whereas three cases expressed it focally, with a dot-like pattern. Myogenin was only focally positive, but MyoD1 was present in nearly every cell of each case. Two cases expressed actin and one expressed CD99. No case expressed cytokeratin, S-100 protein, or collagen II. Only one case contained adequate RNA for reverse transcriptase polymerase chain reaction, and this case was negative for the ARMS-associated gene fusions. Follow-up showed one patient to be dead of metastatic disease at 60 months despite intensive therapy, another patient to be disease free at 26 months, and the third patient to be disease free at 5 months. The fourth case is recent. These cases are a distinctive-appearing rhabdomyosarcoma easily mistaken for variants of chondrosarcoma, osteosarcoma, or even sclerosing epithelioid fibrosarcoma because of their hyalinizing appearance compounded by their typically focal and dot-like desmin expression. These four cases are essentially identical to the three unusual RMSs recently reported by Mentzel and Katenkamp as "sclerosing, pseudovascular rhabdomyosarcoma in adults." Although the focal alveolar architecture and the primitive cytologic appearance of these hyalinizing RMS suggest a relationship with ARMS, the presence of abundant strap cells in one case, the predominant expression of MyoD1 rather than myogenin, and the absence of ARMS-associated fusions genes point more strongly toward a variant of ERMS. However, the late adult age in two cases is unusual for both EMRS and ARMS, suggesting that sclerosing RMS may prove to be a distinct subtype of RMS. Study of additional cases will be necessary to more fully elucidate its place among RMS and its prognostic significance.

Fli-1 protein, a member of the ETS family of DNAbinding transcription factors, is involved in cellular proliferation and tumorigenesis. Approximately 90% of Ewing's sarcoma/primitive neuroectodermal tumors (ES/PNET) have a specific translocation, t(11;22)(q24;q12), which results in fusion of EWS to Fli-1, and production of an EWS-Fli-1 fusion protein. We have recently shown that immunohistochemistry for the carboxy terminal of Fli-1 protein is sensitive and highly specific for the diagnosis of ES/PNET. In our earlier study we noted that among normal tissues only endothelial cells and small lymphocytes expressed Fli-1. Fli-1 expression in vascular neoplasms has not been previously studied. Formalin-fixed paraffin-embedded tissue from 54 vascular tumors and 75 nonvascular tumors were immunostained for Fli-1 (1:120, Sc 356, Santa Cruz Biotechnology, Santa Cruz, CA), after steam heat-induced epitope retrieval. Only cases with >10% of cells showing nuclear staining were accepted as positive. Cases without positive internal controls (endothelium and small lymphocytes) were not scored. Positive internal controls were present in 122 of 129 cases (95%). One vascular tumor (Kaposi's sarcoma) and 7 nonvascular tumors (2 epithelioid sarcomas and 5 carcinomas) without internal controls were not scored. Fli-1 was expressed by 50 of 53 vascular tumors scored (94%), including 20 of 22 angiosarcomas, 11 of 12 hemangioendotheliomas, 7 of 7 hemangiomas, and 12 of 12 Kaposi's sarcomas. In contrast, Fli-1 expression was absent in the 68 nonvascular tumors scored (0 of 68), including 16 sarcomas, 7 melanomas, and 45 carcinomas. The results of this study strongly suggest a role for Fli-1 as a novel marker of both benign and malignant vascular tumors. The sensitivity (94%) and specificity (100%) of Fli-1 with regards to the cases evaluated in this study equal or exceed those of the established vascular markers, CD31, CD34, and von Willebrand factor. As the first nuclear, rather than cytoplasmic or membranous marker of endothelium, Fli-1 immunostaining also generally lacks cytoplasmic staining artifacts that are the result of endogenous peroxidases or biotin.

