Primary adenocarcinoma of the rectovaginal septum arising in pregnancy in the absence of endometriosis

A case of primary adenocarcinoma of the rectovaginal septum (PARVS) is reported with clinical and pathological findings. A 37-year-old Caucasian woman with a history of sterility and small posterior leiomyoma, a few months after a cesarean section, was admitted because of vaginal spotting, abdominal pain and constipation. Her previous history did not reveal exposure to diethylstil bestrol (DES). Pelvic computed tomography showed a heterogeneous pelvic mass in the Douglas pouch, measuring 9 cm in diameter, located in the rectovaginal septum, involving the rectal and vaginal wall. Histological examination of neoplastic tissue revealed solid sheet structures, occasional tubular lumen, extensive necrotic areas and clear cells. The neoplastic elements showed immunoreactivity for Mullerian markers (cytokeratin 7, CA-125 and vimentin). Because, the present case of PARVS cannot be due to DES exposure, the clear appearance of the neoplastic elements could represent only one differentiation of Mullerian rests. Moreover, because no foci of endometriosis were identified in several sections of the neoplasm, uterine and cervical wall, and tissues nearby the neoplasm could represent a rare subtype of PARVS arising in the absence of endometriosis.