Proximal-type epithelioid sarcoma in the pelvic soft tissues

A case of proximal-type epithelioid sarcoma arising in the pelvic soft tissues of a 46-year-old man is presented. The tumor showed a predominantly epithelioid component with rhabdoid features, cordlike arrangement, small nests, abundant eosinophilic cytoplasm containing intracytoplasmic, paranuclear, hyaline-like globules, large vesicular nuclei, and prominent nucleoli. There were foci with alveolar arrangement and a spindle-cell proliferation. The tumor cells were positive for cytokeratin CAM5.2, vimentin, epithelial membrane antigen, and CD34. Flow cytometry showed a diploid DNA content with high S-phase fraction. The patient had pelvic lymph-node metastases. He died of the disease 5 months after diagnosis. It is important to include proximal-type epithelioid sarcoma in the differential diagnosis of pelvic tumors.