Benign schwannoma of the pelvic retroperitoneum. Report of a case and review of the literature

Benign schwannoma is a tumor arising from Schwann cells (forming the neural sheath of peripheral nerves). The retroperitoneal location is unusual (0.5-5% of cases). Most common locations are cranial nerves (especially the 8th pair) and, in peripheral nerve system the neck, mediastinum and extremities. To this date the known cases of benign retroperitoneal schwannoma are about 60, of which less than 20 in the pelvis. The low frequency of this tumor and the lack of specific instrumental signs and objective symptoms (since it develops in a deep and broad region as retroperitoneum) make presurgical diagnosis very difficult. It can be confirmed only during surgery and definitive histological examination. The information provided by ultrasonography, CT and MR help to limit diagnostic hypothesis, but they don't show any pathognomonic images. The resection of this tumor is the appropriate treatment, even though it is really a complex one. Prognosis is quite good since post-surgical recurrences are unusual. If they appear is probably because excision wasn't radical. Complete resection is the best treatment for retroperitoneal pelvic schwannoma and today it can be performed also by laparoscopy. Partial resection can be used when the mass is strongly connected to essential organs in order to prevent iatrogenic harms (neural deficit, vessel lesions); this may occur in 10% of cases. This paper describes a benign schwannoma with pelvic retroperitoneal location, incidentally discovered during a routine gynecological check up. The purpose of this study is to review current therapeutic and diagnostic techniques in retroperitoneal pelvic schwannoma (including a review of current literature) and to identify th problems that can be encountered in the differential diagnosis of this unusual disease from other neoplasms occurring in the same place.