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Sinonasal mucosal melanoma is a rare tumor arising within the nasal cavity, paranasal sinuses, or nasopharynx (sinonasal tract). This study evaluated 90 cases diagnosed in 29 males and 61 females with median age 68 years. Most tumors involved the nasal cavity and had an epithelioid morphology. Spectrum of research techniques used in this analysis includes targeted-DNA and -RNA next-generation sequencing, Sanger sequencing, fluorescence in situ hybridization and immunohistochemistry. Sinonasal melanomas were commonly driven by RAS (38/90, 42%), especially NRAS (n = 36) mutations and rarely (4/90, 4%) displayed BRAF pathogenic variants. BRAF/RAS mutants were more frequent among paranasal sinuses (10/14, 71%) than nasal (26/64, 41%) tumors. BRAF/RAS-wild type tumors occasionally harbored alterations of the key components and regulators of Ras-MAPK signaling pathway: NF1 mutations (1/17, 6%) or NF1 locus deletions (1/25, 4%), SPRED1 (3/25, 12%), PIK3CA (3/50, 6%), PTEN (4/50, 8%) and mTOR (1/50, 2%) mutations. These mutations often occurred in a mutually exclusive manner. In several tumors some of which were NRAS mutants, TP53 was deleted (6/48, 13%) and/or mutated (5/90, 6%). Variable nuclear accumulation of TP53, mirrored by elevated nuclear MDM2 expression was seen in50% of cases. Furthermore, sinonasal melanomas (n = 7) including RAS/BRAF-wild type tumors (n = 5) harbored alterations of the key components and regulators of canonical WNT-pathway: APC (4/90, 4%), CTNNB1 (3/90, 3%) and AMER1 (1/90, 1%). Both, TERT promoter mutations (5/53, 9%) and fusions (2/40, 5%) were identified. The latter occurred in BRAF/RAS-wild type tumors. No oncogenic fusion gene transcripts previously reported in cutaneous melanomas were detected. Eight tumors including 7 BRAF/RAS-wild type cases expressed ADCK4::NUMBL cis-fusion transcripts. In summary, this study documented mutational activation of NRAS and other key components and regulators of Ras-MAPK signaling pathway such as SPRED1 in a majority of sinonasal melanomas.

Preferentially expressed antigen in melanoma (PRAME) is considered a useful marker in the differential diagnosis between malignant melanoma and its melanocytic mimics. Recently PRAME expression was documented in nonmelanocytic tumors, but much of the data are based on mRNA studies. This investigation evaluated PRAME expression in the spectrum of normal tissues and5800 human tumors using immunohistochemistry and EP461 monoclonal antibody. In normal tissues, PRAME was expressed in the testis and proliferative endometrium. In tumors, PRAME was variably expressed in malignancies of different lineages. Among epithelial tumors,50% of PRAME-positive lesions were found among endometrial carcinomas (82%), uterine serous carcinomas (82%), uterine carcinosarcomas (60%), ovarian clear cell carcinomas (90%), ovarian serous carcinomas (63%), adenoid cystic carcinomas (81%), seminomas (78%), thymic carcinomas (75%), and basal cell carcinomas (62%). In mesenchymal and neuroectodermal malignancies, PRAME was frequently expressed in synovial sarcoma (71%), myxoid liposarcoma (76%), neuroblastoma (61%) and metastatic melanoma (87%). Also, PRAME was consistently expressed in 4 melanomas that lacked all melanoma markers including S100 protein and SOX10 but harbored typical for melanoma BRAF or NRAS driver mutations. However, strong and diffuse PRAME immunoreactivity was seen in many types of nonmelanocytic poorly differentiated carcinomas and sarcomas. Based on this study, PRAME is a relatively unspecific immunohistochemical marker, which limits its use in diagnostic surgical pathology. However, immunohistochemistry is a reliable and unexpensive method useful in detecting PRAME-positive malignancies for potential immunotherapy.

Mesothelin targeting CAR T cells have limited activity in patients. In this study, we sought to determine if efficacy of anti-mesothelin CAR T cells is dependent on the mesothelin epitopes that are recognized by them. To do so, we developed hYP218 (against membrane-proximal epitope) and SS1 (against membrane-distal epitope) CAR T cells. Their efficacy was assessed in vitro using mesothelin-positive tumor cell lines and in vivo in NSG mice with mesothelin-expressing ovarian cancer (OVCAR-8), pancreatic cancer (KLM-1), and mesothelioma patient-derived (NCI-Meso63) tumor xenografts. Persistence and tumor infiltration of CAR T cells was determined using flow cytometry. hYP218 CAR T cells killed cancer cells more efficiently than SS1 CAR T cells, with a two- to fourfold lower ET50 value (effector-to-target ratio for 50% killing of tumor cells). In mice with established tumors, single intravenous administration of hYP218 CAR T cells lead to improved tumor response and survival compared with SS1 CAR T cells, with complete regression of OVCAR-8 and NCI-Meso63 tumors. Compared with SS1 CAR T cells, there was increased peripheral blood expansion, persistence, and tumor infiltration of hYP218 CAR T cells in the KLM-1 tumor model. Persistence of hYP218 CAR T cells in treated mice led to antitumor immunity when rechallenged with KLM-1 tumor cells. Our results show that hYP218 CAR T cells, targeting mesothelin epitope close to cell membrane, are very effective against mesothelin-positive tumors and are associated with increased persistence and tumor infiltration. These results support its clinical development to treat patients with mesothelin-expressing cancers.

BACKGROUND: Germline inactivating variants in the CDH1 tumor suppressor gene impart an elevated lifetime risk of diffuse gastric cancer. The current endoscopic surveillance method depends upon random gastric biopsies for early cancer detection. METHODS: Asymptomatic adults with pathogenic or likely pathogenic CDH1 variants referred for endoscopic gastric cancer surveillance were included in this retrospective cohort. Upper gastrointestinal endoscopy was performed according to the consensus Cambridge method, in the early period, or a systematic (Bethesda) protocol as part of an ongoing natural history study. The primary outcome measure was cancer detection. RESULTS: Collectively, 135 endoscopic surveillance procedures were performed in 120 patients. Twenty-six (19%, 26/135) procedures were performed using Cambridge method and 109 (81%) using the Bethesda protocol. Gastric signet ring cell carcinomas were detected in 15% (4/26) using the Cambridge method and 36% (40/109) using the Bethesda protocol (p

Background Plexiform fibromyxoma (PF) is a rare gastric tumor often confused with gastrointestinal stromal tumor. These so-called “benign” tumors often present with upper GI bleeding and gastric outlet obstruction. It was recently demonstrated that approximately one-third of PF have activation of the GLI1 oncogene, a transcription factor in the hedgehog (Hh) pathway, via a MALAT1-GLI1 fusion protein or GLI1 up-regulation. Despite this discovery, the biology of most PFs remains unknown. Methods Next generation sequencing (NGS) was performed on formalin-fixed paraffin-embedded (FFPE) samples of PF specimens collected from three institutions (UCSD, NCI and OHSU). Fresh frozen tissue from one tumor was utilized for in vitro assays, including quantitative RT-PCR and cell viability assays following drug treatment. Results Eight patients with PF were identified and 5 patients’ tumors were analyzed by NGS. An index case had a mono-allelic PTCH1 deletion of exons 15–24 and a second case, identified in a validation cohort, also had a PTCH1 gene loss associated with a suspected long-range chromosome 9 deletion. Building on the role of Hh signaling in PF, PTCH1, a tumor suppressor protein, functions upstream of GLI1. Loss of PTCH1 induces GLI1 activation and downstream gene transcription. Utilizing fresh tissue from the index PF case, RT-qPCR analysis demonstrated expression of Hh pathway components, SMO and GLI1, as well as GLI1 transcriptional targets, CCND1 and HHIP. In turn, short-term in vitro treatment with a Hh pathway inhibitor, sonidegib, resulted in dose-dependent cell killing. Conclusions For the first time, we report a novel association between PTCH1 inactivation and the development of plexiform fibromyxoma. Hh pathway inhibition with SMO antagonists may represent a target to study for treating a subset of plexiform fibromyxomas. Electronic supplementary material The online version of this article (10.1186/s12967-019-1995-z) contains supplementary material, which is available to authorized users.

Poorly differentiated neoplasms lacking characteristic histopathologic features represent a significant challenge to the pathologist for diagnostic classification. Classically, NUT carcinoma (previously NUT midline carcinoma) is poorly differentiated but typically exhibits variable degrees of squamous differentiation. Diagnosis is genetically defined by NUTM1 rearrangement, usually with BRD4 as the fusion partner. In this multi-institutional next-generation sequencing and fluorescence in situ hybridization study, 26 new NUTM1-rearranged neoplasms are reported, including 20 NUT carcinomas, 4 sarcomas, and 2 tumors of an uncertain lineage. NUTM1 fusion partners were available in 24 of 26 cases. BRD4 was the fusion partner in 18/24 (75%) cases, NSD3 in 2/24 cases (8.3%), and BRD3 in 1/24 (4.2%) cases. Two novel fusion partners were identified: MGA in two sarcomas (myxoid spindle cell sarcoma and undifferentiated sarcoma) (2/24 cases 8.3%) and MXD4 in a round cell sarcoma in the cecum (1/24 cases 4.2%). Eleven cases tested for NUT immunoexpression were all positive, including the MGA and MXD4-rearranged tumors. Our results confirm that NUTM1 gene rearrangements are found outside the classic clinicopathological setting of NUT carcinoma. In addition, as novel fusion partners like MGA and MXD4 may not be susceptible to targeted therapy with bromodomain inhibitors, detecting the NUTM1 rearrangement may not be enough, and identifying the specific fusion partner may become necessary. Studies to elucidate the mechanism of tumorigenesis of novel fusion partners are needed.