Giant cell angioblastoma was described previously in a single case report as a congenital soft-tissue tumor with a unique morphology. In the current report, we describe three cases of giant cell angioblastoma found in three infants; one case was congenital and located in the hand, one appeared neonatally in the palate, and one on the scalp of an infant. Clinical findings and results of light microscopy, immunohistochemistry, and electron microscopy were evaluated. All tumors were ulcerated; the hand and palate tumors also infiltrated soft tissue and bone. They exhibited a solid, nodular, and plexiform proliferation of oval-to-spindle cells with a frequent striking, concentric aggregation around small vascular channels. These cells had characteristics of undifferentiated mesenchymal cells, fibroblasts, myofibroblasts, and pericytes. Co-mingled with these cells were large mononuclear and multinucleate giant cells with histiocytic features. The palatal giant cell angioblastoma, excised with positive margins, was managed with interferon-alpha and showed no progression after nearly 5 years. The hand tumor diminished in size after management with interferon-alpha, was subtotally excised, and did not progress after 27 months. Follow-up data are unavailable for the patient with the scalp lesion. Our findings validate the classification of giant cell angioblastoma as a distinct and rare entity that is locally infiltrative but slow growing. The morphology and diverse cellular differentiation are consistent with an unusual form of neoplastic angiogenesis.

Schwannomas (neurilemmomas) rarely undergo malignant change, most often in the form of either malignant peripheral nerve sheath tumor (MPNST) or angiosarcoma. We characterize the clinical features and the histopathologic spectrum of 17 schwannomas with evidence of malignant change. The study group comprised 7 males and 10 females with an age range of 16 to 76 years, (median, 40 yrs). None of the patients had neurofibromatosis. Lesions ranged in size from 0.6 to 10.5 cm (median, 4.0 cm) and arose mainly in the limbs/limb girdles (7 cases) or head and neck region (7 cases). All tumors contained areas of conventional benign schwannoma. Four cases of pure epithelioid malignant peripheral nerve sheath tumor (EMPNST) were identified, three of which showed immunopositivity for S-100 protein. Four angiosarcomas were identified, predominantly epithelioid-type. Ten schwannomas had an appearance that we have designated epithelioid malignant change (EMC) and, in one of these, EMC coexisted with EMPNST. Large epithelioid cells with abundant eosinophilic cytoplasm, vesicular chromatin, and prominent nucleoli (morphologically similar to cells of EMPNST) were distributed throughout the schwannoma--singly, in clusters, and in one case a microscopic nodule of such cells was also present. These large epithelioid cells were strongly positive for S-100 protein. Although follow-up data so far are limited, 1 of 5 patients with EMC in whom meaningful follow up was available developed repeated local recurrence (median follow up, 21 mos), one patient each with EMPNST and angiosarcoma died of local and metastatic disease. Pure EMPNST is rare; however, we confirm the tendency of MPNST to show epithelioid cytomorphology when arising in a benign schwannoma. We also confirm the distinctive (albeit infrequent) tendency of angiosarcoma to arise in schwannomas. We describe EMC in schwannomas and suggest that this represents a putative precursor lesion of EMPNST. At this time, we do not have an explanation for the tendency of schwannomas to show epithelioid cytomorphology when they undergo malignant change.

Pulmonary and mediastinal glomus tumors are rare lesions, with four previously reported primary pulmonary cases and three mediastinal cases. The authors report one mediastinal glomus tumor, a locally infiltrative type, and four pulmonary glomus tumors, including the first case of primary pulmonary glomangiosarcoma. These tumors show a variety of clinical and pathologic differences from the more common cutaneous variety, including later age at presentation, larger size, and more frequent atypical/malignant features. Mediastinal and pulmonary glomus tumors both have an average patient age at presentation of 45 years. However, compared with their pulmonary counterparts, mediastinal glomus tumors are less common, more often symptomatic, and are larger (average size, 5.4 cm). Additionally, mediastinal glomus tumors more often demonstrate malignant or atypical features. Pulmonary glomus tumors average 3.3 cm in greatest dimension, with the majority measuring less than 2.5 cm. The pulmonary glomangiosarcoma presented was large, measuring 9.5 cm, and showed increased mitotic count (9 mitoses/10 high-power fields), necrosis, cytologic atypia, and was associated with disseminated disease. Regardless of clinical symptoms, histologic features, and even metastases, the vast majority of all benign and malignant glomus tumors are indolent and cured surgically, with adjuvant therapy needed only for occasional patients with more advanced disease. The four patients with glomus tumors reported are currently alive and free of disease as of last follow up. The patient with the glomangiosarcoma developed widespread metastases and died of disease 68 weeks after initial therapy.

