Epithelioid sarcoma: report of two cases diagnosed by fine-needle aspiration biopsy with immunocytochemical...

Epithelioid sarcoma (ES) is an aggressive soft-tissue malignant tumor generally arising in the distal extremities of young adults. The microscopic diagnosis of ES is often difficult because of its rarity and its possible confusion with other malignant tumors or even with benign granulomatous processes. Two cases of ES and a recurrence of one of these tumors, diagnosed by fine-needle aspiration biopsy (FNAB), are reported. Cytologic smears were quite similar in both cases including the relapse, showing single or loosely arranged groups of medium to large atypical cells. Single cells had well-defined eosinophilic cytoplasms and one or more atypical, eccentrically located nuclei, resulting in a plasmacytoid appearance. Nuclei had fine granular chromatin and one or two large nucleoli. The cells sometimes palisaded along the edges of necrotic material. The immunocytochemical stains showed diffuse 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. Diagn. Cytopathol. 1999;21:405-408.