Epithelioid sarcoma: Report of two cases diagnosed by fine-needle aspiration biopsy with immunocytochemical correlation

Epithelioid sarcoma (ES) is an aggressive soft-tissue malignant minor gener ally arising in the distal extremities of young adults. The microscopic dia gnosis of ES is often difficult because of its rarity and its possible conf usion with other malignant tumors or even with benign granulomatous process es, Two cases of ES and a recurrence of one of these rumors, diagnosed by f ine-needle aspiration biopsy (FNAB), are reported. Cytologic smears were qu ite similar in both cases including the relapse, showing single or loosely arranged groups of medium to large atypical cells. Single cells had well-de fined eosinophilic cytoplasms and one or more atypical, eccentrically locat ed nuclei, resulting in a plasmacytoid appearance. Nuclei had fine granular chromatin and one or two large nucleoli. The cells sometimes palisaded alo ng the edges of necrotic material. The immunocytochemical stains showed dif fuse cytoplasmic positivity for cytokeratins (CAM 5.2) and both cytoplasmic and cell membrane positivity for vimentin, while S-100 protein and HMB 45 immunostaining were negative, thus supporting the cytological diagnosis of ES, which was subsequently proven on the surgical samples. (C) 1999 Wiley-L iss, Inc.