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The clinical evolution of solitary fibrous tumor (SFT) remains unclear. Although various clinical, morphological and molecular criteria may indicate increased risk of malignancy, some SFT can still progress despite having a clearly benign appearance. Various risk stratification systems have been proposed, but unfortunately they are not sufficient to precisely determine the malignant potential. In this review, we discuss current knowledge on SFT, focusing on the following controversial issues: (i) the diverse morphologic spectrum: 'the great simulator;' (ii) malignant transformation or dedifferentiation; (iii) current risk stratification systems; and (iv) molecular factors associated with clinical evolution. The morphological spectrum of SFT and the list of differential diagnoses continue to expand. Both have increased considerably since the first descriptions of specific molecular alterations. A classification of malignant SFT should not be based on histology alone. The correlation of all pathological and molecular factors is recommended; its inclusion in risk stratification systems may help to improve diagnosis and prognosis.

Solitary fibrous tumors (SFTs) are a rare type of mesenchymal lesion in which specific clinicopathologic factors have been related to patient outcome. We collected clinical, pathological, and molecular data of 28 patients with histologically confirmed SFT having at least one pathological factor associated with aggressive behavior. Molecular analysis to detect NAB2/STAT6 gene fusion, TP53, and/or TERT promoter mutation was performed. We analyzed the pathological factors predictive of recurrence/metastasis and compared with clinical outcome. The risk of metastasis was calculated using four previously described scoring systems. Histopathologically, all tumors revealed hypercellularity, 11 had ≥ 4 mitoses/10 HPF, and 12 showed necrosis. Dedifferentiation was observed in three tumors. STAT6 was positive in all cases. Desmin, p16, INSM1, and HTER immunoexpressions were detected in 14, 18, 21, and 46% of the SFT, respectively. The NAB2/STAT6 gene fusion was detected in 16 tumors. After a median follow-up of 34 months, 32.0% recurred, 32.1% metastasized, and 35.7% died of disease. TERT mutations were detected in almost half the tumors. Tumors with TP53 mutations or with TP53 and TERT promoter mutations were almost always classified as high risk, and the patients developed metastases and/or died of disease. Tumors with intermediate-risk and TERT mutation had a worse evolution. SFTs with adverse pathological parameters were not always related with a poor outcome, thus confirming the unpredictable clinical behavior of SFT. The inclusion of molecular factors (TP53 and TERT promoter status) may provide new prognostic indicators for future risk stratification systems, especially in the intermediate-risk group.

The diagnosis of Ewing sarcoma requires the integration of the information generated from numerous techniques, some of them being very sophisticated. However, the first steps of the diagnostic process are crucial to achieve the maximum possible diagnostic performance. In this chapter we will review how to handle the diagnostic specimen from its collection, how to prepare it for diagnosis, how to make a complete pathology report, and provide guidance for the reasonable use of immunohistochemical techniques in this malignancy.

Background Despite extensive immunohistochemical (IHC) and molecular studies combined with morphologic findings, a group of round/ovoid cell tumors histologically similar to Ewing sarcomas (ES) but lacking EWSR1-rearrangements may remain unclassifiable. Design We retrospectively analyzed 41 Ewing-like tumors (formalin-fixed, paraffin-embedded) previously determined as negative or non-informative for EWSR1-rearrangements by FISH and/or RT-PCR. A new histopathology revision and additional IHC and molecular analyses were carried out in order to investigate whether additional IHC and/or molecular testing in combination with the morphological findings may help in reaching a definitive diagnosis. Results Almost all the tumors (n = 40) involved soft tissue and/or bone and half the patients died of disease. In the archival cases all diagnoses were Ewing sarcoma (ES), Ewing-like sarcoma (ELS), myoepithelial tumor and undifferentiated sarcoma (US). In the new review all the tumors were re-classified as, ES (n = 16), Ewing-like tumor with EWSR1 rearrangement and amplification and possible EWSR1-NFATC2 gene fusion (n = 1), CIC-rearranged sarcomas or undifferentiated sarcoma, most consistent with CIC-rearranged sarcoma (n = 7), sarcoma with BCOR-alteration or undifferentiated sarcoma, consistent with BCOR-associated sarcoma (n = 3), neuroblastoma (n = 2), unclassifiable neoplasm with neuroblastic differentiation (n = 1), malignant rhabdoid tumor (n = 2), lymphoblastic lymphoma (n = 1), clear cell sarcoma of the gastrointestinal tract (n = 1), small cell carcinoma (n = 1), sclerosing rhabdomyosarcoma (n = 1), desmoplastic small round cell tumor (n = 1), malignant peripheral sheath nerve tumor (n = 1), poorly-differentiated synovial sarcoma (n = 1), Possible gastrointestinal stromal tumor/GIST with predominant round cells (n = 1) and possible SMARCA4-deficient-sarcoma (n = 1). NKX2.2, ETV4 and BCOR immunoreactivity was observed in all ES, CIC-rearranged sarcomas and sarcomas with BCOR alteration, respectively. CIC-rearrangement by FISH was observed in many of the CIC-rearranged sarcomas. Conclusion Our analysis of 41 Ewing-like tumors confirms that there may be a significant pathological and IHC overlap among Ewing-like tumors, with prognostic and therapeutic impacts. Additional IHC (NKX2.2, ETV4 and BCOR) and molecular studies including FUS, CIC or BCOR analysis may support the final diagnosis when FISH or RT-PCR fail to detect EWSR1-rearrangements. Any molecular findings should always be interpreted in relation to the specific clinical and pathological context.

Ewing sarcoma is an aggressive neoplasm of pediatric and adolescent patients. Immunohistochemistry (IHC) can be used to support the morphologic diagnosis of Ewing sarcoma family of tumors (ESFT) in a convincing clinical/radiological context. Although neither NKX2.2 nor CD99 alone are entirely specific, when combined, the diagnostic specificity is high. The aim of the present study was to investigate the IHC expression of NKX2.2, ETV4 and BCOR in a large series of genetically confirmed ESFT. The results for CD99 and CAV-1 immunoreactivity, and the histological and fusion gene subtypes were retrieved from our previous study. NKX2.2 demonstrated moderate or strong nuclear positivity in 91.2% of the tumors. The staining intensity was heterogeneous. Many of the ESFT with negative NKX2.2 immunoreactivity were in bone. Strong/moderate ETV4 nuclear expression was detected in two small round cell tumors, both were negative for NKX2.2. No relationships could be found between expression of NKX2.2 and the histological subgroups or ESFT gene fusion subtypes. BCOR was negative in all ESFT. In conclusion, NKX2.2, ETV4 and BCOR IHC may be helpful in daily practice for distinguishing ESFT from CIC or BCOR-associated sarcomas, especially in hospitals without access to molecular assays. In addition, the combination of strong CD99 membranous positivity and nuclear NKX2.2 positivity seems to be very reliable for ESFT diagnosis in an appropriate clinicoradiological setting. So far no antibody is entirely specific for ESFT diagnosis, and the IHC or molecular results in round cell tumors of bone may be strongly influenced by decalcification processes.

