RENAL ONCOCYTOMA - CLINICAL AND BIOLOGICAL CORRELATES

We treated 31 patients with renal oncocytoma. Renal cell carcinoma was found existing separately within the same or contralateral kidney in 10 patients (32%). Followup of 29 patients revealed 24 alive with no e vidence of disease and 1 alive with recurrent oncocytoma, while 1 with coexistent tumors died of progressive renal cell carcinoma and 3 tumo r-free patients died of unrelated diseases. Quantitative deoxyribonucl eic acid analysis was performed on cell suspensions of fresh tumor by flow cytometry or by image cytometry on touch preparations from frozen tissue in 16 patients with renal oncocytoma. Ploidy analysis revealed all oncocytomes to be diploid. Frozen tissue immunohistology was perf ormed using murine monoclonal antibody against human HLA-A, B and C (c lass I) antigens with the avidin-biotin peroxidase technique in 11 pat ients with renal oncocytoma. Ten oncocytomas did not express these sel f-recognition antigens and 1 was only weakly positive for antigen expr ession. In contrast, renal cell carcinomas strongly expressed HLA clas s I antigens. The high incidence of coexistence of renal oncocytoma an d renal cell carcinoma has important clinical implications. Loss of HL A class I antigen expression by renal oncocytomas may provide an addit ional method for differentiating this lesion from renal cell carcinoma .