Synovial sarcoma diagnosed by fine-needle aspiration biopsy. A case report.

The cytologic findings of a synovial sarcoma are described. A 60 year old male had felt a slowly growing tumor in his right sole for three years. From the first fine-needle aspiration biopsy a fibrosarcoma or other mesenchymal tumor was suggested; but the second biopsy showed both fibrosarcoma and mesothelial-like cells in contact with each other, and the diagnosis of synovial sarcoma was made. Histologic and electron microscopic sections confirmed the diagnosis. In the differential diagnosis of this case, fibrosarcoma and other malignant mesenchymal tumors were considered. The applicability of fine-needle aspiration biopsy in mesenchymal lesions is discussed.