Desmoplastic melanoma (DM) and cutaneous malignant peripheral nerve sheath tumors (MPNST) reveal histological and immunohistochemical similarities, including S100 positivity and negative staining for conventional melanocytic markers. We present 3 cases of cutaneous S100-positive spindle cell tumors in elderly patients, in which first findings led to initial misdiagnoses as cutaneous MPNST and benign peripheral sheath nerve tumor (neurofibroma). The identification of adjacent atypical melanocytic hyperplasia in the overlying skin along with tumor cell proliferation, also in the superficial dermis, the neurotropic component and the absence of any relationship between the tumor and a major nerve, pre-existing neural benign tumor or the existence of stigmata suggestive of neurofibromatosis raised consideration of a DM. Careful attention should be paid to the presence of a firm dermal nodule and atypical scar lesions especially in sun-exposed areas (mainly head and neck region) in elderly patients associated with S100-positive spindle cell proliferation, solar elastosis and adjacent atypical melanocytic proliferation. In such cases, the possibility of a DM should be excluded with caution, especially if the tumor reveals a paucicellular morphology resembling various non-melanocytic neoplasms including malignant or benign peripheral sheath nerve tumors.

SATB2 is commonly expressed in osteosarcomas. Although apparently being a valuable diagnostic marker for differentiating between small cell osteosarcoma (SCO) and other small round cell tumors of bone, for instance Ewing sarcoma family of tumors (ESFT), it has not been tested in a large series of ESFT and chondrosarcomas so far. We studied the immunohistochemical expression of SATB2 in 42 osteosarcomas, 31 chondrosarcomas, and 371 genetically confirmed ESFT. SATB2 positivity was detected in 90.4% of osteosarcomas, 87.5% of SCO, 91.3% of osteoblastic osteosarcomas, and in all chondroblastic and parosteal osteosarcomas. The osteoblastic and SCO subtypes expressed SATB2 more intensely than other histological types. SATB2 was expressed in 46.6% of chondrosarcomas, and in 1.3% of ESFT. Sensitivity and specificity of SATB2 immunoexpression were 90.4% and 95.3%, respectively. The positive and negative predictive values in osteosarcoma diagnosis were 66.6% and 98.9%, respectively. In chondrosarcoma, SATB2 immunoexpression was more frequent and intense in high-grade chondrosarcoma (Grade III) and uncommon in chondrosarcoma grade I. SATB2 positivity was detected in 55.6% of chondrosarcomas grade II. SATB2 apparently cannot distinguish between chondroblastic osteosarcoma and high-grade chondrosarcoma. Nevertheless, SATB2 is frequently expressed in osteogenic tumors, but is rarely positive in ESFT, and with the support of CD99 expression and specific molecular studies, it is very useful for distinguishing between these two lesions. Although SATB2 immunoexpression helps to distinguish osteosarcoma from their mimickers, the identification of malignant osteoid matrix formation and the integration of clinical and radiological data remain the corner stone of osteosarcoma diagnosis and as yet no antibody has equalled the diagnostic value of this important morphologic hallmark.

Hyaline globules and papillary fragments in cytologic samples from two intra-abdominal tumors in young females are presented including the cytological features and the correlation with the histopathologic and immunohistochemical findings. In the first case a cytologic study from an ovarian mass showed papillary structures and isolated tumor cells with epithelioid morphology, irregular reniform-like nuclear contour, pale or vacuolated cytoplasm, abundant hyaline globules and occasional glomeruloid structures resembling Schiller-Duval bodies. Yolk sac tumor (YST) was the diagnosis on the histological slides. Tumor cells showed positivity for cytokeratin (AE1/AE3), epithelial membrane antigen (EMA), alpha-fetoprotein (AFP) and Sal-like protein 4 (SALL4). In case number two the cytologic study from a liver metastasis displayed papillary and rosette-like clusters composed of uniform and bland cells showing occasional long cytoplasmic tails, hyaline globules and nuclear grooves. A diagnosis of hepatic metastasis from solid pseudopapillary neoplasm of the pancreas (SPNP) was rendered from the histology. Tumor cells revealed immunoreactivity for cytokeratin (AE1/AE3), Vimentin, Galectin-1 (GAL-1), Neuron specific-enolase, CD10, progesterone and β-catenin (nuclear stain). Regarding differential diagnosis, in the patient with the ovarian mass an ovarian clear cell carcinoma was considered, as well as other germ cell tumors or metastatic carcinoma, while in the patient with a liver metastasis a neuroendocrine carcinoma was taken into account. YST and SPNP share some cytological findings, including hyaline globules, papillary structures, clear cells and intercellular eosinophilic basement membrane deposits. Thus, a detailed study and careful interpretation of the cytological, histological and immunohistochemical findings may be worthwhile to avoid a potential misdiagnosis, particularly in the cytologic specimens of the ovarian and/or intra-abdominal mass, when involving young females. Diagn. Cytopathol. 2016;44:935-943. © 2016 Wiley Periodicals, Inc.

Background Differentiation of Ewing sarcoma family of tumors (ESFT) and Ewing-like tumors remains problematic. Certain ESFT with morphological and immunohistochemical (IHC) profiles lack the EWSR1-ETS transcript. To improve diagnostic accuracy we investigated the presence of several specific transcripts in 200 small round cell tumors (SRCT) displaying ESFT morphology and immunophenotype in which EWSR1 FISH analysis was non-informative or negative. Design 200 tumors (formalin-fixed, paraffin-embedded) were analyzed by RT-PCR. All tumors were tested for EWSR1-ETS , EWSR1 / WT1 , PAX3 / 7-FOX01 or SYT / SSX transcripts, and the negative tumors were subsequently analyzed for CIC / DUX4 , BCOR / CCNB3 and CIC / FOX04 transcripts. Results 133 (66.5%) ESFT displayed one of the above EWSR1-ETS translocations. Three cases (1.5%) revealed the SYT-SSX transcript for Synovial sarcoma, and one (0.5%) a EWSR1-WT1 transcript for Desmoplastic Small Round Cell tumor. The CIC-DUX4 translocation was found in six Ewing-like tumors (3%) with CD99 positivity. The BCOR-CCNB3 gene fusion was observed in 5 tumors (2.5%) displaying round or spindle cells with strong CCNB3 IHC expression in 3 tumors. Moreover, RT-PCR failed to detect any gene fusion transcripts in 19 tumors (9.5%) and were considered "undifferentiated small round cell sarcoma" (SRCS). Molecular biology results were non-informative in 33 SRCTs (16.5%) due to RNA degradation through inadequate fixation and/or decalcification. Conclusion Our analysis of 200 SRCTs confirms the molecular heterogeneity of neoplasms with ESFT morphology and highlight that molecular studies with RT-PCR including new emerging gene fusion transcripts are mandatory for the diagnosis when EWSR1 FISH is negative or non-informative. The incidence of CIC-DUX4 , BCOR-CCNB3 and CIC-FOX04 transcripts was relatively low. A small group of Ewing-like sarcomas or undifferentiated SRCS remains unclassified. Adopting appropriate tissue fixation and processing protocols is important to avoid degradation of fixed/embedded tissue when no frozen tumor is available.

