Treatment of giant ancient pelvic schwannoma.

A 32-year-old patient presented with urinary retention and chronic constipation. Computerized tomography and magnetic resonance imaging showed a 10 x 11cm encapsulated tumor with cystic areas lying ventral to the sacrum. There was no evidence of invasion of bladder or rectum. At laparotomy, a 10 x 11 cm mass was found in the left pelvis. Final pathology revealed an ancient schwannoma. In most large series, 80% to 90% of the primary retroperitoneal tumors are malignant. Retroperitoneal schwannomas can be benign or malignant, roughly half of the reported cases showed malignancy. Benign schwannomas may arise along the course of any myelinated nerve, with the acoustic neuroma being the most frequent site. Immunostaining showed a strong expression of S-100 protein. The staining for this protein is helpful for differentiation of a benign schwannoma from a malignant peripheral nerve sheath tumor and from other benign spindle cell tumors. The treatment of choice for benign schwannomas is complete excision. Recurrence or persistence seems to be associated with incomplete resection, which occurred in 10% of the reported cases. After surgery, the patient had normal erection, normal micturition, and normal defecation but no symptoms of motor and sensory disturbances.