Incidentally Discovered Ovarian Cancer Combined With Obturator Nerve Schwannoma: A Rare Case Report

A rare coexistence of high‐grade serous ovarian cancer and an obturator nerve schwannoma presented as a node‐like pelvic sidewall mass. A 50‐year‐old woman had progressive abdominal distension, CA‐125 1534 U/mL (reference range 0–35 U/mL), and computed tomography (CT) showing ovarian cancer with a left sidewall mass interpreted as nodal disease. After three cycles of paclitaxel–carboplatin, the ovarian disease regressed while the sidewall mass was unchanged. Because a percutaneous route was likely to traverse major vessels and open cytoreduction was planned, biopsy was deferred. At laparotomy, a well‐circumscribed lesion centered on the obturator canal was dissected along the epineurial plane and intracapsularly enucleated, preserving the obturator nerve and its fascicles. Pathology showed schwannoma (spindle‐cell fascicles with Verocay bodies; diffuse S‐100 positivity; no epithelial markers). Posttreatment CT met the Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 for complete response; the patient received maintenance olaparib plus bevacizumab and, at 32‐month follow‐up, had no evidence of recurrence with intact adductor function. This case suggests that, during ovarian cancer cytoreduction, a stable, well‐circumscribed sidewall mass on CT—particularly along the obturator canal—should raise suspicion for a neurogenic tumor; when biopsy access is unsafe and open surgery is planned, nerve‐sparing enucleation is an appropriate management option.