Objectives Arterial calcification due to deficiency of CD73 (ACDC) is a hereditary autosomal recessive ectopic mineralization syndrome caused by loss-of-function mutations in the ecto-5′-nucleotidase gene. Periarticular calcification has been reported but the clinical characterization of arthritis as well as the microstructure and chemical composition of periarticular calcifications and SF crystals has not been systematically investigated. Methods Eight ACDC patients underwent extensive rheumatological and radiological evaluation over a period of 11 years. Periarticular and synovial biopsies were obtained from four patients. Characterization of crystal composition was evaluated by compensated polarized light microscopy, Alizarin Red staining for synovial fluid along with X-ray diffraction and X-ray micro tomosynthesis scanner for periarticular calcification. Results Arthritis in ACDC patients has a clinical presentation of mixed erosive-degenerative joint changes with a median onset of articular symptoms at 17 years of age and progresses over time to the development of fixed deformities and functional limitations of small peripheral joints with, eventually, larger joint and distinct axial involvement later in life. We have identified calcium pyrophosphate and calcium hydroxyapatite (CHA) crystals in SF specimens and determined that CHA crystals are the principal component of periarticular calcifications. Conclusion This is the largest study in ACDC patients to describe erosive peripheral arthropathy and axial enthesopathic calcifications over a period of 11 years and the first to identify the composition of periarticular calcifications and SF crystals. ACDC should be considered among the genetic causes of early-onset OA, as musculoskeletal disease signs may often precede vascular symptoms.

Metastatic Leydig cell tumors (LCT) are rare, difficult-to-treat malignancies without known underlying molecular-genetic events. An index case of metastatic LCT showed an LDLR-TERT gene fusion upon routine genetic profiling for detection of therapeutic targets, which was then followed by an investigation into a cohort of additional LCTs.Twenty-nine LCT (27 male and 2 female patients) were profiled using next-generation sequencing and immunohistochemistry.TERT gene fusions were detected only in testicular metastatic LCTs, in 3 of 7 successfully analyzed cases (RMST:TERT, LDLR:TERT, and B4GALT5:TERT). TOP1 and CCND3 amplifications were identified in the case with a B4GALT5:TERT fusion. A TP53 mutation was detected in 1 metastatic tumor without a TERT fusion. Five primary (4 testicular and 1 ovarian) LCTs showed multiple gene amplifications, without a consistent pattern. A single metastatic ovarian LCT showed BAP1 mutation and copy number amplifications affecting the NPM1, PCM1, and SS18 genes. At the protein level, 4 of 7 metastatic and 6 of 10 primary testicular LCTs overexpressed Topo1. Androgen receptor was overexpressed in 10 of 13 primary testicular tumors and 2 of 5 metastatic testicular LCTs (without detectable ARv7 messenger RNA or ARv7 protein). Only 1 metastatic testicular LCT exhibited a high tumor mutational burden; all tested cases were microsatellite instability stable and did not express programmed cell death ligand 1.Our study for the first time identified TERT gene fusions as a main genetic alteration and a potential therapeutic target in metastatic LCTs. Topo1 and androgen receptor may guide decisions on chemotherapy and/or hormone therapy for selected individual patients.

Background : Adrenocortical carcinoma (ACC) is a rare malignancy arising from the adrenal cortex. ACC carries a dismal prognosis and surgery offers the only chance for a cure. Germline pathogenic variants among certain oncogenes have been implicated in ACC. Here, we report the first case of ACC in a patient with a pathogenic variant in the Ataxia Telangiectasia Mutated (ATM) gene. Patients and Methods : A 56-year-old Caucasian woman with biopsy proven ACC deemed unresectable and treated with etoposide, doxorubicin and cisplatin (EDP), and mitotane presented to our institution for evaluation. The tumor specimen was examined pathologically, and genetic analyses were performed on the tumor and germline using next-generation sequencing. Results : Pathologic evaluation revealed an 18.0 × 14.0 × 9.0 cm low-grade ACC with tumor free resection margins. Immunohistochemistry stained for inhibin, melan-A, and chromogranin. ClinOmics analysis revealed a germline pathogenic deletion mutation of one nucleotide in ATM is denoted as c.1215delT at the cDNA level and p.Asn405LysfsX15 (N405KfsX15) at the protein level. Genomic analysis of the tumor showed loss of heterozygosity (LOH) of chromosome 11 on which the ATM resides. Conclusion : ACC is an aggressive malignancy for which surgical resection currently offers the only curative option. Here we report a heterozygous loss-of-function mutation in germline DNA and LOH of ATM in tumor in an ACC patient, a classic two-hit scenario in a well-known cancer suppresser gene, suggesting a pathogenic role of the ATM gene in certain ACC cases.

DICER1 syndrome is a rare pediatric autosomal dominant inherited disorder predisposing to various benign and malignant tumors. It is caused by a germline pathogenic variant in DICER1 and the second hit for tumor development is usually a missense hotspot pathogenic variant in the DICER1 ribonuclease IIIb domain. While DICER1 predisposing variants account for about 60% of ovarian Sertoli-Leydig cell tumors, no DICER1-related testicular stromal tumors have been described. Here we report the first two cases of testicular stromal tumors in children carrying a DICER1 germline pathogenic variant: a case of Sertoli cell tumor and a case of Leydig cell tumor diagnosed at 2 and 12 years of age, respectively. A somatic DICER1 hotspot pathogenic variant was detected in the Sertoli cell tumor. This report extends the spectrum of DICER1-related tumors to include testicular Sertoli cell tumor and potentially testicular Leydig cell tumor. Diagnosis of a testicular Sertoli cell tumor should prompt DICER1 genetic testing so that patients with a DICER1 germline pathogenic variant can benefit from established surveillance guidelines. DICER1 genetic evaluation may be considered for testicular Leydig cell tumor. Our findings suggest that miRNA dysregulation underlies the etiology of some testicular stromal tumors.

This study determined the frequency and the clinicopathologic and genetic features of colorectal carcinomas driven by oncogenic fusions of the anaplastic lymphoma kinase gene (ALK). Of the 8150 screened tumors, 12 (0.15%) were immunohistochemically ALK-positive with D5F3 antibody. These cancers harbored CAD-ALK (n=1), DIAPH2-ALK (n=2), EML4-ALK (n=2), LOC101929227-ALK (n=1), SLMAP-ALK (n=1), SPTBN1-ALK (n=4), and STRN-ALK (n=1) fusions, as detected by an RNA-based next-generation sequencing assay. ALK fusion carcinomas were diagnosed mostly in older patients with a 9:3 female predominance (median age: 72 y). All tumors, except a rectal one, occurred in the right colon. Most tumors were stage T3 (n=7) or T4 (n=3). Local lymph node and distant metastases were seen at presentation in 9 and 2 patients. These tumors showed moderate (n=6) or poor (n=3) glandular differentiation, solid medullary growth pattern (n=2), and pure mucinous morphology (n=1). DNA mismatch repair-deficient phenotype was identified in 10 cases. Tumor-infiltrating lymphocytes were prominent in 9 carcinomas. In 4 carcinomas, tumor cells showed strong, focal (n=3), or diffuse programmed death-ligand 1 immunoreactivity. CDX2 expression and loss of CK20 and MUC2 expression were frequent. CK7 was expressed in 5 tumors. Four patients died of disease within 3 years, and 7 were alive with follow-up ranging from 1 to 8 years. No mutations in BRAF, RAS, and in genes encoding components of PI3K-AKT/MTOR pathway were identified. However, 1 tumor had a loss-of-function PTEN mutation. Aberration of p53 signaling, TP53 mutations, and/or nuclear accumulation of p53 protein was seen in 9 cases. ALK fusion colorectal carcinomas are a distinct and rare subtype of colorectal cancers displaying some features of mismatch repair-deficient tumors.

Distinction of paraganglioma (PGL) from epithelial neuroendocrine tumors (NETs) can be difficult as they can mimic each other by nested architecture and expression of neuroendocrine markers. In this study, we examined differential diagnostic markers in 262 PGLs (142 adrenal pheochromocytomas and 120 extra-adrenal PGLs), 9 duodenal gangliocytic PGLs and 3 cauda equina PGLs, and 286 NETs (81 GI, 78 pancreatic, 42 thoracic, 37 medullary thyroid carcinomas, and 48 high-grade NETs including 32 small cell carcinomas of lung). While keratin expression was nearly uniform in NETs with the exception of few tumors, extensive keratin expression was seen in only one PGL (1%) and focal expression in 5% PGLs. GATA3 was present in90% of PGLs but only in 2% of NETs, usually focally. Tyrosine hydroxylase (TH) was expressed in90% of adrenal, abdominal, and thoracic PGLs but only in 37% of head and neck PGLs, reflecting their variable catecholamine synthesis. Focal or occasional extensive TH-expression was detected in 10% of NETs. CDX2 was a helpful discriminator seen in 28% of pancreatic and most GI NETs but in no PGLs. SOX10 detected sustentacular cells in 85% of PGLs and 7% of NETs, whereas GFAP detected sustentacular cells mainly in PGLs of neck and was absent in NETs. Duodenal gangliocytic PGLs (n = 9) and all cauda equina PGLs (n = 3) expressed keratins, lacked GATA3, showed no or minimal TH expression as some NETs, and contained SOX10 and S100 protein-positive spindle cells negative for GFAP. Ganglion-like epithelioid cells were keratin-positive and negative for TH and SOX10 differing from true ganglion cells. We conclude that duodenal gangliocytic and cauda equina PGLs have a NET-like immunoprofile and differ from ordinary PGLs. NETs can be distinguished from PGLs by their expression of keratins and general lack of GATA3, TH, and GFAP-positive sustentacular cells, and sometimes by expression of CDX2 or TTF1.

