Coexistence of multiple clear cell papillary renal cell carcinoma with renal oncocytoma: a case report.

Clear cell papillary renal cell carcinoma (CCPRCC) is a new entity, previously known as unclassified renal cell carcinoma, and initiallly identified in patients suffering of end-stage kidney failure. It is extremely rare to see this new entity associated with others renal malignant lesions. Case presentation: The authors report a case of a female 65-year-old suffering from end-stage kidney failure for 10 years, who presented with a double left renal tumor, composed by an oncocytoma associated to multiple CCPRCC, a very rare entity. A radical left nephrectomy was realized by lumbotomy, with an uneventful postoperative course. Histological examination was challenging. Immunohistological examination showed diffuse positivity of cytokertain 7. No local recurrence nor metastatic progression were found during the 12 months of follow-up. Clinical discussion: CCPRCC, is a new entity, previously known as the unclassified rena cell carcinoma, is a malignant renal tumor, initially reported in patients at end-stage kidney failure. Oncocytoma is a well-known rare benign renal tumor. The association of both is rare, and should be kept in mind, especially when scanoguided diagnosis biopsy is realized. Histopathological confirmation may be challenging, given the recent identification of CCPRCC. The nuclei disposal toward the luminal surface is a characteristic pathological landmark of CCPRCC. Immunohistopathological examination is of great help, showing a distinctive profile: diffuse staining for cytokertain 7 and carbonic anhydrase IX. Conclusion: CCPRCC is a new malignant pathological entity in renal tumors. It can be associated with other benign renal lesions. This should be taken into consideration while histopathological examination, mainly of scanoguided biopsy cores.