Evaluation of perinephric, retroperitoneal schwannomas: case report and review of the literature.

Schwannomas are tumors arising from the nerve sheath. Because of their infrequent occurrence, nonspecific symptoms, and lack of distinguishing radiologic features, schwannomas are most often diagnosed histologically after surgical excision. We report herein a case of a perinephric, retroperitoneal schwannoma which, after evaluation by computed tomography, magnetic resonance, and angiography, appeared to be a renal cell carcinoma arising from the left kidney. The diagnosis of benign retroperitoneal schwannoma was made by histologic examination and immunohistochemical staining of the excised mass. A practical algorithm for perinephric, retroperitoneal schwannomas is proposed.