This study determined the frequency and the clinicopathologic and genetic features of colorectal carcinomas driven by oncogenic fusions of the anaplastic lymphoma kinase gene (ALK). Of the 8150 screened tumors, 12 (0.15%) were immunohistochemically ALK-positive with D5F3 antibody. These cancers harbored CAD-ALK (n=1), DIAPH2-ALK (n=2), EML4-ALK (n=2), LOC101929227-ALK (n=1), SLMAP-ALK (n=1), SPTBN1-ALK (n=4), and STRN-ALK (n=1) fusions, as detected by an RNA-based next-generation sequencing assay. ALK fusion carcinomas were diagnosed mostly in older patients with a 9:3 female predominance (median age: 72 y). All tumors, except a rectal one, occurred in the right colon. Most tumors were stage T3 (n=7) or T4 (n=3). Local lymph node and distant metastases were seen at presentation in 9 and 2 patients. These tumors showed moderate (n=6) or poor (n=3) glandular differentiation, solid medullary growth pattern (n=2), and pure mucinous morphology (n=1). DNA mismatch repair-deficient phenotype was identified in 10 cases. Tumor-infiltrating lymphocytes were prominent in 9 carcinomas. In 4 carcinomas, tumor cells showed strong, focal (n=3), or diffuse programmed death-ligand 1 immunoreactivity. CDX2 expression and loss of CK20 and MUC2 expression were frequent. CK7 was expressed in 5 tumors. Four patients died of disease within 3 years, and 7 were alive with follow-up ranging from 1 to 8 years. No mutations in BRAF, RAS, and in genes encoding components of PI3K-AKT/MTOR pathway were identified. However, 1 tumor had a loss-of-function PTEN mutation. Aberration of p53 signaling, TP53 mutations, and/or nuclear accumulation of p53 protein was seen in 9 cases. ALK fusion colorectal carcinomas are a distinct and rare subtype of colorectal cancers displaying some features of mismatch repair-deficient tumors.

Background Neurofibromatosis 1 (NF1) leads to the development of benign and malignant peripheral nerve sheath tumors (MPNST). MPNST have been described to develop in preexisting benign plexiform neurofibromas (PN) and have a poor prognosis. Atypical neurofibromas (ANF) were recently described as precursor lesions for MPNST, making early detection and management of ANF a possible strategy to prevent MPNST. We aimed to clinically characterize ANF and identify management approaches. Methods We analyzed clinical, imaging, and pathology findings of all patients with NF1 and ANF at 3 institutions. Results Sixty-three patients had 76 ANF (32M/31F; median age 27.1 y). On MRI, most ANF appeared as distinct nodular lesions and were 18F-fluorodeoxyglucose (FDG) avid. Forty-six ANF were associated with pain, 19 with motor weakness, 45 were palpable or visible, and 13 had no clinical signs. Completely resected ANF (N = 57) have not recurred (median follow-up, 4.1 y; range, 0-14 y). Four ANF transformed into MPNST and 17 patients had a history of MPNST in a different location than was their ANF. Conclusions Growth of distinct nodular lesions, pain, and FDG-PET avidity should raise concern for ANF in NF1. Patients with ANF are at greater risk for development of MPNST. Complete resection of ANF may prevent development of MPNST.

Context No effective methods for separating primary pheochromocytomas and paragangliomas with metastatic potential are currently available. The identification of specific asparagine-linked glycan (N-glycan) structures, which are associated with metastasized pheochromocytomas and paragangliomas, may serve as a diagnostic tool. Objective To identify differences in N-glycomic profiles of primary metastasized and nonmetastasized pheochromocytomas and paragangliomas. Setting This study was conducted at Helsinki University Hospital, University of Helsinki, and Glykos Finland Ltd. and included 16 pheochromocytomas and paragangliomas: 8 primary metastasized pheochromocytomas or paragangliomas and 8 nonmetastasized tumors. Methods N-glycan structures were analyzed with matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) profiling of formalin-fixed, paraffin-embedded tissue samples. Main outcome measure N-glycan profile of tumor tissue. Results Four groups of neutral N-glycan signals were more abundant in metastasized tumors than in nonmetastasized tumors: complex-type N-glycan signals of cancer-associated terminal N-acetylglucosamine, multifucosylated glycans (complex fucosylation), hybrid-type N-glycans, and fucosylated pauci-mannose-type N-glycans. Three groups of acidic N-glycans were more abundant in metastasized tumors: multifucosylated glycans, acid ester-modified (sulfated or phosphorylated) glycans, and hybrid-type/monoantennary N-glycans. Fucosylation and complex fucosylation were significantly more abundant in metastasized paragangliomas and pheochromocytomas than in nonmetastasized tumors for individual tests but were over the false positivity critical rate, when adjusted for multiplicity testing. Conclusions MALDI-TOF MS profiling of primary pheochromocytomas and paragangliomas can identify diseases with metastatic potential based on their different N-glycan profiles. Thus, malignancy-linked N-glycan structures may serve as potential diagnostic tools for pheochromocytomas and paragangliomas.

Most gastrointestinal stromal tumors (GISTs) occur in the tubular gastrointestinal (GI) tract, but some present apparently outside the GI tract. In this study, we analyzed 112 GISTs located in the retroperitoneum. These tumors occurred in 55 women and 57 men with a median age of 65 years (range: 21 to 89 y). On the basis of clinically or histologically detected connections to GI tract, 15 tumors were considered likely of gastric, 9 duodenal, and 13 of small intestinal origin. The remaining cases were categorized by location as peripancreatic (n=25), pelvic (n=11), mesenteric (n=4), and of unspecified/miscellaneous sites (n=35). The tumors varied in size 3 to 35 cm (median, 15 cm) and by mitotic rate per 5 mm, 0 to100 (median, 10). Histologically the tumors apparently arising outside the GI tract had features of intestinal (n=41) and gastric GISTs (n=25); 9 cases had indeterminate histology. The histologic variants included spindled, epithelioid, vacuolated, nested, and myxoid potentially simulating other tumors such as liposarcoma and solitary fibrous tumor. Most GISTs were KIT-positive (106/112 cases), and the remaining 6 tumors were DOG1/Ano1-positive. Five cases showed focal nuclear positivity for MDM2. KIT mutations were detected in 42/59 cases, and PDGFRA mutations in 4/16 KIT wild-type and 3/5 of the KIT-negative tumors analyzed. One pelvic retroperitoneal GIST was succinate dehydrogenase deficient. All 79 patients were dead at last follow-up with a median survival of 14 months, with few survivals5 years. Only operable versus inoperable tumor was a statistically favorable factor in univariate analysis (P0.01). In multivariate analysis, mitotic rate50/5 mm was significant for a shorter survival (hazard ratio, 5.25; 95% confidence interval, 1.65-16.8; P0.01). Histologic and clinicopathologic similarity of extragastrointestinal retroperitoneal GISTs with GISTs of GI tract suggests their GI tract origin. Potentially overlapping features between GIST and other retroperitoneal tumors necessitate use of multiple diagnostic markers and molecular genetic studies.

Loss-of-function germline mutations in the fumarase (FH) gene of the Krebs cycle characterize hereditary leiomyomatosis and renal cell cancer syndrome. Fumarase (FH) deficiency can be diagnosed by the loss of immunohistochemical expression. In this study, we investigated the occurrence and clinicopathologic features of FH-deficient uterine smooth muscle tumors (SMTs). A total of 1583 uterine and 157 nonuterine SMTs were examined using a polyclonal FH antibody and automated immunohistochemistry, and 86 uterine leiomyomas with an FH loss were identified. The frequencies of FH deficiency for subcohorts of uterine SMTs were 1.6% for unselected nonatypical leiomyomas, 1.8% for cellular leiomyomas, 37.3% for atypical leiomyomas, and 0% for leiomyosarcomas. One extrauterine, retroperitoneal estrogen receptor-positive leiomyoma was also FH deficient. The patient age of FH-deficient uterine leiomyomas was 20 to 52 years (median, 38 y). Grossly, these tumors were often soft and amorphous resembling a fibrothecoma. Histologically, the FH-deficient nonatypical leiomyomas lacked cellular packeting and distinct collagenous zones and showed chain-like or palisading nuclear arrangements, prominent staghorn-shaped blood vessels, oval nuclei with no or at most mild atypia, small eosinophilic nucleoli, and a low mitotic rate (0 to 1/10 HPF). The FH-deficient atypical leiomyomas had nuclear atypia often manifesting as multinucleation, prominent eosinophilic nucleoli, and mitotic activity up to 7/10 HPF, with atypical mitoses seen in 32% of cases. However, similar histologic changes were seen in some non-FH-deficient atypical leiomyomas. Loss-of-function FH-gene mutations including 5 whole-gene deletions and 3 frameshift mutations were identified in 8 of 16 FH-deficient nonatypical leiomyomas using multiplex ligation-dependent probe amplification and Sanger sequencing, respectively. Follow-up data on patients with FH-deficient atypical uterine leiomyomas revealed 19 patients alive (median follow-up 27 y) and 5 patients dead. Deaths occurred 9 to 30 years after surgery at a median age of 72 years; causes of death could not be determined. These results indicate that FH-deficient uterine leiomyomas occur with a high frequency among atypical leiomyomas and infrequently in nonatypical leiomyomas and are often histologically distinctive. They seem to have a low biological potential and lack any significant association with leiomyosarcoma.

