The rectovaginal septum is a rare location for gastrointestinal stromal tumors (GIST) to occur. When such is the case, the question arises as to whether the lesion, which is morphologically and immunophenotypically identical to its gastrointestinal counterpart, should be referred to as an extragastrointestinal stromal tumor (EGIST). A 77-year-old, gravida 4, para 4004 post-menopausal female with an unremarkable gynecologic history presented with brown vaginal discharge. On examination, a 4 to 5-cm nodule was palpated along the rectovaginal septum. Ultrasound revealed a 4.8-cm circumscribed, solid mass with internal blood flow located posterior and inferior to the cervix. At laparoscopy, the uterus and adnexae were deemed to be normal for age, without gross pathologic abnormalities. The nodule was resected in an enucleation procedure; subsequent histopathologic examination revealed a low-grade, spindled cell neoplasm with diffuse immunoreactivity for CD117 (cKit) and DOG1, diagnostic of GIST. Further molecular testing elucidated a mutation in exon 9 of the Kit gene. A decision was made by the patient for close observation; there is no clinical or radiographic evidence of recurrence one year after initial diagnosis.
Keywords: gastrointestinal stromal tumor; pathology; rectovaginal septum.