The clinicopathologic features of 12 cases of benign lymphangioendothelioma (acquired progressive lymphangioma) are reported. There were five male and seven female patients. Age at diagnosis ranged from 17 to 90 years (median age, 54 yrs). Development of a single macular/papular hemangiomatous or pigmented lesion was the main presenting symptom. Symptom duration before diagnosis ranged from 2 months to 20 years (median, 5.5 yrs). Tumor size ranged from 0.3 cm to 10 cm (median. 1.5 cm). Location included skin of the head and neck (n = 5), back (n = 1), breast (n = 1), shoulder (n = 1), forearm (n = 1), plantar aspect of the foot (n = 2), and oral mucosa (n = 1). No patient had any other concomitant vascular anomaly (for example, lymphangiomatosis) or was suspected to have acquired immunodeficiency syndrome. Treatment consisted of excisional biopsy in nine patients, incisional biopsy in two, and wide excision in one. Follow-up information on nine patients (range, 4-40 mos; median, 12 mos) showed two local recurrences in one patient. Microscopically, the lesions consisted of anastomosing, often widely dilated vascular structures developing in the superficial dermis. As the lesion grew within deeper dermis, the vascular spaces collapsed and dissected the dermal collagen in an angiosarcoma-like pattern. The lining endothelium was flat and monolayered, with little or no cytologic atypia and no evident mitoses. Some vascular structures contained stromal papillary projections resembling papillary endothelial hyperplasia, and intravascular red blood cells were present occasionally. Immunohistochemistry performed in eight specimens showed variable endothelial cell reactivity for CD31 (7 of 8), CD34 (7 of 7), and factor VIII-related antigen (4 of 6). A smooth muscle cell layer was observed focally around the vascular spaces in six lesions. Benign lymphangioendothelioma (acquired progressive lymphangioma) is an uncommon benign lesion that, in view of major differences in treatment and prognosis, should be distinguished from well-differentiated angiosarcoma and Kaposi's sarcoma, especially the patch stage and lymphangioma-like variants of the latter.

Eight cases of a previously uncharacterized vascular neoplasm, showing varying combinations of benign, low-grade malignant, and malignant vascular components are described. Seven tumors occurred in the dermis and/or subcutis and one occurred in the oral submucosa. The patients were all adults with a median age of 39.5 years (range, 21-71 years). Five patients were men. The tumors arose predominantly in the hands and feet, and the lesions were usually of several years duration. The tumors were composed of a complex admixture of histologic components that varied from tumor to tumor, such that no two tumors looked precisely the same. This was due to variation in the proportions of each component as well as the manner in which each component was distributed throughout each lesion. The predominant histologic components were epithelioid hemangioendothelioma (HE) and retiform HE, which were each present in seven of the tumors. Areas of spindle cell HE were identified in four lesions. Angiosarcoma-like elements were identified in seven tumors. One of the tumors was associated with an arteriovenous malformation and one was associated with an area of lymphangioma circumscriptum. Of six cases with follow up (median duration, 6.5 years), three have recurred locally and, to date, only one has metastasized. We think composite HE is best regarded as a low-grade malignant vascular neoplasm, and the available data suggest that it behaves more favorably than conventional angiosarcoma. The existence of these composite lesions has led to careful reexamination of the concept of HE. The term HE, in that it is currently synonymous with a low-grade malignant vascular tumor, should be reserved for lesions that have true metastatic potential, albeit with low frequency.

Angiosarcoma developed at the site of a Dacron vascular prosthesis 8 years after an aortobifemoral bypass graft insertion. The tumor was composed of epithelioid cells, which showed positive staining for cytokeratin and expression of the common endothelial markers CD31, CD34, and von Willebrand factor. Ultrastructural examination showed aggregates of large cells with intercellular lumina and focal perinuclear whorls of intermediate filaments. The patient, who had abdominal pain and weight loss, died of disseminated pelvic and abdominal disease 6 months after diagnosis. Sarcomas associated with vascular Dacron grafts and angiosarcomas associated with metal or polymer foreign bodies are rare. Their development is probably analogous to the common experimental development of foreign body-associated sarcomas in rodents. Physicians caring for patients with vascular grafts or metal foreign bodies should be aware of this complication.

