Renal oncocytoma with hyaline globules: cytologic diagnosis by guided fine needle aspiration, a case report.

Renal oncocytomas are rare renal parenchymal neoplasms which have a good prognosis. An accurate pre-operative diagnosis by guided fine needle aspiration cytology helps to plan a more conservative surgery. Cytologic findings in a case of renal oncocytoma are presented. Smears showed polygonal or rounded cells in groups and acinar pattern having a well-defined, granular, eosinophilic cytoplasm, and round regular nuclei displaying very little pleomorphism. Intra and extracellular hyaline material staining pink with May Grunwald Giemsa stain were seen. The resected specimen showed the characteristic findings of oncocytoma. Renal oncocytoma has to be distinguished from granular renal cell carcinoma (RCC) and chromophobe cell carcinoma, because of the markedly different prognosis.