Neuroendocrine differentiation or aberrant expression of neuroendocrine markers is very uncommon in angiosarcomas (AS) and creates a challenging differential diagnosis with other superficial or soft tissue tumors. Herein, we report a new case of superficial AS presenting as a tumor lesion on the little finger of the right hand of a 52-year-old man. The tumor displayed CD56, chromogranin-A, and synaptophysin immunoreactivity. Tumor cells were positive for vascular markers (CD31, FLI1, ERG, D2-40, VE-cadherin, VEGR1,2, and 3), CD99, and EMA, but were negative for S100, CK (AE1/AE3), CK20, polyomavirus, and myogenic (desmin and myogenin) and melanocyte markers (melan-A and HMB45). Ki67 immunostains indicated high proliferative activity (>50%). The whole-body computed tomography did not reveal distant disease. The initial assessment considered several tumor subtypes as possible histological diagnoses, including Ewing sarcoma, Ewing-like sarcoma, Merkel cell carcinoma, and undifferentiated "small round cell sarcoma". Fluorescence in situ hybridization analysis was negative for EWSR1 translocation and molecular analysis failed to detect any EWSR1, CIC, SYT or BCOR rearrangement. As a follow-up investigation, we tested 17 cutaneous/superficial AS for neuroendocrine markers; however, only one of these showed focal CD56 and synaptophysin expression. In conclusion, the present findings indicate that neuroendocrine differentiation is a very infrequent feature in AS. We report an AS of the finger with an uncommon histological appearance and immunohistochemical profile: predominant round cell tumor proliferation and neuroendocrine differentiation. Pathologists should be aware of these potential histological and immunohistochemical pitfalls in AS.

Epithelioid hemangioma (EH) is a rare benign vascular lesion, characterized by endothelial cells with epithelioid/histiocytoid appearance. Heart involvement is extremely rare. We present an unusual case of cardiac EH in a young woman with supraventricular arrhythmia, nephrotic syndrome (membranous glomerulopathy), and peripheral eosinophilia after a pregnancy and normal partum resembling Kimura disease. Echocardiogram showed a large tumor mass in the right cardiac ventricle. The cardiac tumor was removed and the histopathology revealed an endothelial proliferation associated with abundant eosinophils. The neoplastic endothelial cells were eosinophilic and polygonal with epithelioid/histiocytoid morphology. Lymphoid nodules were occasionally seen. The neoplastic cells were positive for CD34, CD31, ERG, and factor VIII and negative for CK. A diagnosis of EH was rendered. The patient was alive and well after surgical resection. EH and Kimura disease represent separate entities, but clinical and/or histological overlapping can be observed. Epithelioid/histiocytoid endothelial cells constitute the hallmark feature that favors a final diagnosis of EH.

A new case of soft tissue myoepithelial carcinoma (MEC) with rhabdoid-like differentiation is presented including cytologic, histopathologic, immunohistochemical, and molecular biologic features. A 45-year-old woman was admitted to the Hospital with nodular mass involving the lower part of the abdominal wall. Fine-needle aspiration cytology showed a round cell tumor with abundant cytoplasm in the myxoid background. The nuclei were uniform, round to ovoid, with finely distributed chromatin, nucleoli, and pale, vacuolated, or eosinophilic cytoplasm with rhabdoid-like appearance resembling a soft tissue malignant rhabdoid tumor. The surgically removed tumor was poorly demarcated, yellow, soft, and myxoid. The histopathology revealed sheets of poorly differentiated round malignant cells with focal myxoid stroma and rhabdoid-like morphology. Immunohistochemistry showed positivity for CK (AE1/AE3), EMA, S100, vimentin, CD99, and SMA; however desmin, CD34, and gliofibrilar acid protein (GFAP) were negative. Tumor cells revealed loss of INI1 expression. The EWSR1 gene rearrangement was detected by fluorescence in situ hybridization (FISH), but molecular biology failed to detect EWSR1/ETS, EWSR1/NR4A3, EWSR1/DDIT3, EWSR1/ATF1, EWSR1-POU5F1, EWSR1/ZNF444, EWSR1-PBX1 gene fusions. The final diagnosis was soft tissue malignant myoepithelioma with rhabdoid changes and EWSR1 gene rearrangement. The differential diagnosis included soft tissue malignant rhabdoid tumor, cellular extraskeletal myxoid chondrosarcoma, proximal epithelioid sarcoma, and other soft tissue tumor with EWSR1 rearrangement. To our knowledge, this is the first case of MEC with rhabdoid features and description of fine-needle aspiration cytology.

Sinonasal tract (SNT) alveolar rhabdomyosarcoma (ARMS) are frequently misdiagnosed, especially in adults. Fifty-two adult (≥18 years) patients with SNT ARMS were reviewed and characterized by immunohistochemistry and molecular studies. Twenty-six females and 26 males (18–72 years; mean 43.2 years), presented after a short duration (mean 2.6 months) with a large (mean 5.5 cm) destructive nasal cavity mass, involving multiple contiguous paranasal sites (n = 46) and with cervical adenopathy (n = 41). The tumors showed an alveolar, nested to solid growth pattern below an intact, but often involved (n = 9) epithelium with frequent necrosis (n = 37), destructive bone invasion (n = 30), and lymphovascular invasion (n = 25). The neoplastic cells were dyshesive and dilapidated, with crush artifacts. Rhabdoid features (n = 36) and tumor cell multinucleation (n = 28) were common. Mitotic counts were high (mean 17/10 HPFs). The neoplastic cells showed the following immunohistochemical positive findings: desmin (100%), myogenin (100%), MYOD1 (100%), MSA (96%), SMA (52%), CAM5.2 (50%), AE1/AE3 (36%); other positive markers included S100 protein (27%), CD56 (100%), synaptophysin (35%), and chromogranin (13%). Overall, 54% show epithelial marker reactivity. Molecular studies showed FOXO1 translocations (81%) with PCR demonstrating PAX3 in 72.7% tested. Patients presented with high stage (IV 24; III 26) and metastatic disease (lymph nodes n = 41; distant metastases n = 25) (IRSG grouping). Surgery (n = 16), radiation (n = 41) and chemotherapy (n = 45) yielded an overall survival of 36.1 months (mean; range 2.4–286); 18 alive without disease (mean 69.6 months); 7 alive with disease (mean 11.0 months); 1 dead without disease (63.7 months); and 26 dead with disease (mean 18.5 months). SNT ARMS frequently present in adults as a large, destructive midline mass of short symptom duration, with high stage disease. The alveolar to solid pattern of growth of cells with rhabdoid-plasmacytoid features suggests the diagnosis, but epithelial immunohistochemistry markers are present in 54% of cases, leading to misdiagnosis as carcinomas if muscle markers are not also performed. Overall survival of 36.1 months is achieved with multimodality therapy, but 64% have incurable disease (16.9 months). Mixed anatomic site (p = 0.02) was a significant adverse prognostic indicator, while stage (0.06) and tumor size >5 cm (0.06) approached marginal significance.

