[Pathological diagnosis of renal tumors: up to date]

Renal cell carcinoma (RCC) is composed of heterogenous histological types, with different clinical features and molecular biological characteristics. The "General Rule for Clinical and Pathological Studies on RCC" was revised in 2011, according to the World Health Organization system (WHO) (2004). Although most RCC is clear cell RCC (approximately 70-80% of RCC), papillary and chromophobe RCCs are occasionally encountered (approximately 10 and 5%, respectively). Collecting duct carcinoma is a rare and highly aggressive adenocarcinoma derived from the collecting duct. Additionally, several histological types have been introduced, and "granular RCC" has been omitted as a diagnostic term. For precise diagnosis, careful gross and histological evaluations are required along with immunohistochemical and molecular biological analyses. Additionally, novel histological types have recently been emerging, i.e., 6p21 translocation-associated RCC, dialysis-associated RCC, and tubulocystic carcinoma. Furthermore, mimics of RCC are always considered as differential diagnostic candidates, i.e., metanephric adenoma, epithelioid angiomyolipoma, juxtaglomerular cell tumor, and carcinoid tumor.