OBJECTIVES: Advanced thymic epithelial tumors (TETs) lack adequate treatment options in part due to absence of well characterized tumor-specific antigens. Mesothelin, a cell surface antigen, has been used successfully as a target for tumor-directed therapy. We sought to determine tumor expression and serum levels of mesothelin in patients with TETs. PATIENTS AND METHODS: Tissue samples were obtained from 71 patients with histologically confirmed, unresectable advanced TETs and evaluated for mesothelin expression by immunohistochemistry. The evaluation was blinded for clinical data and outcome. Mesothelin expression and its association with clinico-pathological parameters and survival were assessed. RESULTS: Thymic carcinoma, thymoma, and thymic neuroendocrine tumors (NETs) accounted for 34 (48%), 29 (41%), and 8 (11%) cases respectively. Mesothelin expression was seen in a significantly larger proportion of thymic carcinoma (27/34, 79%) than thymoma (3/29, 10%) (P50% of tumor cells) had significantly improved overall survival (median not reached, n=19) compared to patients with no or low mesothelin expression (1.60 years; 95% CI: 1.24 to 4.94 years; n=15; HR=4.46, 95% CI: 1.55 to 12.80; p=0.0026). CONCLUSION: Mesothelin expression is frequently observed in advanced thymic carcinomas, infrequently in thymomas and is absent in thymic NETs. Due to strong, membranous expression mesothelin is a potential therapeutic target in thymic carcinoma.

Pheochromocytomas (PHEOs) and paragangliomas (PGLs) are neuroendocrine tumors that express somatostatin receptors (SSTRs), a phenomenon that constitutes a basis for tumor imaging and treatment with somatostatin analogues and peptide receptor radionuclide therapy. We studied the immunohistochemical expression of SSTR1-5 in 151 primary tumors, including 14 metastasized and 16 SDHB-deficient tumors. SSTR2 and SSTR3 were most abundantly present in these tumors, whereas the tumors were mostly negative for SSTR1, SSTR4, and SSTR5. All metastasized PGLs (9/9), but only one metastasized PHEO (1/5), were strongly SSTR2 positive. SSTR3 expression was lower in metastatic tumors and tumors with a high proliferation rate (MIB1 >= 5%), but tumors had variable individual SSTR profiles. No correlation was found between SDHB status and SSTR expression. Our results suggest that new SSTR analogues with affinity for several SSTRs could be relevant for a subgroup of patients with these tumors. Better knowledge of tumor SSTR profiles could open the door for personalized imaging and treatment in the future. Because SSTR profiles vary in PHEOs and PGLs, individual analysis is required for each tumor. (C) 2018 The Authors. Published by Elsevier Inc.

A great majority of gastrointestinal stromal tumors (GISTs) are primarily driven by gain-of-function KIT receptor tyrosine kinase mutations that subsequently lead to activation of phosphatidiylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) pathway, a downstream effector of KIT signaling. KIT tyrosine kinase inhibitor, imatinib mesylate, has been successfully used for the treatment of primary, advanced, and disseminated GISTs. Recently, activation of mTOR pathway independent of KIT signaling was demonstrated in imatinib mesylate naïve malignant GISTs and treatment-resistant metastatic tumors. This activation was attributed to oncogenic mutations in PIK3CA encoding PI3K 110α subunit, or to the inactivation of PTEN tumor suppressor, a potent mTOR negative regulator. In this study, mTOR pathway genes were evaluated in 14 imatinib mesylate naïve, KIT-mutant, malignant small intestinal GISTs using next-generation sequencing. Mutations were detected in 3 (21%) of 14 analyzed tumors: (1) c.3200A > T substitution in PIK3CB encoding PI3K 110β subunit, (2) c.1040A > G substitution in tuberous sclerosis complex (TSC2) encoding tuberin, mTOR down-regulator (3) c.6625C > G substitution in mTOR. At the protein level, these changes were predicted to cause, respectively, PIK3CB p.D1067V, TSC2 p.K347R, and mTOR p.L2209V mutations. Previously reported “in vitro” experiments with mouse 3T3 fibroblasts demonstrated oncogenic potential of PIK3CB p.D1067V and mTOR p.L2209V mutants; whereas, PolyPhen-2 software analysis predicted TSC2 p.K347R mutation to likely have a damaging impact on tuberin function. The results of this and previous studies indicate diversity of genetic changes leading to activation of PI3K-AKT-TSC-mTOR pathway in malignant GISTs. Extensive genotyping of the genes involved in mTOR pathway demonstrates common alterations that need to be considered in targeted treatment.

The spectrum of tumors arising in the salivary glands is wide and has recently been shown to harbor a network of tumor-specific fusion genes. Acinic cell carcinoma (AciCC) is one of the more frequently encountered types of salivary gland carcinoma, but it has remained a genetic orphan until recently when a fusion between the HTN3 and MSANTD3 genes was described in one case. Neither of these 2 genes is known to be implicated in any other malignancy. This study was undertaken to investigate whether the HTN3-MSANTD3 fusion is a recurrent genetic event in AciCC and whether it is a characteristic of one of its histological variants. Of the 273 AciCCs screened, 9 cases showed rearrangement of MSANTD3 by break-apart fluorescence in situ hybridization, 2 had 1 to 2 extra signals, and 1 had gain, giving a total of 4.4% with MSANTD3 aberrations. In 6 of 7 available cases with MSANTD3 rearrangement, the HTN3-MSANTD3 fusion transcript was demonstrated with real-time polymerase chain reaction . Histologically, all fusion-positive cases were predominantly composed of serous tumor cells growing in solid sheets, with serous tumor cells expressing DOG-1 and the intercalated duct-like cell component being CK7 positive and S-100 positive in 6/9 cases. All but one case arose in the parotid gland, and none of the patients experienced a recurrence during follow-up. In contrast, the case with MSANTD3 gain metastasized to the cervical lymph nodes and lungs. In conclusion, we find the HTN3-MSANTD3 gene fusion to be a recurrent event in AciCC with prominent serous differentiation and an indolent clinical course.

The neural cell adhesion molecule L1 (CD171) is a multidomain type 1 membrane glycoprotein of the immunoglobulin superfamily important in the nervous system development, kidney morphogenesis, and maintenance of the immune system. Recent studies reported CD171 expression being associated with adverse clinical outcome in different types of cancer and there has been a growing interest in targeting this cell membrane molecule on neoplastic cells by chimeric antigen receptor redirected T lymphocytes or specific antibodies. Nevertheless, conflicting results regarding the prognostic value of CD171 expression in renal cell carcinomas and gastrointestinal stromal tumors were published. In this study, CD171 expression was immunohistochemically analyzed in 5155 epithelial, mesenchymal, melanocytic, and lymphohematopoietic tumors to assess its utility in diagnostic pathology and to pinpoint potential targets for CD171-targeting therapy. A newly developed anti-CD171 rabbit monoclonal antibody, clone 014, was selected from the panel of commercially available CD171 antibodies. Immunohistochemistry was performed using Leica Bond Max automation and multitumor blocks containing up to 60 tumor samples. CD171 was constitutively and strongly expressed in neuroectodermal tumors such as schwannoma, neuroblastoma, and paraganglioma, whereas other mesenchymal tumors including schwannoma mimics showed only rarely CD171 positivity. Frequent CD171-expression was also detected in ovarian serous carcinoma, malignant mesothelioma, and testicular embryonal carcinoma. CD171 immunohistochemistry may have some role in immunophenotypic differential diagnosis of neurogenic tumors and pinpointing potential candidates for anti-CD171 therapy. Though, because of its rare expression and lack of predictive value, CD171 is neither a diagnostic nor prognostic marker for gastrointestinal stromal tumors.

Purpose: Specificity protein 1 (SP1) is an oncogenic transcription factor overexpressed in various human malignancies. This study sought to examine SP1 expression in malignant pleural mesotheliomas (MPM) and ascertain the potential efficacy of targeting SP1 in these neoplasms. Experimental Design: qRT-PCR, immunoblotting, and immunohistochemical techniques were used to evaluate SP1 expression in cultured MPM cells and MPM specimens and normal mesothelial cells/pleura. MTS, chemotaxis, soft agar, β-galactosidase, and Apo-BrdUrd techniques were used to assess proliferation, migration, clonogenicity, senescence, and apoptosis in MPM cells following SP1 knockdown, p53 overexpression, or mithramycin treatment. Murine subcutaneous and intraperitoneal xenograft models were used to examine effects of mithramycin on MPM growth in vivo. Microarray, qRT-PCR, immunoblotting, and chromatin immunoprecipitation techniques were used to examine gene expression profiles mediated by mithramycin and combined SP1 knockdown/p53 overexpression and correlate these changes with SP1 and p53 levels within target gene promoters. Results: MPM cells and tumors exhibited higher SP1 mRNA and protein levels relative to control cells/tissues. SP1 knockdown significantly inhibited proliferation, migration, and clonogenicity of MPM cells. Mithramycin depleted SP1 and activated p53, dramatically inhibiting proliferation and clonogenicity of MPM cells. Intraperitoneal mithramycin significantly inhibited growth of subcutaneous MPM xenografts and completely eradicated mesothelioma carcinomatosis in 75% of mice. Mithramycin modulated genes mediating oncogene signaling, cell-cycle regulation, senescence, and apoptosis in vitro and in vivo. The growth-inhibitory effects of mithramycin in MPM cells were recapitulated by combined SP1 knockdown/p53 overexpression. Conclusions: These findings provide preclinical rationale for phase II evaluation of mithramycin in patients with mesothelioma. Clin Cancer Res; 22(5); 1197–210. ©2015 AACR.