Perivascular epithelioid cell tumors (PEComas) are infrequent neoplasms with peculiar myomelanocytic differentiation. The aggressive abdominopelvic variant is rare, with only a small number of published cases. We present an additional case of this unusual variant, which showed an aggressive histologic and clinical behavior with multiple liver metastases and resistance to several therapies. We also discuss the histological and immunohistochemical profiles as well as the differential diagnosis.

Background: Gastrointestinal stromal tumour (GIST) is the most common primary mesenchymal tumour of the gastrointestinal tract. Spindle cell monophasic synovial sarcoma (SS) can be morphologically similar. Angiogenesis is a major factor for tumour growth and metastasis. Our aim was to compare the angiogenic expression profiles of high-risk GIST and spindle cell monophasic SS by histological, immunohistochemical and molecular characterisation of the neovascularisation established between xenotransplanted tumours and the host during the initial phases of growth in nude mice. Methods: The angiogenic profile of two xenotransplanted human soft-tissue tumours were evaluated in 15 passages in nude mice using tissue microarrays (TMA). Tumour pieces were also implanted subcutaneously on the backs of 14 athymic Balb-c nude mice. The animals were sacrificed at 24, 48, and 96 h; and 7, 14, 21, and 28 days after implantation to perform histological, immunohistochemical, and molecular studies (neovascularisation experiments). Results: Morphological similarities were apparent in the early stages of neoplastic growth of these two soft-tissue tumours throughout the passages in nude mice and in the two neovascularisation experiments. Immunohistochemistry demonstrated overexpression of proangiogenic factors between 24 h and 96 h after xenotransplantation in both tumours. Additionally, neoplastic cells coexpressed chemokines (CXCL9, CXCL10, GRO, and CXCL12) and their receptors in both tumours. Molecular studies showed two expression profiles, revealing an early and a late phase in the angiogenic process. Conclusion: This model could provide information on the early stages of the angiogenic process in monophasic spindle cell SS and high-risk GIST and offers an excellent way to study possible tumour response to antiangiogenic drugs.

The developmental receptor NOTCH plays an important role in various human cancers as a consequence of oncogenic mutations. Here we describe a novel mechanism of NOTCH-induced tumor suppression involving modulation of the deacetylase SIRT1, providing a rationale for the use of SIRT1 inhibitors to treat cancers where this mechanism is inactivated because of SIRT1 overexpression. In Ewing sarcoma cells, NOTCH signaling is abrogated by the driver oncogene EWS-FLI1. Restoration of NOTCH signaling caused growth arrest due to activation of the NOTCH effector HEY1, directly suppressing SIRT1 and thereby activating p53. This mechanism of tumor suppression was validated in Ewing sarcoma cells, B-cell tumors, and human keratinocytes where NOTCH dysregulation has been implicated pathogenically. Notably, the SIRT1/2 inhibitor Tenovin-6 killed Ewing sarcoma cells in vitro and prohibited tumor growth and spread in an established xenograft model in zebrafish. Using immunohistochemistry to analyze primary tissue specimens, we found that high SIRT1 expression was associated with Ewing sarcoma metastasis and poor prognosis. Our findings suggest a mechanistic rationale for the use of SIRT1 inhibitors being developed to treat metastatic disease in patients with Ewing sarcoma. Cancer Res; 74(22); 6578–88. ©2014 AACR.

The present study describes a new case of EWSR1-negative undifferentiated sarcoma with CIC/DUX4 gene fusion. This case is similar to tumors described as primitive undifferentiated round cell sarcomas that occur mainly in the trunk and display an aggressive behavior. To our knowledge, this is the first report of such a tumor presenting locoregional lymph node metastasis. In view of previous studies that prove the existence of a particular variant of undifferentiated sarcoma with Ewing-like morphology and CIC/DUX-4 gene fusion, a search for this gene fusion in all undifferentiated round cell sarcomas should be considered if a conclusive diagnosis cannot be reached following other conventional studies. Although additional cases with more extensive follow-up studies are needed, we believe that EWSR1-negative undifferentiated small round cell sarcoma with CIC/DUX4 gene fusion should be added to the list of new sarcoma variants with the possibility of lymph node metastasis.

Galectin-1 (GAL-1) is frequently expressed in osteosarcomas. Although a valuable diagnostic marker to differentiate between chondroblastic osteosarcomas and conventional chondrosarcomas, it has not been tested in the Ewing sarcoma family of tumors (ESFTs). We studied by immunohistochemistry GAL-1 expression in 43 osteosarcomas, 23 chondrosarcomas, and 217 genetically confirmed ESFTs using a tissue microarray. GAL-1 was expressed in 78 % of osteosarcomas, 33 % of chondrosarcomas, and 8 % of ESFTs. Osteoblastic and small cell osteosarcoma subtypes expressed GAL-1 in a high percentage of cells when compared with the other histological subtypes, whereas two chondroblastic osteosarcomas were negative. GAL-1 was mainly expressed in high-grade chondrosarcomas (grade III). ESFTs were rarely positive (8 %), and this was not related to the histological subtype nor to the clinical outcome. Although GAL-1 expression distinguishes chondroblastic osteosarcomas from conventional chondrosarcomas and is usually negative in conventional chondrosarcomas, the final diagnosis needs to incorporate histopathology since some chondroblastic osteosarcomas fail to express GAL-1, while high-grade chondrosarcomas are GAL-1 positive. Since GAL-1 is frequently expressed in osteogenic tumors, including small cell osteosarcoma, but rarely positive in ESFTs, its expression seems a valuable tool for distinguishing between these lesions. GAL-1 immunoexpression is not indicative of prognosis in ESFT.

The objectives of this work are to study angiogenesis in pancreatic ductal adenocarcinoma using computerized morphometric and image analysis and to compare the microvascular density in intratumoral and peritumoral areas and normal pancreatic tissue. Microvascular density was analyzed in 60 cases of pancreatic ductal adenocarcinoma and 30 samples of normal pancreatic tissue using an avidin-biotin immunoperoxidase technique with an anti-CD31 antibody. Microvascular density (MVD) was analyzed through digital microimaging and computerized analysis. The blood vessel density in the tumor was significantly higher than in peritumoral areas and in normal pancreatic tissue. Well differentiated pancreatic ductal adenocarcinomas contained higher MVD than poorly differentiated carcinomas. In pancreatic adenocarcinoma, MVD is higher than in peritumoral tissue or normal pancreatic tissue.

