[Schwannoma of the obturatorius nerve as differential diagnosis in cystic adnexa tumors].

We report on a case of benign retroperitoneal schwannoma involving the obturator nerve. Discussing the difficulties of diagnosis and treatment the following became clear: 1.) Clinical examination, ultrasound and computed tomography are not helpful to differentiate a retroperitoneal schwannoma from a cystic ovarian tumour; this problem can perhaps be overcome by MR imaging. 2.) The diagnosis should be borne in mind in cases of retroperitoneal tumours of unclear origin. Appropriate surgery is necessary to avoid nerve damage and paralysis.