Aspiration biopsy cytology of renal oncocytoma

The fine needle aspiration biopsy findings in four cases of renal oncocytomas were reviewed. The cytologic smears contained many large, well-demarcated, eosinophilic cells with prominent nucleoli. Some of the cells were binucleated. The findings in these cases indicate that renal oncocytoma may be suggested preoperatively on the bases of renal angiography and aspiration biopsy cytology. The differential diagnosis between renal adenocarcinoma and carcinomas with oncocytic differentiation is discussed.