Proximal epithelioid sarcoma--a misnomer

Epithelioid sarcoma of the pretragus: a rare pediatric entity with an unusual site

Epithelioid sarcoma (ES) is a rare soft tissue tumor that is commonly misdiagnosed. It is a mesenchymal tumor that shows both mesenchymal and epithelial features. It tends to occur in the distal upper extremity in children and young adults but may appear in any location and any age group. Less than 1% of ES involve the head and neck. Clinically, the tumor can be mistakenly confused with a benign lesion as it can mimic nonspecific ulcers or infected warts. Histologically, ES is characterized by a nodular architecture and epithelioid appearance of cells centered with necrosis, mimicking a granulomatous process. We present the clinical history of a 12-year-old male who presented with an ES of the pretragus with a brief review of the literature to raise awareness on this rare entity and to discuss the challenges in managing histopathological differential diagnosis in front of this unusual clinical presentation.

Metastatic Epithelioid Sarcoma of the Eyelid in a 47-Year-Old Man: A Case Report

Epithelioid sarcoma is a rare soft tissue neoplasm of uncertain differentiation that typically affects the distal extremities. Primary orbital epithelioid sarcoma is rare, and no reports exist characterizing metastases of this tumor to the orbit and ocular adnexa. In this article, the authors describe a rare case of eyelid metastasis in a 47-year-old man with epithelioid sarcoma of the right fibula diagnosed 16 months earlier who was otherwise doing well on the adjuvant tazemetostat therapy. In addition, the authors perform a retrospective review of cases of primary orbital epithelioid sarcoma reported in the literature, of which 4 patients responded favorably to surgical excision whereas 2 others eventually died as a direct result of their disease.

Clinicopathological analysis of myxoid proximal-type epithelioid sarcoma

Proximal-type epithelioid sarcoma (ES) with a diffuse myxoid stroma is rare. Here, we report the case of a 33-year-old man with a perineal mass. Imaging showed the presence of a poorly demarcated 6.9 × 5.3-cm mass in the subcutaneous perineal region. Macroscopic examination showed that the resected tissues were partially necrotic. Histological examination showed that the tumor comprised numerous large or pleomorphic epithelioid cells with large vesicular nuclei and prominent nucleoli. A clear background of necrosis and inflammatory exudates was also present. Immunohistochemical examination showed that the tumor cells were positive for vimentin and CD34 - both of which were expressed throughout the cytoplasm - but typically did not express nuclear INI1 (SMARCB1). Hematoxylin-eosin staining (HE staining) showed that the mucin content of the tumor was approximately 80%. The patient was diagnosed with proximal-type ES with myxoid features. The patient died due to disease progression after 2 months of follow-up and without undergoing further treatment in our department. To our knowledge, only 2 cases of proximal-type ES with diffuse myxoid stroma have been reported. Proximal-type ES is rare, and this is the first case report of proximal ES with myxoid features in the perineal area.

Epithelioid Sarcoma: Diagnostic Features and Genetics

Epithelioid sarcoma (ES) is a rare, aggressive soft-tissue neoplasm of uncertain differentiation, characterized by nodular aggregates of epithelioid cells, which are immunoreactive to cytokeratins (CKs) and epithelial membrane antigen, and often for CD34. It has a propensity for multifocal disease at presentation, local recurrence, and regional metastasis. These are aggressive neoplasms with particularly poor prognosis after regional or distant metastatic disease, for which surgical resection is still the mainstay of treatment, and options for patients with metastatic disease remain undefined. There are 2 distinct variants: classic ES, which typically presents as a subcutaneous or deep dermal mass in the distal extremities of young adults and comprises nodular distributions of relatively uniform epithelioid cells with central necrosis, and the proximal variant, which has a predilection for proximal limbs and limb girdles and the midline of the trunk, which is composed of sheets of larger, more atypical cells with variable rhabdoid morphology. Both classic and proximal-type ESs are associated with the loss of SMARCB1/INI1 protein expression, but appear otherwise molecularly relatively heterogeneous. We review classic and proximal-type ES, discussing morphology, immunohistochemical and genetic findings, the differential diagnosis, and the future potential for targeted therapies.