Immunosuppression in the setting of solid organ transplantation is associated with the development of a variety of malignant tumors, most commonly squamous carcinomas and non-Hodgkin's lymphomas. Sarcomas, apart from Kaposi's sarcoma, are relatively infrequent. We recently encountered a 71-year-old man with chronic renal failure, treated by allograft kidney transplantation, who developed a high-grade epithelioid angiosarcoma at the site of a nonfunctioning arteriovenous fistula, previously constructed for hemodialysis. At diagnosis, the patient had numerous satellite nodules of angiosarcoma involving the distal skin, soft tissues, and bones. After a below-elbow amputation, there was a rapid local recurrence at the amputation stump. Currently, the patient is alive with numerous pulmonary metastases, 6 months after amputation. A literature review identified three recently reported identical cases of epithelioid angiosarcoma arising in nonfunctioning arteriovenous fistulae. All three patients had been treated by kidney transplantation for renal failure, suggesting a possible causal association between these events. We performed polymerase chain reaction for human herpes virus 8, the recently recognized herpes virus proposed as a major etiologic agent of Kaposi's sarcoma, and possibly some conventional angiosarcomas, but we failed to identify any viral DNA within the tumor.

The clinicopathologic, immunohistochemical, and ultrastructural features of soft tissue angiosarcomas are not well defined. Eighty cases of angiosarcoma that involved the deep subcutis, skeletal muscle, retroperitoneum, mesentery, and mediastinum are reported. The lesions occurred in 50 male and 30 female patients who were 5-97 years of age; the peak incidence was in the seventh decade of life. A variety of associated conditions were documented in 20 of these cases, including a history of other neoplasms (some irradiated), synthetic vessel grafts, heritable conditions, and prior trauma or surgery. The angiosarcomas occurred in the extremities (n = 43 cases), trunk (n = 28), and the head and neck (n = 9) regions, with the thigh and the retroperitoneum being the most common sites. They often were characterized as enlarging, painful masses of several weeks' duration and were occasionally associated with acute hemorrhage, anemia, or a coagulopathy. The tumors measured 1-15 cm in diameter (median 5 cm) and frequently were hemorrhagic and multinodular. There was a wide morphologic spectrum within and between cases, including areas similar to cavernous and capillary hemangioma, Dabska tumor, spindle cell and epithelioid hemangioendothelioma, various spindle cell sarcomas, or carcinoma. Histologically, epithelioid angiosarcoma was the most frequently observed pattern; 70% of cases had epithelioid cells that were arranged in nests, clusters, papillae, and gaping vascular channels. Hemorrhage tended to obscure the diagnosis in several cases and often was associated with papillary endothelial hyperplasia-like areas. All 42 cases studied immunohistochemically stained at least focally for Factor VIII-related antigen, and nearly all stained strongly for vimentin, which accentuated the endothelial cells and vessel lumen formation. CD34 antigen was detected in 74% of cases, BNH9 in 72%, and cytokeratins in 35%. Epithelial membrane antigen, S-100 protein, and HMB45 were not detected. Fifty-five percent of the tumors had intracytoplasmic aggregates of laminin. Immunostains for alpha-smooth muscle actin demonstrated a prominent pericytic component in several tumors (24%). Ki67 immunostains with MIB1 indicated high proliferative activity (> or =10%) in 72% of cases. p53 immunoreactivity (>20% nuclear staining) was observed in 20% of cases. Ultrastructural studies performed on poorly differentiated areas of 12 cases showed groups of cells, which were frequently epithelioid, surrounded by basal lamina, and closely associated with pericytes, along with intercellular and intracellular lumina with or without red blood cells. Whorls of abundant intermediate filaments, occasional tonofilamentlike structures, and pinocytotic vesicles also were noted. In contrast to the findings of others, Weibel-Palade bodies were not seen. Follow-up in 49 cases (61%) showed that 53% of patients were dead of disease at a median interval of 11 months, whereas 31% had no evidence of disease at a median interval of 46 months. The remaining patients were either alive with disease (14%) or alive but disease status was unknown (2%). There were local recurrences in 20% of cases and distant metastases in 49%, most frequently to the lungs, followed by the lymph nodes, soft tissues, bone, liver, and other sites. These results indicate that angiosarcoma of soft tissue is a high-grade sarcoma. Older patient age, tumor location in the retroperitoneum, and larger tumor size as well as detection of MIB1 in > or =10% of the tumor cell population were all associated with a poorer prognosis.

