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.