Epithelioid sarcoma is a rare tumor with characteristic morphologic and immunohistochemical features. It can be confused histologically and cytologically with a variety of benign and malignant lesions, including a granulomatous process, synovial sarcoma, melanoma, squamous cell carcinoma, and adenocarcinoma. The objective of this study was to define the cytologic features of this rare tumor.
The cytologic features of nine histologically confirmed epithelioid sarcomas were analyzed. The criteria evaluated included cell size and shape, cell borders, cluster organization, cytoplasmic characteristics, nuclear and nucleolar features, and background characteristics.
In most cases, single, dispersed cells represented the predominant pattern, with only a few small clusters present. The cells were mostly round with interspersed spindle cells and mild to moderate pleomorphism. The nuclei were large and eccentrically located, with a plasmacytoid appearance. A pale zone in the perinuclear area was evident in three of nine cases. Well-defined cell borders with intercellular spaces between malignant cells were observed in eight cases. In three cases, a granuloma-like structure was identified. In two cases, the cells were mostly spindle and showed greater cellular pleomorphism.
Epithelioid sarcoma is an uncommon tumor with a wide range of differential diagnoses, especially in cytology specimens. Awareness of its existence and knowledge of its cytologic features are important for a correct diagnosis.