Angiosarcoma most frequently occurs in the skin of the head and neck region of elderly persons, lymphedematous limbs, or in deep soft tissue but only rarely has been described to occur in the female genital tract. Four cases of angiosarcoma of the ovary are described herein. They occurred in patients 25 to 42 years old (median, 31 years). The most common clinical presentation was abdominal pain. All of the tumors were unilateral, hemorrhagic, and ranged from 3.5 cm to 14 cm (median, 13 cm). The histologic appearance of the tumors was varied, and often the vascular nature of the tumor was not apparent immediately. Some of the tumors had a fascicular growth pattern composed of spindle-shaped cells with ovoid nuclei and ample eosinophilic cytoplasm closely mimicking leiomyosarcoma. Other tumors resembled ovarian yolk sac tumor with a reticular growth pattern, whereas, in other areas, cystic structures lined by hobnailed hyperchromatic enlarged nuclei simulated clear cell carcinoma of the ovary. Despite these misleading morphologic findings, all cases were characterized, at least focally, by vasoformative channels or discrete cytoplasmic vacuoles, and all were immunoreactive for vascular markers. Two patients with spread of tumor outside of the ovary died 1 month and 2 years after initial diagnosis, respectively. Two patients with tumor confined to the ovary are alive without evidence of disease 3 and 14 months after diagnosis, respectively. The differential diagnosis of this unusual neoplasm is discussed, and the literature is reviewed.

The clinical, gross, microscopic, and immunohistochemical features of four examples of exceedingly rare uterine angiosarcomas reviewed at the Armed Forces Institute of Pathology between 1970 and 1997 are presented. One of the cases described has been reported previously. Based on our findings and a review of the literature, uterine angiosarcomas are aggressive lesions that occur predominately in peri- and postmenopausal women with uterine bleeding and anemia. Grossly, the lesions are of large size at initial presentation with deep myometrial extension. Histologically, the lesions demonstrate characteristic features of angiosarcoma and, when associated with a benign smooth muscle proliferation within the uterus, tend to demonstrate an epithelioid morphology. The immunohistochemical reactivity with CD31, factor VIII, and CD34 and lack of reactivity with smooth muscle actin, keratin, and estrogen receptor confirm the vascular nature of these lesions and exclude the differential diagnostic considerations of carcinosarcoma (MMMT), leiomyosarcoma, adenosarcoma, and hemangiopericytoma. The overall survival of these lesions is poor; the majority of women die of disease within 1 year of diagnosis.

Although vascular invasion is common in many malignant tumors, disseminated intravascular anaplastic neoplasms with occult primary tumor are rare occurrences. Intravascular malignant lymphoma, also called angiotropic lymphoma, is a rare variant of large cell lymphoma predominantly involving vessels in multiple organs, and usually without significant nodal involvement. Although initially misinterpreted as an endothelial neoplasm-angioendotheliomatosis-immunohistochemical studies subsequently proved it to represent a peculiar form of malignant lymphoma. In this report, we describe two patients with extensive intravascular dissemination of angiosarcoma initially without clinically obvious primary tumor. These may be interpreted as examples of true angioendotheliomatosis. In each case the immunohistochemical studies ruled out the most common intravascular malignant neoplasms. The diagnosis of intravascular angiosarcoma was confirmed by the immunoreactivity of the tumor cells to several markers of endothelial lineage in both cases. Thus, angiosarcoma may present with intravascular dissemination and occult primary tumor and closely resemble metastatic carcinoma, melanoma, or angiotropic lymphoma. Immunohistochemical studies are crucial in ruling out these possibilities and in confirming the endothelial origin of the neoplastic cells.

