Abstract

Epithelioid sarcomas are rare, high-grade mesenchymal tumors. Clinically they tend to arise on the extremities of adults as papules or nodules that may ulcerate. On histopathology they have a biphasic appearance with a transition between epithelioid and spindled cells. Traditionally, epithelioid sarcomas stain positive for pancytokeratin, vimentin, EMA, and CD34. Negative markers include p63 and high molecular weight keratin. Importantly, this entity exhibits loss of INI-1 expression which can help confirm the diagnosis. Here we report a case of epithelioid sarcoma masquerading as a squamous cell carcinoma. A 27-year-old female presented to the hospital with a solitary, painful 2.5cm x 3.0cm ulcerated plaque with violaceous border on her right distal leg present for six months. Initial punch biopsy revealed an atypical spindle cell proliferation positive for pancytokeratin, p53, CD10, and vimentin, with S100, smooth muscle myosin, and PAS negative. Although initial pathology favored diagnosis of SCC, clinically we were suspicious of this diagnosis in a young, otherwise healthy young woman. Therefore, the patient was seen in the dermatology clinic for further investigation. Incisional biopsy was performed which demonstrated an atypical epithelioid and spindle cell neoplasm filling the dermis with associated necrosis. The lesion was positive for CD34 and pancytokeratin with negative INI-1 staining. A diagnosis of epithelioid sarcoma was made, and the patient was referred to surgical oncology for further evaluation and treatment. This case demonstrates the importance of high suspicion and clinical pathologic correlation for diagnosing epithelioid sarcoma. Often, the lesion may be mistaken for SCC, pyoderma gangrenosum, or even a benign entity, which can result in insufficient treatment. In such instances, consulting a trained dermatopathologist and using immunohistochemical panel is indicated to differentiate this tumor from its mimickers.

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