Renal Oncocytoma and Pelvic Urothelial Carcinoma in a Nephrectomy Specimen of a 72-Year-Old Patient.

We present the case of a 72-year-old gentleman who presented with a left renal mass. His Computerized Tomography Angiogram showed an 11.8 x 11.3 cm mass involving the upper pole of the left kidney. The mass showed a central stellate scar. There was no locoregional lymphadenopathy. His radical nephrectomy specimen was received in our lab. Sectioning showed a large tumor in the upper pole with a central stellate scar. Microscopically, it showed sheets and nests of round cells with eosinophilic cytoplasm and round nuclei. It was positive for CD117 and negative for CK7. The sections from the renal pelvis showed a urothelial carcinoma arising from the urothelial lining and infiltrating the muscular wall of the renal pelvis. This tumor was positive for CK7 and GATA3. In this case report, we present a rare collision tumor of renal oncocytoma and pelvic urothelial carcinoma.