Mimicker of Renal Cell Carcinoma- A Case Report

Abstract

Oncocytoma is a rare epithelial tumour composed of oncocytes which are epithelial cells with excessive amount of mitochondria. The tumour is most often benign, and diagnosis can be made on the basis of histopathological examination. Here, the authors present a 64-year-old female patient, with complaints of abdominal discomfort and flank pain, along with history of loss of weight and appetite for one month. Radiology showed a left renal mass of measuring 9×7×4.5 cm involving the upper and middle pole suggestive of malignancy. Following which radical nephrectomy was done. Examination of gross specimen showed a fairly circumscribed brownish lesion in the upper and middle pole of left kidney measuring 8.8×7×4.5 cm with a central scar. There was no evidence of hilar and perirenal fat invasion. Histology showed sheets of large polygonal eosinophilic cells with centrally placed nucleus. The differentials were eosinophilic variant of clear cell renal cell carcinoma, chromophobe renal cell carcinoma and oncocytoma. A panel of Immunohistochemical (IHC) markers was performed for further categorisation and the lesional cells were positive for CD 117 and negative for CD 7 and CD 10. This ruled out the differentials and confirmed oncocytoma, thus ruling out the necessity for chemotherapy.