Synovial Sarcoma : Classification

Synovial sarcoma is composed of epithelial cells resembling carcinoma and spindle cells resembling fibrosarcoma. Based on the relative proportion of the two components and the degree of differentiation, synovial sarcomas can be classified into: 1) biphasic type (shown in this image), consisting of varying proportion of both epithelial and spindle cell components; 2) monophasic fibrous type (the most common type), composed purely of fibrosarcoma-like spindle cells; 3) monophasic epithelial type, composed exclusively or almost exclusively of epithelial component (epithelial-predominant; quite rare); and 4) poorly differentiated (round cell) type.