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Objectives Epithelioid sarcoma (ES) rarely arises in the nerve. To increase our understanding of this unusual tumor originating in the nerve, we describe the features of three cases and review the literature. Methods Clinical data, imaging, pathology, treatment, and follow-up are detailed. A systematic literature review was conducted. Results Two patients were male and one female; the median age was 24 years. The patients had neurologic symptoms, and the tumors arose in large nerves and ranged from 2.4 to 5.8 cm. The tumors were avid on positron emission tomography–computed tomography and showed increased signal intensity on T2-weighted magnetic resonance imaging. Centered in the nerve, the tumors grew with an infiltrative pattern and encased the nerve fascicles. All were treated with wide resection, and adjuvant treatment included combinations of chemotherapy and radiation. One recurred, and the limb was amputated. Metastases were documented to lymph nodes, lung, pleura, and skin. One patient died of disease after 54 months. Literature review including our cases showed that tumors stained with pancytokeratin (9/9), EMA (4/4), and CD34 (7/7); there was loss of INI1 in all six cases tested. Conclusions ES rarely arises in the peripheral nerve, and its infiltrative nature often requires morbid surgery. The differential includes a variety of benign and malignant epithelioid neoplasms.

Objectives: Aberrant expression of neuroendocrine markers has been reported in angiosarcomas and can occasionally result in diagnostic confusion. The aim of this study was to evaluate the expression of insulinoma-associated protein 1 (INSM1), a marker for neuroendocrine differentiation, in angiosarcomas as well as other sarcomas. Methods: Tissue microarrays, including angiosarcoma, Ewing sarcoma, desmoplastic small round cell tumor (DSRCT), clear cell sarcoma, synovial sarcoma, leiomyosarcoma, alveolar soft part sarcoma, epithelioid sarcoma, and undifferentiated pleomorphic sarcoma, were evaluated for expression of INSM1. The extent of immunoreactivity was graded according to the percentage of positive tumor cell nuclei (0, no staining; 1+, Results: INSM1 expression was found in a subset of angiosarcomas (n = 24/94, 26%; majority 5+, weak to moderate), as well as DSRCTs (n = 7/62, 11%; 2+, weak to strong) and rarely synovial sarcomas (n = 3/76, 4%; 2+, moderate to strong). No INSM1 expression was detected in the other sarcomas. Conclusions: Aberrant expression of INSM1 can be seen in a subset of angiosarcomas often with diffuse labeling. Other sarcomas that can rarely demonstrate small cell morphology and focal INSM1 expression include DSRCT and synovial sarcoma.

Introduction/Objective Epithelioid sarcoma (ES) is a rare, malignant mesenchymal neoplasm that has a known tendency for local recurrence, regional lymph node involvement, and distant metastases. Two histologic variants have been recognized: classic ES also known as the distal type, and proximal-type ES (PES). The classic ES is common in young adults. It occurs more frequently in the distal upper extremities followed by the distal lower limbs and has a male prevalence of 2:1. Conversely, PES commonly involves deep tissues in the pelvic region, including the genital area. It tends to occur in older patients and follows a more aggressive clinical course. In the female genital tract, PES occurs most frequently in the vulva. The incidence of primary sarcoma of the vulva accounts for 1.5-5% of all malignant tumors, making PES a very rare incidence. Methods/Case Report Here we report a 60-year-old female diagnosed with vulvar epithelioid sarcoma treated with a right radical vulvectomy and bilateral inguinal lymph node dissection in 2008. In 2017, further surgery and adjuvant radiation were given for local recurrence. In 2020, the patient developed left hip pain and was found to have an expansile lytic lesion in the left proximal femur. Extensive resection was performed. Grossly the vulvar lesion was nodular with diffuse hemorrhage, degeneration, and necrosis. Microscopically, the tumor cells had large vesicular nuclei, prominent nucleoli, and abundant eosinophilic cytoplasm. Histologically, the morphology of the tumor cells are similar for the primary vulvar specimen and the bone metastases. Immunohistochemically, the tumor cells are positive for vimentin, GATA, FLI-1, SMA, SMHC, partially positive for CAM5.2, AE1/AE3, CD31, and CD163. Immunohistochemistry was negative for CDX2, CD56, S-100, TTF-1, CK5/6, CK20, P40, mammoglobin, MOC31, ER, CK7, CK903, HMB45, PAX8. A Ki-67 proliferative index was around 30-40%. NGS molecular testing detected a SMARCB1 mutation with loss of exons 1-3 and exons 7-9 supporting the diagnosis of epithelioid sarcoma. Results (if a Case Study enter NA) NA Conclusion In summary, we report a case of PES of the vulva in a 60 year old female. Grossly, the lesion was nodular with histology showing large vesicular nuclei, prominent nucleoli, and abundant eosinophilic cytoplasm. It showed loss of INI1/SMARCB1 nuclear expression. The patient is receiving further adjuvant treatment and shows no new metastases.

