Retroperitoneal Schwannoma Mimicking Ovarian Mass: A Rare Case Report

Schwannomas are benign soft-tissue tumors originating from Schwann cells in the myelin sheath of peripheral nerves as well as from nerve roots. Retroperitoneal schwannomas, accounting for 1%–3% of all schwannomas, are rare and often mimic gynecological malignancies, posing diagnostic challenges. This report highlights a case of a 40-year-old female presenting with abdominal pain, heavy menstrual bleeding, dysmenorrhea, and passage of clots. Clinical examination and ultrasonography revealed a right ovarian mass (10.2 cm × 6.3 cm), a left ovarian cyst (3.7 cm × 2.7 cm), and an intramural fibroid of size 1.9 cm (International federation of Gynecology and Obstetrics [FIGO] type 3). Tumor markers (CA-125, CEA, and CA19.9) were within normal limits, ruling out typical ovarian malignancies. Other tumor markers human chorionic gonadotropin and Inhibin had not done. The patient underwent a panhysterectomy with bilateral salpingectomy with excision of the retroperitoneal mass. Intraoperatively, the operating surgeon had sent a specimen of retroperitoneal mass for frozen section examination. A gross examination revealed a firm mass with degenerative changes. Panhysterectomy specimen on histopathology revealed simple endometrial hyperplasia, an intramural leiomyoma, and chronic cervicitis with an inflammatory cervical polyp and normal bilateral fallopian tube. Excised retroperitoneal mass on histopathology identified an ancient schwannoma with focal nuclear atypia. Immunohistochemistry confirmed the schwannoma diagnosis, with positive SOX10 and S100, and negative SMA and CD34. Concurrent intramural leiomyoma and normal fallopian tube histology were also noted. Retroperitoneal schwannomas, particularly of ancient type, often mimic ovarian malignancies due to overlapping symptoms, demanding comprehensive diagnostic workups. Imaging, histopathology, and immunohistochemistry are pivotal for distinguishing schwannomas from gynecological malignancies, ensuring accurate diagnosis and management. This case highlights the importance of considering rare differential diagnoses in patients with complex presentations. Surgical excision remains essential for definitive diagnosis and symptom resolution, with histopathological evaluation key to identifying prime and concurrent pathologies, in cases of overlapping gynecological and retroperitoneal masses.