Synovial sarcoma of the vulva and vagina: a clinicopathologic and molecular genetic study of 4 cases.

Synovial sarcoma is a morphologically and genotypically distinctive soft tissue sarcoma with a strong predilection for young and middle aged adults and the deep soft tissues of the extremities. Rare cases of synovial sarcoma have been reported in a large variety of unusual sites, one of the least common being the female genital tract. We report 4 young women with synovial sarcoma involving the vulva (3 cases) and vagina (1 case). Two of the tumors were of the biphasic and 2 of the monophasic type; 3 of the tumors were poorly differentiated. The diagnosis in all the cases was supported by immunohistochemical findings and reverse transcription polymerase chain reaction and sequencing demonstration of SS18/SSX fusion transcripts. Two of the patients developed recurrent disease (1 dies of disease after 8 years) and 2 are currently disease-free.This study shows the importance of pathologists being aware of the rare occurrence of synovial sarcoma in the female genital tract, discusses the differential diagnosis with particular reference to this location, emphasizes the need for molecular genetic support in such cases, and reviews the sparse, earlier literature. Synovial sarcoma should be considered in the differential diagnosis of a vulvovaginal mesenchymal lesion, especially in a young female.