Superficial/cutaneous small round-cell tumors comprise a heterogeneous group of neoplasms including sarcoma, carcinoma, melanoma, and lymphomas. Among superficial sarcomas, the Ewing's sarcoma family of tumors (ESFT) represents a poorly understood rare variant, having a behavioral difference characterized by a relative favorable prognosis. Several problems are still to be resolved in superficial ESFT, including the differential diagnosis between ESFT of bone (intraosseous or periosteal) with superficial infiltration and superficial ESFT with bone infiltration, especially in the fingers. Our aim is to review the most common types of small round-cell tumors included in the differential diagnosis of superficial ESFT, analyzing the histopathology, phenotype, and molecular alterations of each entity.

During the 25-year period subsequent to the Chernobyl accident, the morbidity of malignant renal tumors in Ukraine has increased from 4.7 to 10.7 per 100,000 of the total population. Recent studies of our group have shown that increases in morbidity, aggressiveness, and proliferative activity of renal cell carcinomas (RCCs), especially clear-cell renal cell carcinoma (CCRCC), in Ukrainian patients continuously inhabiting the radio-contaminated areas could be explained by specific molecular changes influenced by the so-called "chronic persistent low-dose ionizing radiation" (CPLDIR) exposure. This study aimed to examine the role of angiogenesis in CCRCC carcinogenesis associated with CPLDIR in patients living more than 20 years in cesium 137 ((137)Cs) contaminated areas after the Chernobyl accident in Ukraine. Paraffin-embedded specimens of 106 CCRCs were studied: Control cases were 18 tumors from Spanish patients (group 1), 25 tumors from Ukrainian patients from so-called clean areas without known radio-contamination (group 2), and 63 tumors from Ukrainian patients from radio-contaminated areas (group 3). For intratumoral microvessel density (MVD) determination, anti-CD31 antibody was used. A computerized image analysis program was used to quantitatively calculate the vascular density. Seventy-three percent of group 3 and 72 % of group 2 CCRCCs displayed the highest MVD. A striking increase in MVD was seen in group 3 CCRCCs, in comparison with groups 1 and 2 (p 0.001). The majority of the hot spot vessels in group 3 was poorly differentiated. Moreover, MVD values for total vessels as well as for capillaries and tumor grade were strongly correlated. When we compared only tumor-node-metastasis tumor stages I and II, the differences remained statistically significant (p 0.1). The ratio of the average total vessels and capillaries in the Ukrainian groups combined was 1.65:1 in comparison to the Spanish group. Our results provide evidence that CPLDIR exposure increases MVD (particularly capillary) in CCRCCs and is associated with a higher histological grade.

Chondrosarcomas are malignant cartilage-forming tumors that represent the third most common malignant solid tumor of bone. In patients with grades II and III, local recurrence, increasing tumor size and dedifferentiation have been associated with lower survival rates. These biologically poorly-understood neoplasms vary considerably in clinical presentation and biological behavior. Cytogenetic studies have shown that heterogeneity is related to karyotypic complexity; moreover, alterations in the 9p21 locus and TP53 gene are related to disease progression. Despite the relatively high frequency of chondrosarcoma only a limited number of cell lines exist in the scientific community, limiting the possibility to study hypothesis-derived research or primary drug interaction necessary for pre-clinical studies. We report a chondrosarcoma cell line, CH-3573, derived from a primary tumor that may serve as a useful tool for both in vitro and in vivo models to study the molecular pathogenesis. In addition, xenograft passages in nude mice were studied to characterize the genetic stability over the course of tumor progression. In contrary to other reported cell lines, an important feature of our established cell line was the retained matrix production, a characteristic feature of a conventional grade II chondrosarcoma. The cell line (CH-3573) was characterized by pathological, immunohistochemical and molecular genetic methods.

Pleomorphic hyalinizing angiectatic tumor (PHAT) is an uncommon soft tissue tumor usually located in extremities or trunk. We report 3 new cases with histopathologic diagnosis of PHAT, one with recurrence and sarcomatous myxofibrosarcoma component and another with unreported soft tissue palpebral location. Clinical data, histopathology, immunohistochemistry, fluorescence in situ hybridization, and follow-up data are described. The histopathology showed a tumor with angiectatic blood vessel proliferation and perivascular hyaline material associated with focal pleomorphic cells. The recurrent tumor revealed a histopathologic pattern corresponding to a myxofibrosarcoma. Vimentin and CD99 were positive in tumor cells and CD34 was strongly positive in the tumor cells from the recurrence. Ki-67 was poor positive but with increased positivity in the recurrence. The positivity of p53 and chromosome 22 polysomy were detected in the recurrence. At present, the 3 patients are free of disease and no metastases have been detected. Indeed, the possibility that PHAT may represent a histopathologic pattern and not a true neoplastic entity with specific genetic alterations cannot be excluded at present, and further studies are required.

Background Dermatofibrosarcoma protuberans (DFSP) is an uncommon cutaneous tumor, usually low grade, except for the fibrosarcomatous variant (DFSP-FS). Objectives We sought to compare the clinicopathological, immunohistochemical, genetic, and therapeutic features between DFSP and DFSP-FS. Methods The clinicopathological features were reviewed in 63 DFSP and 12 DFSP-FS. Immunohistochemistry and multiplex reverse transcriptase-polymerase chain reaction were carried out using formalin-fixed, paraffin-embedded tissue, using specific primers for collagen type I alpha 1 ( COL1A1 ) and platelet-derived growth factor beta ( PDGFB ). Results DFSP-FS was associated with tumor history longer than 5 years ( P = .009), tumor size greater than 4 cm ( P = .001), more stages of modified Mohs micrographic surgery ( P = .005), expansive subcutaneous infiltration ( P = .005), muscular invasion ( P = .0001), absence of CD34 staining ( P = .018), p53 positivity ( P = .006), and increased proliferative activity ( P = .004) compared with DFSP. The COL1A1-PDGFB fusion transcript was found in 100% DFSP-FS and 72% DFSP. No association was found between the different COL1A1-PDGFB fusion transcripts and the different histologic subtypes. Wide local excision (2 cm) was performed in 47% of cases and modified Mohs micrographic surgery in 53%. After a mean follow-up of 73 months (range 21-235), 6 patients had local recurrence (5 DFSP, 1 DFSP-FS) and one died of disease (DFSP-FS). The only factor related to local recurrence was the type of surgery (17% wide local excision vs 0% modified Mohs micrographic surgery) ( P = .006). Limitations Our study is retrospective. Prospective studies are necessary to confirm our results. Conclusions DFSP-FS reflects tumor progression in DFSP, with larger size, particular invasive patterns, p53 expression, and increased proliferative activity. However, as in low-grade DFSP, appropriate surgery permits a tumor-free excision. COL1A1-PDGFB is a useful tool for diagnosis of DFSP and particularly for DFSP-FS.