Vascular tumors of the spleen include several different entities, some of which are unique to that organ. Twenty-two such proliferations were studied, including 10 hemangiomas, six littoral cell angiomas, four angiosarcomas, and two hamartomas. The hemangiomas included seven with localized tumors and three with diffuse angiomatosis of the spleen. All cases were studied by paraffin section immunohistochemistry with a large panel of antibodies. In addition, all cases were studied for the presence of the Kaposi's sarcoma-associated herpesvirus (KSHV) using the polymerase chain reaction. The morphologic findings were similar to those previously reported. All proliferations were vimentin positive, and one angiosarcoma was focally keratin positive. All cases reacted for CD31, whereas 20 of 22 were positive for von Willebrand's factor and 19 of 22 were positive for Ulex europeaus. CD34 expression in lining cells was identified in 10 of 10 hemangiomas, two of four angiosarcomas, and one of two hamartomas, whereas all six cases of littoral cell angioma were negative. CD68 was expressed in all cases of littoral cell angioma but was also positive in all three diffuse hemangiomas, two of seven localized hemangiomas, and two of four angiosarcomas. CD21 expression was restricted to the lining cells of littoral cell angioma, and CD8 expression was only identified in two of two hamartomas and two of four angiosarcomas. KSHV was not detected in any of the cases. These findings suggest that there are distinct immunophenotypic as well as morphologic features of splenic vascular tumors. Littoral cell angiomas have a characteristic CD34-/CD68+/CD21+/CD8- immunophenotype and hamartomas have a characteristic CD68-/CD21-/CD8+ phenotype. The frequent CD68 expression in diffuse hemangioma suggests an immunophenotypic difference from localized hemangioma of the spleen.

A breast tumor with features of epithelioid angiosarcoma (EAS) occurring in a 26-year-old woman is described. The lesion on lumpectomy was initially diagnosed as infiltrating ductal carcinoma and treated accordingly by radical mastectomy. The surgical specimen disclosed a high-grade tumor characterized by solid groups and sheets of atypical polygonal epithelioid cells displaying cytoplasmic microlumina alternating with anastomosing vascular channels. The endothelial nature of the epithelioid cells was demonstrated by the presence of vascular endothelium-associated markers by immunohistochemical and ultrastructural studies. The clinical features of this rare, hitherto undescribed lesion are similar to those of conventional breast angiosarcoma. The recognition of this entity is crucial because it can be confused with neoplasms displaying epithelial cytomorphology such as ductal carcinoma, pseudoangiosarcomatous carcinoma, metaplastic carcinoma, and epithelioid hemangioendothelioma. EAS should be added to the list of conditions that may present as a discrete tumor mass of the breast in young women.

Angiosarcomas rarely develop within a peripheral nerve or a peripheral nerve sheath tumor. We describe an epithelioid angiosarcoma that arose in a benign schwannoma (neurilemoma) of the right thigh in a 65-year-old man who did not have von Recklinghausen's disease. Histologically, the resected tumor was a high-grade undifferentiated sarcoma that was predominantly arranged in solid sheets or nests and composed of epithelioid cells. The endothelial origin of the tumor was suggested by Factor VIII R-ag, Ulex europaeus-I, CD34, CD31, BNH9, and vimentin immunoreactivity, along with the ultrastructural evidence of occasional Weibel-Palade bodies. In this location, epithelioid angiosarcoma should be distinguished from malignant transformation of a schwannoma with epithelioid changes. This observation stresses the importance of immunohistochemical and ultrastructural analysis in the differential diagnosis of vascular tumors with features of epithelioid sarcoma.

This report describes a case of a malignant vascular tumor of the spleen with the morphologic, immunologic, and ultrastructural features observed in splenic sinus-lining cells (littoral cells). Histological examination showed a well-differentiated neoplasm forming ectatic blood channels with intraluminal papillary fronds. Tumor cells displayed malignant nuclear features and hemophagocytosis. Solid neoplastic areas with mitotic figures were present. Ultrastructurally, the tumor cells showed the concomitant presence of lysosomes and Weibel-Palade bodies. Immunohistochemically, the tumor cells were positive for both endothelial (Factor VIII-AG, CD34) and histiocytic markers (cathepsin D, lysozyme, alpha-1-antichimotrypsin). Our results indicate that angiosarcoma may originate from all the vascular compartments of the spleen, including red-pulp sinuses, and may have morphologic and immunophenotypic similarities to littoral cell angioma, a recently described benign vascular tumor of the spleen.