Biphasic Epithelial Predominant Synovial Sarcoma Presenting as Painful Thigh Mass.

Synovial sarcomas are soft tissue neoplasms mostly located in the lower extremities of young adults. A case of synovial sarcoma of the thigh in a 35-year-old male with the predominant epithelial component is reported. Microscopically the tumor showed variable-sized well-differentiated glands lined by the cuboidal cells with small foci of spindle cell component between glandular structures. Immunohistochemically glandular components showed positivity for the pan CK and EMA while CD99 and TLE1 were positive in both glandular and spindle cell components. This type of synovial sarcoma could be indistinguishable from metastatic adenocarcinoma and malignant adnexal tumor, thus, immunohistochemistry and molecular studies play an essential role in the exact diagnosis of this type of tumor.