Neurilemoma of the kidney.

Neurilemomas are neoplasms that originate from Schwann cells of the central and peripheral nervous systems. Thirteen case reports of neurilemomas involving the kidney have been described in the English literature. We report the fifth case of a neurilemoma within the renal sinus and review the previous cases of renal neurilemoma. This neoplasm is usually found incidentally. Presenting signs are nonspecific and radiographic features are highly variable. These factors make a preoperative diagnosis extremely difficult. Accurate identification relies heavily on detailed pathologic evaluation. Wide local excision is the treatment of choice, since malignancy is found in up to 30% of cases and there is a tendency for local recurrence and distant metastasis.