Calcifying Synovial Sarcoma

ABSTRACT

A case of calcifying synovial sarcoma, occuring in the deep muscle fascia of the left thigh is reported. The presence of extensive calcification in synovial sarcoma is a favorable sign for prognosis. The patient was a 31-year-old female. The tumor mass had been present for 3 years, accompanying local tenderness. X-ray revealed a soft tissue tumor with central calcification, which was located between the adductor magnus and brevis of the left thigh. The tumor size was 7 x 5.5 cm. There was no connection with the knee joint or the femur. Grossly, the tumor was a relatively well circumscribed hard tumor with massive calcification. Microscopically, the tumor was composed of predominantly spindle cells with accompanying hyalinization, numerous spherical concretions and ossification. The epithelial component was not clearly noted. Mitotic figures were rarely noted in the densely cellular area. Immunohistochemical staining for EMA, S-100, vimentin, and carcinoembryonic antigen was negative while vimentin and cytokeratin were weakly and focally positive. EM study revealed multiple desmosome-like calcification intercellular junctions with a slit-like lumen and an incomplete basal lamina, which suggest that tumor show these cells were undergoing epithelia] differentiation. Above evidence suggest that this tumor is a synovial sarcoma associated with a large area of calcification, a so called calcifying synovial sarcoma. No recurrence was noted in one and half years of follow up.