Primary malignant melanoma of esophagus is very rare, and its clinicopathologic and genetic features have not been extensively investigated. In this study, 20 tumors from 14 male and 6 female patients (40–79 years old) were evaluated. Dysphagia, chest pain, and weight loss were frequent symptoms. Thirteen melanomas, including two with multiple lesions, involved the distal third of esophagus. The median tumor diameter was 6 cm. Epithelioid morphology, moderate atypia, and pigmentation were typical findings. None of the patients had melanoma elsewhere, and all tumors exhibited a junctional peri-epithelial component consistent with a primary lesion. The median mitotic activity was 11 per 10 high-power fields (range, 0–31). Nine patients died of tumor within 4–22 months, however, two showed long-term (96 and 104 months) survival. In 15 cases, tissue for further immunohistochemical and molecular studies were available. BRAF, KIT, and NRAS mutation status was assessed by Sanger sequencing in all 15 tumors. The next-generation sequencing of 50 or 409 genes was performed in five and three cases, respectively. IGF1R expression indicating activation of the IGF axis was seen in 82% (9/11) of tumors. However, no BRAF mutations were identified. In 33% (5/15) of tumors, NRAS mutations were detected. KIT expression was seen in 50% (7/14) of melanomas including single KIT mutant. Two of three tumors evaluated with 409 genes panel revealed multiple driver mutations indicating sub-clonal expansion, whereas a single mutation (TSC1 p.H371Q) was the sole change in the third case. SF3B1 p.K666T and p.R625C mutations were detected in two cases. However, no co-occurrence of SF3B1 and GNAQ or GNA11 mutations, seen in uveal melanoma, was detected. FBXW7 p.R465C and p.R479G mutations, linked to cancer progression, were found in two of eight tumors. In summary, esophageal melanoma mutation profile indicates complexity of molecular mechanisms underlying its pathogenesis.

Melorheostosis is a rare hyperostotic disease of the long bones classically characterized by a "dripping candle-wax" radiographic appearance. We recently described somatic activating mutations in MAP2K1 as a cause of melorheostosis. Here, we report distinguishing characteristics of patients with MAP2K1-positive melorheostosis. Fifteen unrelated patients with radiographic appearance of melorheostosis underwent paired biopsies of affected and unaffected bone for whole-exome sequencing, histology, and cell culture. Eight patients with mutations in MAP2K1 in affected bone were compared to the seven MAP2K1-negative patients to identify distinguishing characteristics. Patients with MAP2K1-positive melorheostosis had a distinct phenotype with classic "dripping candle-wax" appearance on radiographs (p = 0.01), characteristic vascular lesions on skin overlying affected bone (p = 0.01), and higher prevalence of extraosseous mineralization and joint involvement (p = 0.04 for both). Melorheostotic bone from both MAP2K1-positive and MAP2K1-negative patients showed two zones of distinct morphology-an outer segment of parallel layers of primary lamellar bone and a deeper zone of intensely remodeled highly porous osteonal-like bone. Affected bone from MAP2K1-positive patients showed excessive osteoid (p = 0.0012), increased number of osteoblasts (p = 0.012) and osteoclasts (p = 0.04), and increased vascularity on histology in comparison to paired unaffected bone which was not seen in affected bone in most MAP2K1-negative patients. The identification of a distinct phenotype of patients with MAP2K1-positive melorheostosis demonstrates clinical and genetic heterogeneity among patients with the disease. Further studies are needed to better understand the underlying pathophysiology and associated skin findings. © 2018 American Society for Bone and Mineral Research.

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.

HRAS, KRAS, and NRAS, highly homologous proteins, are often mutationally activated in cancer. Usually, mutations cluster in codons 12, 13, and 61 and are detected by molecular genetic testing of tumor DNA. Recently, immunohistochemistry with SP174 antibody has been introduced to detect NRAS Q61R-mutant protein. Studies on malignant melanomas showed that such an approach could be a viable alternative to molecular genetic testing. This investigation was undertaken to evaluate the value of SP174 immunohistochemistry for detection of NRAS Q61R-mutant isoform. Two hundred ninety-two malignant melanomas were evaluated using Leica Bond-Max automated immunostainer. Twenty-nine tumors (10%) showed positive immunoreactivity. NRAS codon 61 was polymerase chain reaction amplified and sequenced in 24 positive and 92 negative cases using Sanger sequencing, quantitative polymerase chain reaction, and next-generation sequencing approaches. A c.182A>G substitution leading to NRAS Q61R mutation was identified in 22 tumors. Two NRAS wild-type tumors revealed c.182A>G substitutions in HRAS and KRAS codon 61, respectively. Both mutations were detected by next-generation sequencing and independently confirmed by Sanger sequencing. None of 85 NRAS codon 61 wild-type tumors and 7 NRAS mutants other than Q61R showed immunoreactivity with SP174 antibody. Thus, SP174 antibody was 100% sensitive in detecting NRAS Q61R-mutant isoform in malignant melanoma, but not fully specific as it cross-reacted with HRAS and KRAS Q61R-mutant proteins. Therefore, molecular testing is needed to determine which RAS gene is mutated. The rarity of HRAS and KRAS Q61R mutants in malignant melanoma let previous investigations erroneously conclude that SP174 is specific for NRAS Q61R-mutant protein.

Brachyury is a transcription factor of the T-box family typically expressed in notochord and chordoma. Some studies report brachyury as highly specific for chordoma, whereas others have concluded that brachyury is expressed in many types of common carcinomas by reverse transcription polymerase chain reaction and immunohistochemistry and could be involved in the epithelial-mesenchymal transition and metastatic process. In this study, we immunohistochemically evaluated 5229 different tumors for nuclear brachyury expression using a new rabbit monoclonal antibody and automated immunostaining (Leica Bond Max). Only nuclear labeling was scored, and antibody dilution of 1:2000 was used. In normal tissues, only rare cells in seminiferous tubules were labeled; all other organs were negative. All chordomas (75/76), except a sarcomatous one, were positive, whereas chondrosarcomas were negative. Among epithelial tumors, positivity was often detected in embryonal carcinoma (74%) and seminoma (45%). Pulmonary small cell carcinoma was often positive (41%), whereas pulmonary and pancreatic adenocarcinomas only rarely showed nuclear brachyury positivity (3% to 4%). Common carcinomas such as ductal carcinomas of the breast or adenocarcinomas of the prostate only exceptionally showed nuclear positivity (

Glomangiopericytoma (sinonasal-type hemangiopericytoma) is a rare mesenchymal neoplasm with myoid phenotype (smooth muscle actin-positive), which distinguishes this tumor from soft tissue hemangiopericytoma/solitary fibrous tumor. Molecular genetic changes underlying the pathogenesis of glomangiopericytoma are not known. In this study, 13 well-characterized glomangiopericytomas were immunohistochemically evaluated for β-catenin expression. All analyzed tumors showed strong expression and nuclear accumulation of β-catenin. Following this observation, β-catenin glycogen serine kinase-3 beta phosphorylation region, encoded by exon 3, was PCR amplified in all cases and evaluated for mutations using Sanger sequencing. Heterozygous mutations were identified in 12 of 13 tumors. All mutations consisted of single-nucleotide substitutions: three in codon 32 (c.94G>C (n = 2) and c.95A>T), four in codon 33 (two each c.98C>G and c.98C>T), two in codon 37 (c.109T>G), one in codon 41 (c.121A>G), and two in codon 45 (c.133T>C). At the protein level, these substitutions would lead to p.D32H, p.D32V, p.S33C, p.S33F, p.S37A, p.T41A, and p.S45L mutations, respectively. Previously, similar mutations have been reported in different types of cancers and shown to trigger activation of β-catenin signaling. All analyzed glomangiopericytomas showed prominent nuclear expression of cyclin D1, as previously shown for tumors with nuclear expression of β-catenin as a sign of oncogenic activation. These results demonstrate that mutational activation of β-catenin and associated cyclin D1 overexpression may be central events in the pathogenesis of glomangiopericytoma. In additon, nuclear accumulation of β-catenin is a diagnostic marker for glomangiopericytoma.

There is a lack of a comprehensive immunohistochemical (IHC) analysis of canalicular adenoma (CanAd), especially when combined with a description of the unique histologic features. Given the usual small biopsies, IHC may be useful in distinguishing CanAd from other tumors in the differential diagnosis. Retrospective. The patients included 54 females and 13 males (4.2:1), aged 43-90 years, with a mean age at presentation of 69.9 years. Clinical presentation was generally a mass (n = 61) slowly increasing in size (mean 38.5 months), affecting the upper lip (n = 46), buccal mucosa (n = 17) or palate (n = 4), involving the right (n = 29), left (n = 24) or midline (n = 9), without any major salivary gland tumors. The tumors ranged in size from 0.2 to 3 cm (mean 1.2 cm). Most tumors were multilobular or bosselated (76 %), often surrounded by a capsule. Histologically, the tumors were characterized by cystic spaces, tumor cords with beading, tubule formation, and by the presence of luminal squamous balls (n = 41). The cells were cuboidal to columnar with stippled chromatin. Mitoses were inconspicuous. A myxoid stroma (n = 64), sclerosis (n = 42), luminal hemorrhage (n = 51), and luminal microliths (calcifications) (n = 33) were characteristic. Nine (13.4 %) were multifocal. CanAd showed the following characteristic immunohistochemistry findings: CK-pan and S100 protein (strong, diffuse reaction); peripheral or luminal GFAP reaction; CK5/6 and p16 luminal squamous ball reaction; SOX10 nuclear reaction; cytoplasmic p63 reaction. CanAd are unique minor salivary gland tumors showing a distinct architecture and phenotype. They predilect to older women, with the majority multilobulated and affecting the upper lip, multifocal in 13 %; no major salivary gland tumors were identified. S100 protein, CK-pan, GFAP and SOX10 are positive, with luminal squamous balls highlighted by CK5/6 or p16.

