Renal Oncocytoma

Abstract

Review of the Mayo Clinic [Rochester, Minnesota, USA] tissue registry for 1950-1979 identified 90 cases of pure, well differentiated eosinophilic granular cell renal tumors. The clinical, laboratory, pathologic and survival features of these patients were analyzed. Of these tumors 59% were discovered incidentally during an examination for other problems; 91% were confined within the renal capsule, with no evidence of local invasion. Sixty-two patients had grade 1 and 28 had grade 2 tumors. None of the patients with grade 1 tumors developed metastases. Of the patients with grade 2 tumors 4 died of metastatic disease. Survival curves show no difference in survival between patients with these renal tumors, and an age and sex matched cohort. If the term renal oncocytoma is used to signify a very well differentiated (grade 1) eosinophilic granular cell renal parenchymal tumor, then renal oncocytomas apparently are nonaggressive tumors with a highly favorable prognosis.