Botryoid-type pleomorphic rhabdomyosarcoma of the renal pelvis in an adult. A rare case report and review of the literature.

Rhabdomyosarcoma of the renal pelvis is an extremely rare lesion for which only two reports are available. Here, we report another case of botryoid-type pleomorphic rhabdomyosarcoma in the renal pelvis. The tumor produced mild hydroureteronephrosis and right nephrectomy was performed after the needle aspiration cytology revealed abnormal epithelial clusters. The surgical specimen disclosed a polypoid mass attached to the wall of the lower pole of the renal pelvis. Light microscopy examination revealed a large polypoid tumor protruding from the inner surface of the renal pelvis with intact surface urothelium. Immunohistochemical stains for actin, myoglobin, and vimentin were positive. Although rhabdomyosarcoma has formerly been reported to occur at the renal pelvis, to our knowledge, this is the first case of renal pelvis botryoid-type pleomorphic rhabdomyosarcoma diagnosed by light microscopy and immunohistochemical stains.