Soft tissue tumors of uncertain origin

Many soft tissue tumors of childhood lack obvious differentiation toward a defined mesenchymal tissue type or have a phenotype that does not correspond to any defined normal tissue. These challenging tumors are currently regarded as neoplasms of uncertain differentiation. Nonetheless, there have been great strides in the understanding of their pathologic and genetic features and biologic underpinnings. The application of new genetic information to the pathologic diagnosis among this group of tumors is an emerging area in diagnostic pediatric pathology. This article reviews the clinicopathologic features of tumors of uncertain and/or miscellaneous origin, with an emphasis on the unique aspects of these neoplasms in children and adolescents, use of diagnostic adjuncts, and differential diagnosis.

Epithelioid sarcoma

Epithelioid sarcomas are rare, mesenchymal tumors of unknown histogenesis and display multidirectional differentiation, which is predominantly epithelial. They have no normal cellular counterpart and differ from both synovial sarcoma and carcinoma. They account for less than 1% of all soft tissue sarcomas and are usually slow growing, with peak incidence in young adult men and occur predominantly in extremities. Histologically, they form nodules, with central necrosis surrounded by bland, polygonal cells with eosinophilic cytoplasm and peripheral spindling. They regularly express vimentin, cytokeratins, epithelial membrane antigen, and CD34, whereas staining is usually negative with S100, desmin, and FLI-1. Ultrastructurally, they display epithelial and mesenchymal features, including myofibroblastic differentiation. They manifest no specific cytogenetic findings, but several cases have displayed chromosomal abnormalities in 22q region. Clinically, they have a high recurrence rate, and up to 50% of epithelioid sarcomas metastasize. Proximal, fibroma-like, and angiomatoid variants have been described. The proximal variant (with larger cells, prominent nucleoli, and rhabdoid changes) is clinically more aggressive.

Proximal-type epithelioid sarcoma with elevated serum CA 125: report of a case with CA 125 immunoreactivity

Proximal-type epithelioid sarcoma is a recently described rare soft tissue neoplasm. It is commonly found in the pelvic, perineal, and genital areas in middle-aged or older adults, as compared with the classic type of epithelioid sarcoma, which arises in the distal portion of the extremities in adolescents and young adults. Proximal-type epithelioid sarcoma has a more aggressive clinical behavior than the classic type of epithelioid sarcoma. Proximal-type epithelioid sarcoma is histologically characterized by a diffuse proliferation of epithelioid cells with prominent rhabdoid feature. Recently, a few cases have been reported of epithelioid sarcoma with elevated serum CA 125 level and CA 125 immunoreactivity in neoplastic cells. These cases raise the possibility that serum CA 125 and CA 125 immunoreactivity could be a useful tumor marker for diagnosing and monitoring epithelioid sarcoma. We describe a case of proximal-type epithelioid sarcoma with elevated serum CA 125 level (up to 3395 U/mL [reference range, <35 U/mL]) in a 12-year-old girl who presented with a huge pelvic mass measuring 12 cm in greatest dimension. The serum CA 125 level dropped to 452 U/mL after a debulking operation of the mass. Immunostaining for CA 125 demonstrated a positive immunoreactivity in the neoplastic cells. She received one cycle of chemotherapy and died of the disease 2 months after diagnosis. This case represented a rare example of proximal-type epithelioid sarcoma with elevated serum CA 125 and immunoreactivity for CA 125 in the tumor cells. Based on the previous reported cases and the current case, serum CA 125 as well as immunohistochemical stain for CA 125 may be a useful tumor marker of proximal-type epithelioid sarcoma.

Epithelioid sarcoma of Enzinger

Epithelioid sarcoma was named in 1970 in a classic paper by Enzinger, who expanded the observations in a larger series in 1985. He defined a sarcoma with a peak incidence in young adult males and a predilection for extremities, involving subcutis or deeper tissue and extending along tendon sheaths or aponeuroses. The tumor forms nodules with central necrosis surrounded by bland polygonal cells with eosinophilic cytoplasm and peripheral spindling. Fibromalike, angiomatoid, and proximal aggressive variants (with larger cells, prominent nuceloi, and rhabdoid change) have since been described. Epithelioid sarcomas regularly express vimentin, cytokeratins, and epithelial membrane antigen, and about half are positive for CD34, but a wide range of other antigens can be expressed. S100 protein, desmin, and FLI-1 are usually negative. The ultrastructure displays epithelial and mesenchymal features including myofibroblastic differentiation. There are no specific genetic findings but several cases display chromosomal abnormalities in the 22q region. The tumor has no normal cellular counterpart and differs from both synovial sarcoma and carcinoma. There is a wide differential diagnosis from numerous benign and malignant conditions, including granuloma annulare, melanoma, and epithelioid vascular neoplasms. Epithelioid sarcoma has a high recurrence rate, which can be reduced by adequate surgery, and up to 40% metastasize, to regional lymph nodes, to lung, and other locations including scalp. Adverse prognostic factors include large size, male sex, older age, necrosis, vascular invasion, rhabdoid cytomorphology, and inadequate excision. Thirty-six years after Enzinger's original account, epithelioid sarcoma remains a clinically and pathologically distinct, indolent but aggressive sarcoma of indeterminate lineage.