Background Epithelioid sarcoma, a rare soft tissue malignancy, is clinically aggressive and commonly affects distal extremities. Proximal, fibroma-like, and angiomatoid variants are lightly outlined. The proximal variant is the most aggressive, composed of larger cells and rhabdoid features, characteristically captivating one’s attention to rhabdomyosarcoma. We present a rare epithelioid sarcoma that histologically mimicked pleomorphic rhabdomyosarcoma of jaw in a 31-year-old male. Objectives To discuss histopathological features of epithelioid sarcoma of rhabdoid features, distinguishing it from other histological mimics like rhabdomyosarcoma. Methods A 31-year-old male was admitted at Muhimbili National Hospital in October 2017 with a 4-month history of slow-growing tender ulcer on the lower right jaw and right-side facial swelling. Clinical impression was squamous cell carcinoma with differential of adenocarcinoma. Various laboratory investigations, imaging, routine staining, and immunohistochemistry were performed. Results CT scan revealed a heterogenous mass in the right submandibular region. Initial examination from incision biopsy showed large oval pleomorphic tumor cells with enlarged vesicular nuclei and abnormal mitoses. Wide excision biopsy followed after conclusion of poorly differentiated carcinoma. Its examination revealed a diffuse, nodular tumor with large, polygonal, round, spindle cells displaying abundant deeply eosinophilic cytoplasm, sometimes showing eccentric vesicular nuclei. Rhabdoid features were observed. Immunohistochemistry revealed strong positivity for wide-spectrum cytokeratin, vimentin, and CD99 and was negative for EMA and myogenin. Conclusion Morphology by routine stains suggested both epithelial and mesenchymal malignancy. Cells with rhabdoid features suggested pleomorphic rhabdomyosarcoma with differential of epithelioid sarcoma. Cytokeratin, vimentin, and CD99 confirmed the diagnosis of epithelioid sarcoma, proximal variant. This case adds information on this rare entity emphasizing application of diagnostic immunohistochemistry procedures in the platform for confirmation of diagnosis to assist in proper patient management.

p63 is a p53 homolog that is expressed in various normal epithelial tissues and epithelial malignancies. Its expression in mesenchymal lesions has not been examined in depth; therefore, we studied p63 expression by immunohistochemical analysis in 650 soft tissue tumors. We found that p63 expression is limited in soft tissue tumors. The majority of tumors studied were p63-, including all cases of angiosarcoma, lipomatous neoplasms, dermatofibrosarcoma protuberans, solitary fibrous tumor, schwannoma, neurofibroma, gastrointestinal stromal tumor, and leiomyosarcoma. Nuclear p63 reactivity was found in a subset of soft tissue myoepithelioma and myoepithelial carcinoma of soft tissue, cellular neurothekeoma, soft tissue perineurioma, Ewing sarcoma/peripheral neuroectodermal tumor, diffuse-type giant cell tumor, and giant cell tumor of soft parts. Infrequent, weak, or focal p63-staining patterns were observed in low-grade fibromyxoid sarcoma, malignant peripheral nerve sheath tumor, extraskeletal myxoid chondrosarcoma, myxofibrosarcoma, proximal-type epithelioid sarcoma, synovial sarcoma, embryonal rhabdomyosarcoma, desmoplastic small round cell tumor, atypical fibroxanthoma, and spindle cell melanoma. Absent p63 expression is typical for most soft tissue tumors, including most (but not all) that would be in the differential diagnosis of spindle cell squamous carcinoma.

