Fine needle aspiration cytology of primary proximal-type epithelioid sarcoma of the perineum - A case report

Epithelioid sarcoma is a malignant soft tissue tumor of unknown histogenesis. We describe the cytologic findings in a case of primary proximal-type epithelioid sarcoma of the perineum and results of an immunofluorescence analysis of rhabdoid cells from this tumor. To the best of our knowledge, the 3-color immunofluorescence features of proximal type epithelioid sarcoma have never before been reported. Case An 8-cm-diameter mass with a 2.5-cm ulcer was found in the perineum of a 36-year-old man. After excision of the tumor, histopathologic examination of the specimen suggested a diagnosis of proximal-type epithelioid sarcoma. Fine needle aspiration cytology showed numerous rhabdoid cells with globular intracytoplasmic inclusions. A few isolated cells and polygonal cells were also observed in the smears. Three-color immunofluorescence analysis indicated that the intracytoplasmic inclusions in the rhabdoid cells were positive for cytokeratin, vimentin and CD34. The cytoplasmic staining pattern differed between rhabdoid and epithelioid sarcoma cells. Conclusion Immunofluorescent staining of rhabdoid cells from a primary perineal proximal-type epithelioid sarcoma revealed an uneven distribution of cytokeratin in intracytoplasmic inclusions, with the highest concentration at the periphery of the inclusions.