Flow cytometric analysis of cellular deoxyribonucleic acid content of nine renal oncocytomas

The cellular deoxyribonucleic acid content of formalin-fixed, paraffin-embedded tissue from nine renal oncocytomas was determined using an Epics-C flow cytometer. The tissues were all from surgical specimens, and all neoplasms met stringent light and electron microscopic criteria for the diagnosis of oncocytoma. Thirteen samples of pure tumor, 5 of tumor and normal kidney, and 3 of normal kidney alone were analyzed. All oncocytomas had single, sharp G1 peaks with no evidence of aneuploidy, and this peak was similar to that of normal renal parenchyma. This was true even for three oncocytomas that had multiple major chromosomal anomalies on karyotyping. These data support the concept that renal oncocytomas are euploid neoplasms, consistent with their benign biologic behavior. The apparent discrepancy between the results of flow cytometry and karyotyping is discussed.