Epithelioid sarcoma (ES) is rare with a poor prognosis and for which a loss of INI1 expression has been recently reported. We report a study of 106 cases with clinical, histologic, and immunohistochemical data, including INI1 expression, and follow-up data. Of the 106 cases, 70 were the conventional subtype and 36 the large cell subtype. INI1 was negative in 86 cases (81.1%): 57 (81%) of 70 conventional and 29 (81%) of 36 large cell subtypes. Treatment modalities were available for 76 and follow-up for 80 patients. Of the 80 patients, 43 (54%) experienced metastasis and 25 (31%) died of the disease. Univariate analysis indicated that tumor size and mitotic index were significant for metastasis-free survival, whereas proximal location, tumor size, tumor multifocality, and mitotic index were significant for overall survival. Loss of expression of INI1 is frequent in the conventional and large cell subtypes of ES and can be used as a diagnostic marker, but it has no prognostic impact.

We studied the expression of CD2, CD3, CD4, CD5, CD7, CD8, CD56, and CD138 in 447 cases of common human neoplasms with epithelioid features. CD2, CD3, CD4, and CD8 antigens were detected in none of 447 cases of nonhematopoietic tumors. CD5 and CD7 antigens were expressed in 12.3% and 19.5% of cases of nonhematopoietic tumors, respectively. Their expression was found primarily in adenocarcinomas from the gastrointestinal tract, breast, and female reproductive organs. The high expression of CD5 and CD7 antigen in pancreatic ductal carcinoma and cholangiocarcinoma and high expression of CD7 in epithelioid sarcoma may have diagnostic value. One quarter of cases were positive for CD56. Overexpression of CD56 antigen was detected mainly in neuroendocrine tumors or adenocarcinomas with neuroendocrine differentiation. Its consistent overexpression in adrenal cortical and thyroid tumors may have diagnostic usefulness. Virtually all tumor types studied were CD138+ with a variable positivity rate. The negative staining of CD138 in malignant mesothelioma may be useful for separating mesothelioma from metastatic adenocarcinoma.

A patient with a recurrent epithelioid sarcoma of the hand was observed for five years with a diagnosis of nodular fasciitis. Eventually, the patient had a pulmonary metastasis and diffuse bone marrow spread, which was associated with a leukemoid reaction. Bone marrow dissemination by sarcoma is unusual, and its production of a leukemoid reaction very rare; this is its first reported occurrence in epithelioid sarcoma that the authors have been able to identify in the literature.

The immunohistochemical findings in 14 epithelioid sarcomas, neoplasms of uncertain histogenesis, indicate that they react with antibodies against cytokeratin, epithelial membrane antigen, and vimentin. All cases were nonreactive for leukocyte common antigen, myoglobin, and Factor VIII-related antigen. These results point to the fact that epithelioid sarcoma expresses phenotypic characteristics more often associated with epithelioid neoplasms, rather than the mesenchymal profile of most soft tissue sarcomas. One explanation for this observation is that epithelioid sarcoma is in fact a carcinoma originating in the deep soft tissues. On the other hand, the pluripotential mesoderm has a known embryonic capacity to differentiate into epithelium and, therefore, it is plausible that epithelioid sarcoma is a mesenchymally derived neoplasm. Aside from histogenetic considerations, epithelioid sarcoma may be confused with a number of other neoplastic and granulomatous processes. Differential immunohistochemical stains are useful in selected instances wherein light and electron microscopic findings are diagnostically equivocal.