BACKGROUND The primary objective of this study was to determine the safety and maximum tolerated dose (MTD) of the antimesothelin immunotoxin SS1(dsFv)PE38 (SS1P) (a recombinant antimesothelin immunotoxin consisting of a murine antimesothelin variable antibody fragment [Fv] linked to PE38, a truncated portion of Pseudomonas exotoxin A) in combination with pemetrexed and cisplatin in chemotherapy-naive patients with advanced malignant pleural mesothelioma (MPM). Secondary objectives included tumor response, SS1P pharmacokinetics, and serum biomarkers of response. METHODS Chemotherapy-naive patients with stage III or IV, unresectable, epithelial or biphasic MPM and normal organ functions were eligible. Pemetrexed (500 mg/m2 on day 1) and cisplatin (75 mg/m2 on day 1) were administered every 3 weeks for up to 6 cycles with escalating doses of SS1P administered intravenously on days 1, 3, and 5 during cycles 1 and 2. Tumor response was evaluated every 6 weeks. RESULTS Twenty-four patients received SS1P at 4 dose levels from 25 to 55 mcg/kg. Grade 3 fatigue was dose-limiting in 1 patient at 55 mcg/kg. The MTD of SS1P was established as 45 mcg/kg. Other grade 3 toxicities associated with SS1P included hypoalbuminemia (21%), back pain (13%), and hypotension (8%). Of 20 evaluable patients, 12 (60%) had a partial response, 3 had stable disease, and 5 had progressive disease. Of 13 patients who received the MTD, 10 (77%) had a partial response, 1 had stable disease, and 2 had progressive disease. Objective radiologic responses were associated with significant decreases in serum mesothelin (P=.0030), megakaryocyte potentiating factor (P=.0005), and cancer antigen 125 (P

Angiosarcoma (AS) is a rare malignant vascular tumor while epithelioid hemangioendothelioma (EHE) is a vascular tumor of low grade malignancy. CD30 is a member of the tumor necrosis factor receptor superfamily, member 8 (TNFRSF8). While expression of CD30 is most commonly associated with lymphoid malignancies or germ cell tumors, occasional angiosarcomas have been reported as CD30-positive. However, there is limited data to evaluate its role definitively in malignant vascular tumors. In this study, we evaluated 91 angiosarcomas (AS), 30 epithelioid hemangioendothelioma (EHE) from various sites, and 25 Kaposi sarcomas (KS). Overall, CD30 was expressed in 31/91 cases (34%) of AS, in 7/30 cases (30%) of EHE but in none of the KS. CD30 was expressed in a membranous staining pattern and positivity in tumor cells varied from focal to diffuse. The positive angiosarcomas included vasoformative more differentiated tumors and also solid, undifferentiated, lymphoma-like examples, one of which was classified as lymphoma prior to the era of immunohistochemistry. The CD30-expression was seen in >50% of tumor cells in a majority of angiosarcomas but only in 7% of EHEs. None of the 55 angiosarcomas studied were immunohistochemically positive for TIA-1 or granzyme B, antigens used as more specific markers for anaplastic large cell lymphoma. Compared with angiosarcoma, normal vascular endothelia of capillaries and muscular vessels showed variable positivity. Among hemangiomas, cavernous and spindle cell hemangiomas showed most frequent endothelial CD30-positivity, whereas in most other hemangiomas, CD30-positivity was scant. In conclusion, CD30 expression occurs in a significant subset of angiosarcomas and EHE and needs to be included in the differential diagnosis with other CD30-positive malignancies to avoid a diagnostic pitfall. It remains to be determined whether patients with strongly CD30-positive angiosarcomas could be candidates for targeted therapy using the recently introduced CD30 antibody drug conjugates.

In this study, we examine the clinicopathologic features of 104 cases of myxoinflammatory fibroblastic sarcoma (MIFS), a low-grade, inflammatory fibromyxoid tumor with a predilection to distal extremity soft tissue, and attempt to identify factors predictive of aggressive behavior. The study cohort consisted of 49 male and 55 female patients ranging in age from 17 to 83 (mean, 42; median, 39) years. The tumor arose primarily on the dorsal aspect of the distal extremities as a solitary and usually painless mass. Tumors ranged in size from 0.5 to 15 (mean, 3.2; median; 2.4) cm. Microscopically, tumors consisted of variably cellular and inflamed fibromyxoid tissue growing as a lobulated mass or as multiple nodules within subcutaneous tissue or along tendinofascial planes. Tumor cells ranged from plump spindled to more epithelioid cells with enlarged, vesicular nuclei. Characteristic of the process was a strikingly bizarre cell with an inclusion body–like nucleolus (85% of cases) and/or a smudgy hyperchromatic nucleus (51%) present in all but 7 cases. The mitotic rate per 50 high-power field ranged from 0 to 13 (mean, 2,9; median, 2) mitoses. Twenty-two tumors demonstrated 1 or more of the following atypical features: (1) foci with complex sarcoma-like vasculature; (2) hypercellular areas; and (3) increased mitotic activity or atypical mitotic figures. Immunohistochemically, tumor cells demonstrated immunoreactivity for vimentin (100%), D2-40 (86%), CD34 (50%), keratin(s) (33%), CD68 (27%), actin(s) (26%), desmin (9%), S-100 protein (7%), and epithelial membrane antigen (6%). Thirty of 59 patients (51%) with follow-up data suffered (at least) 1 local recurrence, and 1 patient developed metastatic disease after multiple local recurrences. Completeness of initial surgical excision was the only clinicopathologic parameter that statistically correlated with a lower incidence of recurrence (P = 0.004). Histologically atypical MIFS recurred more often than conventional tumors (67% vs. 47%), but the difference was not statistically significant (P = 0.35). Our study shows that histologic features often associated with more aggressive sarcomas do not substantially impact the morbidity of MIFS, and complete surgical excision provides the best chance for disease-free survival.

GATA3 is a transcription factor important in the differentiation of breast epithelia, urothelia, and subsets of T lymphocytes. It has been suggested to be useful in the evaluation of carcinomas of mammary or urothelial origin or metastatic carcinomas, but its distribution in normal and neoplastic tissues is incompletely mapped. In this study, we examined normal developing and adult tissues and 2040 epithelial and 460 mesenchymal or neuroectodermal neoplasms for GATA3 expression to explore its diagnostic value in surgical pathology, using monoclonal antibody (clone L50-823) and Leica Bond automated immunohistochemistry. GATA3 was expressed in trophoblast, fetal and adult epidermis, adult mammary and some salivary gland and sweat gland ductal epithelia, urothelia, distal nephron in developing and adult tissues, some prostatic basal cells, and subsets of T lymphocytes. It was expressed stronger in fetal than in adult mesothelia and was absent in respiratory and gastrointestinal epithelia. In epithelial neoplasms, GATA3 was expressed in >90% of primary and metastatic ductal and lobular carcinomas of the breast, urothelial, and cutaneous basal cell carcinomas and trophoblastic and endodermal sinus tumors. In metastatic breast carcinomas, it was more sensitive than GCDFP. Among squamous cell carcinomas, the expression was highest in the skin (81%) and lower in cervical (33%), laryngeal (16%), and pulmonary tumors (12%). Common positivity was found in skin adnexal tumors (100%), mesothelioma (58%), salivary gland (43%), and pancreatic (37%) ductal carcinomas, whereas frequency of expression in adenocarcinomas of lung, stomach, colon, endometrium, ovary, and prostate was

Diffuse malignant mesothelioma of the pleura is a highly aggressive tumor typically associated with short survival. ALCAM (CD166), a type I transmembrane protein, is a member of the immunoglobulin superfamily. In normal cells, ALCAM regulates physiological processes such as angiogenesis and immune response. In cancer, it is associated with neoplastic progression, including invasion, migration, and metastasis. Furthermore, ALCAM is considered one of the cancer stem cell markers such as ALDH1 (ALDH1A1) and SALL4. The PD-L1 (CD274)/PD-1 (PDCD1, CD279) pathway is crucial for the modulation of immune responses in normal cells. Nevertheless, pathologic activation of the PD-L1/PD-1 pathway participates in immune evasion by tumor cells. Many PD-L1–expressing tumor cells have been identified in different types of cancer, including malignant mesothelioma. In this study, 175 well-characterized primary diffuse pleural mesotheliomas, including the epithelioid (n = 148), biphasic (n = 15), and sarcomatoid (n = 12) histotypes, were evaluated immunohistochemically for cancer stem cell markers (ALCAM, ALDH1, and SALL4) and PD-L1 expression. Twenty-five percent of the mesotheliomas (43/175) expressed ALCAM, whereas ALDH1 and SALL4 positivity was seen in 1% to 2% of cases. Thirty-three percent of the analyzed tumors (57/175) contained PD-L1–positive cells. Overall survival was significantly decreased in the cohort of patients with ALCAM- or PD-L1–positive tumors (both P < .01). Furthermore, the multivariate Cox hazards regression analysis identified ALCAM and PD-L1 (both P < 0.01) as potential independent risk factors. Thus, a combination of these two markers might be useful for prognostication and planning the treatment of patients with malignant pleural mesothelioma.

Gastrointestinal (GI) involvement in chronic granulomatous disease (CGD), a rare genetic immunodeficiency, mimics other inflammatory bowel diseases. We report GI pathology from 87 CGD patients seen at the NIH Clinical Center, with vague to severe clinical symptoms, in whom biopsies (313) had been evaluated (esophagus [23], stomach [71], small bowel [52] including duodenum [39], ileum [12], and jejunum [1], and colon [167]). Additionally reviewed was GI tissue from 15 autopsies. In our patient cohort, the mean age was 22 years (age range, 3 to 44 y; 2:1 male to female ratio). There were pathologic changes in 83/87 (95%) patients; with colon being the most commonly involved site and esophagus the least. There were microgranulomas in 53/87 (61%), pigmented macrophages in 64/87 (74%), tissue eosinophilia in 31/87 (36%), and chronic and/or acute inflammation in 57/87 (66%) patients. A subset of patients had villous shortening in the duodenum (8/39) and ileum (5/12). We identify microgranulomas in 76/167 (46%) colon, 12/52 (23%) small bowel, and 4/71 (6%) gastric biopsies; pigmented macrophages in 109/167 (65%) colon and 7/52 (13%) small bowel biopsies and 14/15 autopsies; chronic and/or acute inflammation in 97/167 (58%) colon, 13/52 (25%) small bowel, 42/71 (59%) gastric, and 5/23 (22%) esophageal biopsies; tissue eosinophilia in 43/167 (26%) colon, 7/52 (13%) small bowel, and 2/71 (3%) gastric biopsies. Only 4/87 (5%) patients had normal histology. No infectious etiology was identified in the majority of inflammatory lesions. We found that mild to severe GI pathology was common in CGD. In addition, microgranulomas, pigmented macrophages, and eosinophilia are not associated with acute (neutrophilic) inflammation.

