Papillary renal cell carcinoma within an oncocytoma: a rare Case report

Renal oncocytoma is the most common benign renal tumor, accounting for 3% to 9% of all primary renal neoplasms of the kidney . It is derived from intercalated cells . papillary renal cell carcinoma(PRCC) is the second most common of renal cell carcinoma , comprises 10-15 % of all renal cell carcinomas. It is believed to derive from proximal tubular epithelium.As these two entities have different cell ori gin, the existence of a PRCC within an oncocytoma is extremely unusual. These tumor is challenging for urologists, pathologists and oncologists.An 68-year-old woman was referred to our hospital after detection of a renal mass on abdominal ultrasonography. Her physical examination was unremarkable, and laboratory findings were within normal values. Computed tomography revealed a 26 mm mass in the lower pole of her right kidney. Right radical nephrectomy was carried out. Macroscopical examination revealed a well-circumscribed solid lesion in the renal parenchyma, yellowish/tan in color. Light microscopy showed, tumor composed of papillary renal cell carcinoma and oncocytoma .Although oncocytoma and RCC are separate entities, they can coexist in the same kidney. This case shows us that although very rare, renal oncocytoma may contain malignant tumour, such as RCC. Therefore, even if the radiological screening strongly suggests that the tumour is oncocytoma, this rare entity should also be kept in mind and sectioning and examination is recommended to exclude the presence of an associated malignancy.

کلیدواژه ها:

Collision tumor ، Oncocytoma ، Papillary renal cell carcinoma