Notch can act as an oncogene or as a tumour suppressor and thus can either promote or inhibit tumour cell growth. To establish Notch status in Ewing's sarcoma family of tumours (ESFT), we investigated the Notch pathway by gene expression profiling meta-analysis or immunohistochemistry in samples obtained from 96 and 24 ESFT patients, respectively. We found that although Notch receptors were highly expressed, Notch did not appear to be active, as evidenced by the absence of Notch receptors in cell nuclei. In contrast, we show that Notch receptors known to be active in colon adenocarcinoma, hepatocarcinoma, and pancreatic carcinoma stain cell nuclei in these tumours. High expression of the Notch effector HES1 transcription factor, usually used as a surrogate marker for active Notch, was also restricted to outside of the nucleus in the majority of ESFT, and analysis of HES1 gene targets indicated HES1 to be transcriptionally inactive. Neither forced activation nor pharmacological or genetic blocking of Notch affected HES1 expression in ESFT cells, indicating HES1 expression to be uncoupled from the Notch pathway. Additional functional studies in ESFT cell lines confirmed Notch to be switched off. Finally, unlike experiments in which HES1 expression was modulated, experimental activation of Notch in ESFT cell lines via several means blocked cell proliferation and reduced their clonogenic potential in soft agar. These indicate that HES1 is uncoupled from Notch in ESFT, that EWS-FLI1-mediated inhibition of Notch contributes to ESFT aggressive cell growth, and support a role for Notch in ESFT tumour suppression, at least partly through the Notch effector HEY1.

BACKGROUND: Human tumors transplanted into immunodeficient mice (xenografts) are good preclinical models, and it is important to identify possible systematic changes during establishment and passaging in mice. METHODS: High-resolution microarray-based comparative genomic hybridization (array CGH) was used to investigate how well a series of sarcoma xenografts, including 9 patient/xenograft pairs and 8 early versus late xenograft passage pairs, represented the patient tumor from which they originated. RESULTS: In all analyses, the xenografts were more similar to their tumor of origin than other xenografts of the same type. Most changes in aberration patterns were toward a more normal genome complement, and the increased aberrations observed were mostly toward more loss. In general, the changes were scattered over the genome, but some changes were significant in osteosarcomas. These were rather focused and consistent with amplifications frequent in patient samples, involving the genes platelet-derived growth factor receptor A (PDGFRA), cysteine-rich hydrophobic domain 2 (CHIC2), FIP-like 1 (FIP1L1), ligand of numb-protein X1 (LNX1), RAS-like family 11 member B (RASL11B), and sec1 family domain containing 2 (SCFD2), probably a sign of continued tumor progression. Some changes that disappeared may have been involved in host-stroma interactions or chemotherapy resistance, possibly because of the absence of selection in the mouse. CONCLUSIONS: Direct xenografts reflected well the genomic patterns of their tumors of origin. The few significant aberrations that were lost during passaging in immune-defective mice may have been caused by the lack of selection in the new host, whereas aberrations that were gained appeared to be the result of general tumor progression rather than model-specific artifacts. Cancer 2011;. © 2011 American Cancer Society.

Background: Superficial/cutaneous Ewing’s sarcoma family of tumors (ESFT) are rare and have a relatively favorable prognosis compared with deep-seated tumors. The aim of the present study is to describe the clinicopathological characteristics of six genetically confirmed ESFT presenting a superficial location. Methods: Clinical data, radiology, histopathology, immunohistochemistry, molecular study [reverse transcriptase-polymerase chain reaction (RT-PCR)/fluorescence in situ hybridization], treatment and follow-up data were retrieved. Results: Locations included fingers (2), back (1), neck (1), thigh (1) and subcutaneous breast (1). Two tumors showed conventional morphology, one consisted of primitive neuroectodermal tumor and three tumors showed atypical vascular morphology with hemosiderin deposition and pigmentation. All cases showed CD99, FLI-1, HNK-1 and CAV-1 positivity. RT-PCR revealed the EWS/Fli1 gene fusion in all cases. Treatment was by wide excision in all cases; one received chemotherapy (CT) and one CT and radiotherapy. Available follow-up revealed the following: two patients with metastasis and death at 5 months and 2 years and one local recurrence at 18 years. Conclusions: Superficial ESFT appears to have a relatively favorable prognosis but further studies with additional series, a larger number of cases and more extensive follow-up are necessary to confirm this statement.

Artículo publicado en: International Journal of Surgical Pathology published online 18 July 2010 The purpose of this study was to examine the immunoexpression of cell adhesion molecules (CAMs) E-cadherin, CD44s, and CD44v3 in cervical cancer and compare it with that in benign exo-endocervical tissue. In all, 81 cervical cancer biopsy specimens and 22 benign controls were included. Primary monoclonal antibodies NHC-38, F10-44-2, and 3G5 for E-cadherin, CD44s, and CD44v3 were used, respectively. Statistical significance was evaluated by the ?2 test. Antigen expression was significantly different in cervical cancer specimens compared with controls, showing marked decrease in membrane expression: E-cadherin, 6.5% and 77.3% (P < .000); CD44s, 3.9% and 81.8% (P < .000); and CD44v3, 0% and 81.8% (P < .000), respectively. The immunoexpression was significantly heterogeneous in carcinomas (P < .034) and adenocarcinomas (P < .000) for E-cadherin and CD44s. For CD44v3, no case of cancer showed immunostaining in membranes. These findings reaffirm that cell adhesion is markedly altered in cervical cancer. The authors suggest that these proteins could serve as markers for invasive cervical neoplasia. tmorelva@ula.ve antonio.llombart@uv.es

To compare the sensitivity and specificity of fluorescence in situ hybridization (FISH) with reverse transcription polymerase chain reaction (RT-PCR) in the diagnosis of Ewing sarcoma family of tumors (ESFTs) and other small round-cell tumors (SRCTs) in formalin-fixed paraffin-embedded tissue assembled in tissue microarrays (TMAs). The second objective is to confirm the value of molecular methods and immunohistochemical (IHC) assays, to perform a differential diagnosis between ESFTs and SRCTs with similar or overlapping morphology.A total of 560 cases were selected for the present study out the 806 cases collected from the PROgnosis and THerapeutic Targets in the Ewing's Family of TumorS project. Case selection bias included only the cases with enough material to enable the TMA construction, as FISH analysis and the majority of IHC studies were performed in TMAs. Histopathologic, IHC, and molecular assays were carried out.Of the 560 total cases, 411 (73.4%) were considered informative (with results by FISH and/or RT-PCR assays). From the informative cases, 382 (92.9%) were diagnosed as ESFT, 23 cases (5.6%) as non-ESFT but with specific diagnosis for another established entity, and 6 cases (1.5%) as small round cell tumors not otherwise specified. Sensitivity and specificity for the FISH assays was 96.3% and 95.2%, respectively, whereas RT-PCR presented a sensitivity of 97.5% and specificity of 92.9%. In concordant cases, both methods showed a sensitivity and specificity of 99.2% and 100%, respectively. Twenty-nine cases (7.1%) initially interpreted at morphologic level as atypical ESFTs were finally reclassified, with the support of molecular methods and IHC, as either non-ESFT with another specific histologic type or as small round cell tumors not otherwise specified.FISH and RT-PCR are ancillary techniques possessing high sensitivity in the diagnosis of ESFT; nevertheless, FISH is more specific than RT-PCR in the diagnosis of formalin-fixed paraffin-embedded tissue. Both methods in combination displayed the highest sensitivity and specificity. The combination of histopathologic, IHC, and molecular findings is the method of choice for the diagnosis of ESFT, as well as for the differential diagnosis with other SRCTs.

