Malignant peripheral nerve sheath tumor of the renal pelvis.

Malignant peripheral nerve sheath tumors (MPNST) of the urothelial collecting system are rare. These tumors contain both malignant epithelial and sarcomatous components. Metastatic spread of MPNST is common, however, metastases to the kidney and perirenal tissues are rare. There are only 4 cases reported of MPNST of the kidney. We report a rare case of MPNST arising from the submucosa of the renal pelvis.