SMARCB1/INI1Tumor Suppressor Gene Is Frequently Inactivated in Epithelioid Sarcomas

Epithelioid sarcoma is a rare soft tissue neoplasm of uncertain lineage that usually arises in the distal extremities of adults, presents a high rate of recurrences and metastases and frequently poses diagnostic dilemmas. The recently reported large-cell "proximal-type" variant is characterized by increased aggressiveness, deep location, preferential occurrence in proximal/axial regions of older patients, and rhabdoid features. Previous cytogenetic studies indicated that the most frequent alterations associated with this tumor entity affect chromosome 22. In this study, combined spectral karyotyping, fluorescence in situ hybridization, and array-based comparative genomic hybridization analyses of two proximal-type cases harboring a rearrangement involving 10q26 and 22q11 revealed that the 22q11 breakpoints were located in a 150-kb region containing the SMARCB1/INI1 gene, and that homozygous deletion of the gene was present in the tumor tissue. The SMARCB1/INI1 gene encodes for an invariant subunit of SWI/SNF chromatin remodeling complex and has been previously reported to act as a tumor suppressor gene frequently inactivated in infantile malignant rhabdoid tumors. We analyzed SMARCB1/INI1 gene status in nine additional epithelioid sarcoma cases (four proximal types and five conventional types) and altogether we identified deletions of SMARCB1/INI1 gene in 5 of 11 cases, all proximal types. We confirmed and further extended the number of cases with SMARCB1/INI1 inactivation to 6 of 11 cases, by real-time quantitative PCR analysis of mRNA expression and by SMARCB1/INI1 immunohistochemistry. Overall, these results point to SMARCB1/INI1 gene involvement in the genesis and/or progression of epithelioid sarcomas. Analysis of larger series of epithelioid sarcomas will be necessary to highlight putative clinically relevant features related to SMARCB1/INI1 inactivation.

Proximal-type epithelioid sarcoma in a 36-year-old man: closer immunoelectron-microscopic resemblance of the tumor cells to epithelial cells than to mesenchymal cells

Proximal-type epithelioid sarcoma (PES) is a rare neoplasm. We report a case of PES that arose in the perineal subcutis of a 36-year-old Japanese man who died within 4 months of the first clinical sign, probably due to massive pulmonary metastases. In the present study, we analyzed the tumor obtained at surgery, immunohistochemically, immunoelectron-microscopically and genetically. Although the tumor cells in the patient expressed both cytokeratin and vimentin immunohistochemically, they showed epithelial characteristics immunoelectron-microscopically because they had tonofilaments constructed of cytokeratin, not vimentin. In addition, the cytokeratins expressed on the tumor were glandular-type keratins. These findings indicate that PES may be a form of carcinoma in soft tissue. To ascertain the possible origin of the tumor, we compared the tumor immunohistochemically with fetal tissues. Although notochord and fetal peritoneal mesothelium were similar to the tumor antigenically, we could not confirm the specific origin of the tumor. Furthermore, the p53-WAF1 pathway did not contribute to tumorigenesis in the patient because the tumor had no mutation in exons 5-8 of the p53 gene and was immunohistochemically positive for WAF1.

"Proximal-type" and classic epithelioid sarcomas represent a clinicopathologic continuum: case report

We report a case of an epithelioid sarcoma that occurred in the right hand of a 14-year-old boy and had the "proximal-type" morphology and a complex, near-tetraploid karyotype. The tumor metastasized to the lungs, where the morphology was typical for the classic epithelioid sarcoma. Based on the morphologic and cytogenetic findings in this case, we suggest that the proximal-type and the classic epithelioid sarcomas are not distinct entities but represent a continuum.