A subset (7% to 10%) of gastric gastrointestinal stromal tumors (GISTs) is notable for the immunohistochemical loss of succinate dehydrogenase (SDH) subunit B (SDHB), which signals the loss of function of the SDH complex consisting of mitochondrial inner membrane proteins. These SDH-deficient GISTs are known to be KIT/PDGFRA wild type, and most patients affected by this subset of GISTs are young. Some of these patients have germline mutations of SDH subunit genes SDHB, SDHC, or SDHD, known as Carney-Stratakis syndrome when combined with paraganglioma. More recently, germline mutations in SDH subunit A gene (SDHA) have also been reported in few patients with KIT/PDGFRA wild-type GISTs. In this study we immunohistochemically examined 127 SDHB-negative and 556 SDHB-positive gastric GISTs and 261 SDHB-positive intestinal GISTs for SDHA expression using a mouse monoclonal antibody 2E3 (Abcam). Cases with available DNA were tested for SDHA, SDHB, SDHC, and SDHD gene mutations using a hybridization-based custom capture next-generation sequencing assay. A total of 36 SDHA-negative GISTs (28%) were found among 127 SDHB-negative gastric GISTs. No SDHB-positive GIST was SDHA negative. Among 7 SDHA-negative tumors analyzed, there were 7 SDHA mutants, most germline. A second hit indicating biallelic inactivation of SDHA was present in 6 of those cases. These patients had no other SDH subunit gene mutations. Among the 25 SDHA-positive, SDHB-negative GISTs analyzed, we identified 3 SDHA mutations (1 germline), and 11 SDHB, SDHC, or SDHD mutations (mostly germline), and 11 patients with no SDH mutations. Compared with patients with SDHA-positive GISTs, those with SDHA-negative GISTs had an older median age (34 vs. 21 y), lower female to male ratio (1.8 vs. 3.1) but similar mitotic counts and median tumor sizes, with a slow course of disease in most cases, despite a slightly higher rate of liver metastases. SDHA-negative GISTs comprise approximately 30% of SDHB-negative/SDH-deficient GISTs, and SDHA loss generally correlates with SDHA mutations.

Programmed cell death 1/programmed cell death ligand (PD-1/PD-Ls) axis is crucial for the modulation of immune responses and self-tolerance. Also, aberrant PD-L1 expression on the tumor cells or tumor-associated inflammatory cells accelerates immune evasion of tumor cells. In the past decade, PD-1/PD-L immune checkpoint inhibitors were introduced to cancer treatment trials and, in some cases, showed significant anticancer effects. PD-L1 immunohistochemical staining is considered a potential predictor of clinical response to PD-1/PD-L immune checkpoint inhibitor treatment. However, immunohistochemical data on PD-L1 expression in different types of cancer especially rare entities remain incomplete. In this study, PD-L1 expression was immunohistochemically analyzed in 5536 tumors including germ cell, epithelial, mesenchymal, melanocytic/neuroectodermal, and lymphohematopoietic tumors, as well as in a set of human normal tissues including a fetus. Immunohistochemical analysis was performed with E1L3N rabbit monoclonal antibody and Leica Bond Max automation using multitumor blocks containing up to 70 tumor samples. PD-L1 was constitutively and strongly expressed in placental trophoblasts as well as choriocarcinomas and trophoblastic components of germ cell tumors. Also, the neoplastic cells of classical Hodgkin lymphoma, anaplastic large cell lymphoma, schwannoma, thymoma, and squamous cell carcinoma of various sites frequently expressed PD-L1. In gastrointestinal adenocarcinomas, PD-L1-expression was associated with EBER positivity and mismatch-repair deficiency. In addition, PD-L1 was variably expressed in non-neoplastic macrophages and dendritic cells. PD-L1 immunohistochemistry may have some role in the immunophenotypic differential diagnosis of tumors and pinpointing potential candidates for anti-PD-1/PD-L immune checkpoint therapy.

Background Despite the near universal occurrence of activating codon 12 KRAS somatic variants in pancreatic cancer, there is considerable heterogeneity in the molecular make-up, MAPK/ERK pathway activation states, and clinical outcome in this disease. We analyzed the expression levels of CNKSR1, a scaffold that influences MAPK/ERK pathway activity, in clinical pancreas cancer specimens and their impact on survival of patients with pancreatic cancer. Methods Immunohistochemical staining for CNKSR1 expression was performed on 120 specimens from three independent pancreatic cancer tissue registries, phospho-ERK levels were measured in 86 samples. Expression was divided into CNKSR1 low and CNKSR1 high and correlated with clinicopathological variables including overall survival using multivariate Cox proportional hazard ratio models. Results CNKSR1 expression was increased in tumors compared to matched normal uninvolved resection specimens (p = 0.004). 28.3% (34/120) of patient specimens stained as CNKSR1 low compared to 71.7% (86/120) of specimens which stained as CNKSR1 high. High CNKSR1 expression was more prevalent in low grade tumors (p = 0.04). In multivariate analysis, low CNKSR1 expression status was independently correlated with decreased overall survival (HR = 2.146; 95% CI 1.34 to 3.43). When stratifying primary, non-metastatic tumor biopsies by CNKSR1 expression, resection was associated with improved survival in patients with high CNKSR1 expression (p

The CD274 (PD-L1)/PDCD1 (PD-1) pathway is crucial for the modulation of immune responses and self-tolerance. Aberrantly expressed CD274 allows tumor cells to evade host immune system and is considered to be a mechanism of adaptive immune resistance. Inhibition of the CD274/PDCD1 immune checkpoint offers a promising new therapeutic strategy. Although CD274-expressing tumor cells have been identified in different types of tumors including colorectal cancer, clinicopathologic profile of these CD274-positive tumors has not been extensively studied. In this study, 454 primary colorectal carcinomas were analyzed histologically and immunohistochemically for CD274, mismatch repair (MMR) proteins, intestinal differentiation marker (CDX2), and stem cell markers (ALCAM, ALDH1A1, and SALL4). CD274-positive colorectal carcinomas (54/454 (12%)) usually (83%) involved the right or transverse colon with poorly differentiated and solid/medullary histology. On the basis of multivariate logistic regression analysis, CD274 positivity was significantly associated with poorly differentiated histotype (OR: 3.32; 95% CI: 1.46–7.51; P = 0.004), MMR deficiency (OR: 10.0; 95% CI: 4.66–21.5; P

Two cancer testis antigens, the New York esophageal squamous cell carcinoma-1 (NY-ESO-1) and the melanoma-antigen family A (MAGE-A), represent promising immunotherapy targets due to the low expression of these antigens in nonmalignant tissue. To assess overexpression patterns in various cancers, we performed a systematic immunohistochemical analysis for NY-ESO-1 and MAGE-A on tissue array samples of 3668 common epithelial carcinomas (CA) and germ cell tumors of high prevalence and mortality. Here, we find significantly higher expression of MAGE-A (>50% on tumor cells) compared with NY-ESO-1 in several CAs including cutaneous squamous cell carcinomas (SCC) (52.8%/2.8%), esophageal SCC (50%/0%), head and neck SCC (41.1%/

Although schwannoma and neurofibroma tumors are generally reported as distinct pathologic diagnoses, sporadic schwannoma/neurofibroma hybrid nerve sheath tumors have been reported in the general population with components of both entities. We report the clinicopathological features of these hybrid nerve sheath tumors in patients with neurofibromatosis type 2 (NF2). A retrospective review of nerve sheath tumor surgical specimens from patients with NF2 enrolled at the National Institutes of Health was performed. Those specimens reported to have schwannoma-like and neurofibromalike features were selected for further characterization by morphology, immunohistochemical panel (CD34, S100, neurofilament triplet protein (immunostain) (NFTP), epithelial membrane antigen (EMA)), and confirmation as hybrid tumors. Of 43 total NF2 patients undergoing resection of nerve sheath tumors, 11 specimens from 11 (26%) patients were found to be benign nerve sheath tumors exhibiting hybrid features of both neurofibroma and schwannoma. Immunohistochemical studies showed the schwannoma component to be S100+, CD 34- while the neurofibroma component was CD34+, variable S100+. Our experience emphasizes the importance of including this distinct tumor subtype, the schwannoma/neurofibroma hybrid tumor, in the differential diagnosis of nerve sheath tumors in NF2 patients and suggests that the relationship between neurofibroma and schwannoma tumors is closer than previously suspected..

Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors usually driven by the mutational activation of receptor tyrosine kinases, KIT, or PDGFRA. Oncogenic activation of phosphatidylinositide-3-kinase (PI3K), a downstream effector in the KIT signaling pathway, has been identified in different types of cancer, with the PI3K 110α subunit encoded by PIK3CA being a common mutational target. In this study, the mutational hotspot in the PIK3CA kinase domain encoded by exon 20 was evaluated in 529 imatinib-naive GISTs using PCR amplification and Sanger sequencing. Eight mutations (two co-existing in one tumor) were identified. Subsequently, The cobas PIK3CA Mutation Test was employed to evaluate mutational hotspots in exons 1, 4, 7, and 9 in 119 PIK3CA exon 20-wild type tumors. In two cases, mutations in exons 1 and 9 were identified. In one GIST, previously undetected by Sanger sequencing, the exon 20 mutation was discovered. Altogether, eight primary and two metastatic GISTs carried PIK3CA mutations. The size of primary PIK3CA-mutant GISTs was ≥ 14 cm (mean size 17 cm), and mitotic activity varied from 0 to 72 per 50HPF (mean 5/50HPF). Follow-up data showed short survival in 6 of 7 studied cases. Detection of PIK3CA mutations in large or metastatic KIT-mutant GISTs may suggest that PIK3CA-mutant clones have a proliferative advantage during disease progression. Tyrosine kinase inhibitors have been successfully used in GIST treatment. However, resistance frequently develops due to secondary KIT mutations or activation of downstream to KIT signaling pathways, such as the PI3K/AKT/mTOR pathway. PIK3CA mutations similar to the ones detected in GISTs have been shown to cause such activation. Therefore, genotyping of PIK3CA in GISTs might help to pinpoint primary and metastatic tumors with the potential to develop resistance to tyrosine kinase inhibitors and guide therapy with PI3K inhibitors.

Signet ring stromal cell tumor (SRSCT) of the ovary is a very rare benign ovarian neoplasm. To date, no underlying genetic mechanism has been identified. In this study, 50 oncogenes and tumor suppressor genes were evaluated for mutations in a typical SRSCT using the next-generation DNA sequencing approach. An in-frame deletion of 30 nucleotides in the glycogen serine kinase-3 beta phosphorylation region of the β-catenin gene (CTNNB1) was identified, and the finding was confirmed by Sanger sequencing. This deletion (c.68_97del) at the protein level would lead to a p.Ser23_Ser33delinsThr oncogenic-type mutation. Subsequent immunohistochemistry showed prominent nuclear accumulation of β-catenin and cyclin D1 in tumor cells. Thus, mutational activation of the Wnt/β-catenin pathway could be a crucial event in the molecular pathogenesis of SRSCT of the ovary. These findings may also assist in the diagnosis of this rare tumor.

Schwannoma is a rare gastrointestinal mesenchymal tumor, as the vast majority of gastric mesenchymal tumors are gastrointestinal stromal tumors. In this study, we analyzed clinicopathologically 51 gastric schwannomas. These tumors predominantly occurred in older adults with a marked female predominance (40 women and 11 men; median and mean ages, 60 and 58 years). They variably presented with gastric discomfort, bleeding, or rarely gastric outlet obstruction; and many were incidental findings during other medical procedures. The tumors ranged from 1 to 10.5 cm (median, 4.5 cm). The typical histologic features included spindle cells usually with microtrabecular architecture and focal nuclear atypia, and peritumoral lymphoid cuff, whereas features of soft tissue schwannomas, such as encapsulation, nuclear palisading, vascular hyalinization, and dilatation, were absent or infrequent. Median mitotic count was 2/50 high-power fields, with the highest count being 13/50 high-power fields. No malignant variants were recognized, and long-term follow-up did not reveal recurrences or metastases. Immunohistochemically, all examined tumors were S100 protein positive and most were also GFAP positive, whereas CD34 and NF68 were encountered rarely and all tumors were negative for HMB45, KIT, DOG1/Ano 1, smooth muscle actin, desmin, and synaptophysin. None of the 9 tumors studied contained gastrointestinal stromal tumor-specific KIT or PDGFRA mutations. Fluorescence in situ hybridization studies revealed multiple signals with BCR probe (chromosome 22) and centromeric probes for chromosomes 2 and 18 suggesting polyploidy. These findings indicate that gastric schwannoma is a distinctive form of peripheral nerve sheath tumor that in many ways differs from soft tissue schwannoma. It should be distinguished from gastrointestinal stromal tumor and other mesenchymal tumors of the gastrointestinal tract, such as the S100 protein-positive gastrointestinal clear cell sarcoma and metastatic melanoma.

Benign fibro-osseous lesions (BFOLs) frequently display overlapping histological features. The differentiation of fibrous dysplasia (FD) from other BFOLs can be difficult, even for experienced orthopedic pathologists. Accurately distinguishing FD from other BFOLs may have significant clinical and treatment implications. A somatic mutation in gene GNAS encoding the α subunit of the G protein (Gsα) involving the codon corresponding to Arg 201 has been identified in FD and is specifically absent in other BFOLs. We have developed a quantitative assay by pyrosequencing that has a detection sensitivity of 95%. The test allows the identification of the two most common types of mutation (Arg→His and Arg→Cys) in a single reaction, with the ability to analyze other rare mutations. Of the 24 FD cases in this series, 23 (96%) were positive for GNAS/Gsα mutation. Nineteen of 23 positive cases exhibited a G→A mutation (Arg→His), whereas four had a C→T mutation (Arg→Cys). One of three BFOL, not otherwise specified cases was positive for G→A mutation. None of the osteofibrous dysplasia, ossifying fibromas, or other bone lesions were positive for this mutation. Our experience is that pyrosequencing is an easy and accurate quantification method for Gsα mutation detection in fibrous dysplasia. Mutation analysis of the Gsα by pyrosequencing has significant potential for improving discrimination between FD and other BFOLs in problematic cases.

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.

Gastrointestinal stromal tumors sometimes occur together with gastric carcinoma, but true collision tumors featuring these 2 components are very rare. The authors describe here 2 collision tumors containing a gastrointestinal stromal tumor with intermingling elements of gastric adenocarcinoma. The gastrointestinal stromal tumors were 5.5 to 6 cm spindle cell tumors, and one patient had an additional prepyloric stromal tumor (2.5 cm). All gastrointestinal stromal tumors had low mitotic counts less than 5/50 high-power fields and were positive for KIT, DOG1, and CD34. Different KIT exon 11 mutations (single nucleotide substitution, complex insertion-duplication) in all tumors indicated that the 2 gastrointestinal stromal tumors in one patient were independent primary tumors. The adenocarcinoma components displayed gland-forming intestinal type to signet ring cell morphology with focally accompanying dysplastic epithelium, immunohistochemical positivity for CDX2, and varying keratin 7/20 expression. We hypothesize that development of gastric adenocarcinoma within a gastrointestinal stromal tumor may be based on displaced gastric epithelium in a long-standing stromal tumor with events of intermittent ulceration and epithelial regeneration.

A great majority of gastric mesenchymal tumors are gastrointestinal stromal tumor (GIST). A rare group of non-GISTs include myxoid mesenchymal neoplasms. In this report, we describe 12 cases of a distinctive gastric tumor, named here as plexiform fibromyxoma. These tumors occurred in 5 men and 7 women of ages 7 to 75 years (median, 41 y). All tumors were located in the gastric antrum and 6 of them also extended into extragastric soft tissues or into the duodenal bulb. The tumors measured from 3 to 15 cm (median, 5.5 cm). Histologically typical was a plexiform intramural growth with multiple micronodules containing paucicellular to moderately cellular myxoid to collagenous and fibromyxoid neoplastic elements. A prominent, sometimes plexiform capillary pattern was typically present. Extramural components included subserosal nodules, and sometimes more cellular, solid nonplexiform spindle cell proliferation. The tumor cells varied from oval to spindled and had limited atypia and mitotic activity < 5/50 high-power fields. Frequent ulceration, mucosal invasion, and vascular invasion (4 cases) had no adverse significance in these tumors. Immunohistochemically, the tumor cells were positive for alpha smooth muscle actin, and variably for CD10, and were consistently negative for KIT, DOG1, CD34, desmin, and S100 protein. No KIT or platelet-derived growth factor receptor alpha mutations were present in the 3 examined cases. None of the 4 patients who were followed from 9 to 20 years (median, 19 y) developed recurrences or metastases. Additional 3 patients survived 14 to 25 years with unknown tumor status. Review of large numbers of mesenchymal tumors in the esophagus and intestines did not reveal similar tumors. Plexiform fibromyxoma is a distinctive benign gastric antral neoplasm that should be separated from GIST, nerve sheath tumors, and other fibromyxoid neoplasms.

This report describes 3 cases of a distinctive, hitherto unreported gastric epitheliomesenchymal biphasic tumor that differs from other biphasic tumors of the stomach and elsewhere: carcinosarcoma, biphasic synovial sarcoma, teratoma, and mixed tumor. The tumors occurred in young adults, 2 males and 1 female, of ages 19, 27, and 30 years. Two tumors were located in the greater curvature in the gastric body and one in the antrum. The tumors measured 5, 6, and 15 cm in maximum diameter, and their mitotic rates were 0, 4, and 30 mitoses per 50HPF. There were 2 components: uniform oval or spindled cells in diffuse sheets, and clusters or cords of epithelial cells occasionally forming glandular structures with small lumens. The epithelial elements were positive for keratin cocktail AE1/AE3, keratin 18, and partly for keratin 7, but were negative for keratins 5/6, 20 and epithelial membrane antigen. The spindle cells were positive for vimentin and CD10. All components were negative for CD34, CD99, estrogen receptor, KIT, smooth muscle actin, desmin S100 protein, p63, calretinin, chromogranin, synaptophysin, CDX2, and thyroid transcription factor 1. In situ hybridization for SS18 rearrangement was negative in all cases separating this tumor from synovial sarcoma. All 3 patients were alive after follow-up of 3.5, 5, and 14 years. Because these tumors have some resemblance to blastomas of other organs, we propose the term "gastroblastoma" for this distinctive, at least low-grade malignant epitheliomesenchymal tumor of the stomach.