Poorly differentiated synovial sarcoma. A light and electron microscopic study.

Few studies of the ultrastructural features of synovial sarcoma have appeared in the literature. The case under study represented a poorly differentiated synovial sarcoma with a predominant fibrosarcomatous component and a few areas with epithelioid and pseudoacinar patterns. Ultrastructurally, the cellular elements of the varied histologic patterns were similar. Basement membranes and desmosomes were absent, and the cell surfaces facing the acinar lumen exhibited multiple microvilli. It appears from a comparison of our studies with the previous reports that the fine structure of this tumor varies according to the degree of histologic differentiation.