A Rare Case of Obturator Nerve Schwannoma Resembling Ovarian Malignancy: Learning from our Lesson

Abstract

Objective: Obturator nerve schwannoma is an uncommon pelvic tumor and, therefore, is usually overlooked as a probable diagnosis per initial, preoperative, radiologic evaluations. This leads to an unanticipated difficult intraoperative management in a narrow operative field, surrounded by vital organs. This report describes a patient with obturator nerve schwannoma who presented with a pelvic mass and underwent surgical evaluation for possible ovarian malignancy. Case presentation: A 58-year-old woman, presenting with asymptomatic right solid-cystic pelvic mass. Exploratory laparotomy, which was performed due to suspicion of ovarian cancer, revealed a 9-cm retroperitoneal mass located within the right obturator fossa, originating from the obturator nerve. Hysterectomy, bilateral salpingooophorectomy and enucleation of retroperitoneal mass were performed. The right obturator nerve was entirely preserved. Histopathological examination revealed a schwannoma. Postoperatively, the patient reported paresthesia at the medial aspect of the right thigh without weakness. No recurrence was detected at 6-month follow up. Conclusion: Although obturator nerve schwannoma is rare and often not diagnosed preoperatively, a thorough inspection of CT scan and MRI can potentially reveal a continuity with its anatomical origin. Subsequently, a needle biopsy can be performed to obtain a diagnosis. Laparoscopy is a safe therapeutic approach for schwannomas located within the obturator fossa.

Keywords

• Obturator nerve
• ovarian tumor
• pelvic mass
• schwannoma
• Siriraj Med J 2018;70: 455-458