LAUSR

Casestudy: High-grade uterine sarcomas are rare mesenchymal tumors in which the underlying genetics of many have been recently elucidated. BCOR internal tandem duplications are present in a subset of high-grade uterine sarcomas. We report a diagnostically challenging case of a high-grade uterine sarcoma with a BCOR internal tandem duplication presenting with total uterine inversion. The case is that of a 24 year old G0P0 female with a four month history of intermittent diffuse abdominal pain and abnormal uterine bleeding. Pelvic examination revealed a mass protruding to the hymenal ring. The patient was suspected of having a prolapsed fibroid through the cervix, and a myomectomy was planned. During the procedure, total uterine inversion was noted as a result of a submucosal mass emanating from the uterine apex. The mass was removed off a broad base using sharp dissection, and the uterus was reverted in a subsequent procedure. Grossly, the mass was polypoid, rubbery, and measured 7 cm in greatest dimension. It was grey-white to red-brown, variegated, and fibrotic with focal hemorrhagic areas. Histologically, the neoplasm had variable cellularity with spindle cells and a myxoid background. There was diffuse mild to moderate cytologic atypia and areas of increased mitotic activity. Tongue-like growth was present at the interface of the tumor with the normal myometrium. The neoplastic cells showed strong immunoreactivity for cyclin D1, BCOR, and TRK. There was focal immunoreactivity for CD10, and ALK was negative. Next-generation sequencing was performed and demonstrated an insertion into the BCOR gene, consistent with a diagnosis of high- grade uterine sarcoma with BCOR internal tandem duplication. In conclusion, we report an interesting presentation of a high-grade uterine sarcoma with BCOR internal tandem duplication causing total uterine inversion. The morphologic features and immunohistochemical profile suggested the possibility of the entity, and next generation sequencing confirmed the diagnosis.