Fine needle aspiration cytology of clear cell sarcoma. Report of a case with immunocytochemical, immunohistochemical and ultrastructural studies.

Cytologic findings of clear cell sarcoma obtained by fine needle aspiration (FNA) of a tumor are described. The tumor probably originated in the retroperitoneal tissue, and the diagnosis was confirmed histologically by open biopsy. Percutaneous needle aspirates of the intraabdominal tumor and touch preparations obtained from the open biopsy specimen revealed numerous atypical cells with an extremely hyperchromatic nucleus, prominent nucleoli and clear cytoplasm. The cytoplasm was rich in glycogen. The immunocytochemical technique demonstrated S-100 protein and neuron-specific enolase in the cytoplasm, both of which were exhibited also in the histologic specimen. Clear cell sarcoma is a rare tumor of soft tissue, and to our knowledge, detailed cytologic appearances of this tumor obtained by FNA have not been reported. In addition, the present tumor was unique in location. It is possible to diagnose clear cell sarcoma accurately on an FNA cytologic specimen if the periodic acid-Schiff stain and immunocytochemical technique are utilized in addition to the routine Papanicolaou method.