Ewing sarcoma is a highly aggressive malignant bone tumor occurring preferentially in children and young adults. At present, only clinical features, such as patient age, presence of clinically evident metastases at diagnosis, and poor response to neoadjuvant chemotherapy, are widely accepted as prognostic indicators in Ewing sarcoma. In this study, we assessed the prognostic value of CCN3 (Nov), a matricellular protein that play crucial roles in bone formation. Polyclonal antibodies directed against each of the different CCN3 modules were used to identify variant CCN3 proteins in tumors and to draw potential relationships between the expression of these variants and the outcome of patients with Ewing sarcoma. Our results confirmed that expression of the full-length CCN3 in Ewing sarcoma is associated to a worse prognostic. Furthermore, we report a possible relationship between the expression of a CCN3 protein lacking an internal module (von Willebrand factor type C) and sensitivity to radiotherapy. We hypothesize that the increased level of variant CCN3 in the tumor cells reduces their tumorigenic potential and results in better outcome.

Artículo publicado en: Virchows Arch (2009) 455:235–243. DOI 10.1007/s00428-009-0818-7 Ubiquitin and telomerase immunohistochemical expression patterns in cervical cancer were compared with normal cervical tissue samples. Eighty-one cervical cancer cases and 22 normal exo–endocervical tissue were examined with polyclonal antibody for ubiquitin and 44G12 clone for telomerase using tissue microarrays. The results were interpreted using a semiquantitative scale The average age of patients was 50.67 years. The most frequent histological types were moderately differentiated epidermoid carcinoma (43.5%), according to the degree of differentiation, and endocervical adenocarcinoma (42.1%). Immunohistochemical findings were as follows: 98.7% of cervical cancers showed immunoexpression for ubiquitin and 52.6% for telomerase. Statistically significant differences were found in tumor immunoreactivity when compared with control tissue (p

Inflammatory fibroid polyp (IFP) is a benign reactive uncommon submucosal lesion of the gastrointestinal tract, the small intestine being the most common site of origin. Histologically, IFPs are characterized by spindle cells, a heavy inflammatory infiltrate including eosinophils and onion-sheet-like formation of lesional cells around blood vessels. We present a case report of an IFP harboring an activation mutation in the PDGFR alpha gene. The lesion was positive for CD34, PDGFR alpha, and p-PDGFR alpha immunostaining but was negative for c-KIT and desmin. After a sequencing analysis of KIT and PDGFR alpha, a mutation consisting of an in-frame deletion of codons 567-571 and a missense mutation in codon 566 (S566R) of PDGFR alpha was observed. This mutation could activate key cellular pathways with involvement in the pathogenesis of this entity. We concluded that more studies are necessary in order to clarify if this finding is a biologically distinct behavior or, on the contrary, represents a specific feature of the IFP.

Background Neuroblastic tumors (NT) are pediatric neoplasms with a heterogeneous genetic profile. They present genotypic alterations of prognostic value, the study of which is mandatory in designing therapeutic management. Tissue microarrays (TMA) from paraffin material allow the analysis of a large number of cases with minimal costs. The main purpose of the present study is to analyze specific genetic markers of neuroblastic tumors included in TMAs and determine their prognostic value. We compare the results obtained by different molecular techniques at different substrates to evaluate the feasibility of these assays. Procedure One hundred thirty-nine samples were included in four different TMAs. We performed FISH assays to determine the status of MYCN gene, 1p36 region and 17q23 arm. The prognostic value of the genetic markers as well as the statistical correlation among clinical variables and outcome were analyzed by SPSS. Results MYCN amplification was detected in 35.3% of the cases, whereas 1p36 deletion and 17q23 gain was observed in 46.8% and 58.3% of the cases, respectively. An adverse prognosis was noted among these patients. Other adverse factors were age (>18 months) as well as high stage of disease (stage 4). Phenotypic signs of differentiation correlated with good outcome. Conclusion Retrospective studies using paraffin-embedded tissues assembled in TMA are a useful tool for the analysis of prognostic factors in NT. Pediatr Blood Cancer 2009;52:209–214. © 2008 Wiley-Liss, Inc.

We report two cases of malignant peripheral nerve sheath tumor (MPNST) in an uncommon location (heart and retropharynx) both with divergent osseous heterologous differentiation. We present the pathological and immunohistochemical studies that confirmed the neurogenic origin. The histopathology of the tumor arising in the retropharynx showed a transition from a neurofibroma to MPNST, making this a new report of an MPNST arising from a plexiform neurofibroma without neurofibromatosis. Primary cardiac MPNST with osseous differentiation has never been reported before. In conclusion, the histology of MPNSTs is very heterogeneous, showing no specific diagnostic immunoprofile or genetic alteration. Thus, it is important to rule out other histologically similar tumors, particularly in cases arising in uncommon locations or tumors with divergent heterologous differentiation.

We aimed to detect truncated CCN3 protein variants in formalin-fixed paraffin-embedded samples of eight Wilms' tumors using anti-K19M and novel domain-specific antibodies, anti-NH2, anti-NH3, anti-NH4, and anti-NH5 raised against C-terminal (CT) domain and modules 1, 2, 3, and 4 of the CCN3 protein, respectively. In Wilms' tumors, all the domain antibodies except anti-NH4 exhibited both nuclear and cytoplasmic staining in blastema as well as primitive tubules. NH4 was detected only in the cytoplasm of tumor cells. Normal fetal kidneys revealed mainly cytoplasmic immunoreactivity for all antibodies in tubules and glomeruli, except for K19 and NH5, which showed some nuclear staining. Our data suggest expression of a truncated nuclear CCN3 variant lacking the thrombospondin type-1-like domain and cytoplasmic full-length CCN3 protein in Wilms' tumor cells. In addition, normal fetal kidneys express mainly full-length protein mostly localized to cytoplasm. Truncated CCN3 protein in Wilms' tumor cells may provide evidence for its tumorigenic role in these tumors. Uniform NH5 staining compared to variable expression of K19M indicates that using NH5 is a better approach for detecting the CT domain of CCN3 protein in archival specimens. Thus, the domain-specific antibodies represent valuable tools for detecting CCN3 protein variants in normal and neoplastic kidneys.

The clinical evolution and biology of granular cell tumors (GCT) are poorly understood and treatment remains an issue of discussion. The majority of GCT are benign, although some display malignant behavior. The distinction between benign, atypical, and malignant GCT is controversial due to morphological and immunohistochemical overlap and lack of consistent histological and phenotypic criteria that predict behavior. Although histological criteria may indicate increased risk of malignant evolution, some GCT with evident benign appearance exceptionally progress towards metastatic disease. In this review, we discuss current knowledge on GCT, including histologic, immunophenotypic, and molecular characteristics and differential diagnosis. We focus on the following problematic items in GCT: (1) evolution of classification, (2) neural versus non-neural GCT, (3) neoplastic versus reactive disease, (4) malignant transformation of benign GCT, and (5) multiple versus metastatic GCT. We conclude that although a Ki-67 index >10 % and the presence of mitoses and/or of necrosis are frequently associated with malignant behavior, metastasis remains the only unequivocal sign of malignancy in GCT. An infiltrative growth pattern and vascular and/or perineural invasion are not indicative of malignancy. GCT with atypical/uncertain features almost never metastasize, and many of these tumors either behave in a benign fashion or only recur locally (similar to incompletely excised benign tumors). We therefore propose that classical and atypical histological variants form a single group of GCT. GCT with various unfavorable histological features might be labeled as “GCT with increased risk of metastasis” rather than malignant GCT.

Sarcoma with CIC-DUX4 gene fusion is emerging as the most prevalent subset of Ewing-like undifferentiated small round cell sarcomas with around 50 cases published. We report hereby the case of a 40-year-old male who presented a CIC-DUX4 sarcoma in deep soft tissues in his thigh. He had been diagnosed with neurofibromatosis type 1 at age 19 and over the years underwent resection of multiple neural neoplasms, including two malignant peripheral nerve sheath tumors with classical spindle-cell histopathology. The CIC-DUX4 sarcoma was treated with surgical resection, radiation and chemotherapy, but lung and brain metastases developed and the patient died from the disease 14 months after diagnosis. This is the first case of sarcoma with CIC-DUX4 gene fusion reported in a patient with NF1. Whether this association is coincidental or CIC-DUX4 sarcomas could be related to NF1 remains to be clarified. Study of alternative molecular alterations in EWSR1-negative undifferentiated small round cell sarcomas is clinically relevant, since CIC-DUX4 sarcomas seem to be a very aggressive subset with poor response to the presently used therapeutic regimens.

Osteosarcoma (Os) is the most common malignant bone tumor in childhood and not rare in adults. In recent years, much research has focused on the role of angiogenesis in tumor development, growth, invasion, and metastasis. The aims of this study were to characterize neovascularization established between the xenotransplanted Os and the host at histological, immunohistochemical, ultrastructural, and molecular level, and to evaluate if this model could be used in testing new anti-angiogenic drugs. Three xenotransplanted human Os were evaluated. Tumor pieces 3–4 mm in size were implanted subcutaneously on the back of athymic Balb-c nude mice (n = 14). The animals were killed at 24, 48, and 72 h and 7, 14, 21, and 28 days after implantation. Tumor samples were either fixed in 10 % formaldehyde and embedded in paraffin for histological analysis, or fixed with glutaraldehyde (2 %) for electron microscopy or retained non-fixed for molecular analysis (ELISA and qRT-PCR). Morphologically, intense neo-vasculogenesis within tumor parenchyma was present between the first and third week after transplantation. Immunohistochemistry demonstrated overexpression of VEGF and their receptors together with PDFGFRA 24–48 h after tumor implantation. Additionally, neoplastic cells co-expressed chemokines (CXCL9, CXCL10, and GRO) and their receptors. Molecular studies showed two expression profiles, distinguishing an early and a late phase in the angiogenic process. In Os, our model showed two stages of induced angiogenesis, with close association between histological and molecular events. This approximation could be of use for testing the effect of different anti-angiogenic agents.

This paper discusses the diversity of synovial sarcomas (SSs) [biphasic (BSS), monophasic fibrous (MFSS), and poorly differentiated (PDSS)] and tissue microarray (TMA) evaluation of the immunophenotypic and histological progression of SSs in nude mice using three TMAs comprising 11 primary SSs (8 MFSSs, 2 BSSs, and 1 PDSS) and their xenografts. BSS and MFSS progressively transformed to a similar undifferentiated phenotype with loss of glandular component in the xenografts. Epidermal growth factor receptor and SALL2 were expressed in primary tumors and xenografts. Enhanced bcl-2 and bax expression were noted in xenografts. Ki-67 overexpression in xenografts correlated with high mitotic index. Epithelial membrane antigen (EMA) and cytokeratin AE1/AE3 were detected in all original and xenografted SSs. Hierarchical clustering differentiated original MFSS and BSS, but their xenografts clustered together due to similar immunoexpression profile. Our study demonstrates definite phenotypic variability of BSS and MFSS in the xenografts. Differences in immunoexpression for various markers existed between primary tumor and xenografts but not between subtypes. Hierarchical clustering grouped TMA immunostaining data and confirmed immunophenotypic variability; however, it failed to reveal any immunophenotypic differences between SYT-SSX1 and SYT-SSX2 type tumors. Nonetheless, reverse-transcriptase-polymerase chain reaction detected SYT-SSX transcripts in all primary SSs and their xenografts, thereby demonstrating their genetic stability.

In less than half a decade, gastrointestinal stromal tumors (GIST) have emerged from historical anonymity to become a model of kinase-targeted therapies. Approximately 80% to 85% of GISTs harbor activating mutations of the KIT or PDGFRA tyrosine kinase genes, and such mutations have predictive and prognostic value. In this regard, the in vitro and in vivo models have provided valuable tools for understanding the molecular pathology of this interesting neoplasm. This review charts particular aspects in the field of cell cultures and tumor xenografts in nude mice in GIST and their implication in the establishment of appropriate models for discovering and testing therapy. The cytogenetic features of these tumors are also discussed. Classic karyotyping, loss of heterozygosity, fluorescent in situ hybridization, comparative genomic hybridization (CGH), and CGH-array analyses have shown that chromosomal numerical abnormalities and loss of genetic material at chromosomes 1p, 9p, 14q, and 22q are significantly associated with GIST malignancy and response to treatment. Furthermore, these regions constitute "hot" areas for finding candidate genes involved in the pathogenesis of GISTs. A deeper knowledge of these genetic aspects of GIST will provide a better understanding of this neoplasm that could translate into clinical practice.