Variants and Variations in Epithelial Renal Cell Tumors in Adults: The Pathologist's Point of View

Abstract

Abstract Context and Objectives The Vancouver consensus conference of the International Society of Urological Pathology provided the foundation for the 2016 World Health Organization (WHO) classification of the renal tumors. The aim of this contribution is to review some of the major changes and additions to tumor variants and variations in the current classification of the renal cell neoplasms in adults. Evidence acquisition and Evidence synthesis Several publications report no recurrence or metastasis in patients with multilocular cystic renal cell carcinoma (RCC). Multilocular cystic renal neoplasm of low malignant potential is now the term recommended by the WHO for this lesion. A similar recommendation has been made in the current literature for hybrid oncocytic/chromophobe tumors (ie, oncocytic neoplasia of uncertain malignant potential) and for clear cell papillary renal cell carcinoma (ie, neoplasm of low malignant potential). Some of the latter tumors were referred to as renal angioadenomatous tumors. Papillary RCC has traditionally been subdivided into type 1 and type 2 papillary RCCs. Recent molecular studies suggest that type 2 papillary RCCs may not constitute a single well-defined entity. There are newly recognized epithelial renal tumor entities in the 2016 WHO classification such as succinate dehydrogenase-deficient RCC. Conclusions and Patient summary There are some additional variations in the tumor types that are not included in the WHO classification, however, worth knowing, such as clear cell RCC with hemangioblastoma-like features and unclassified RCC with medullary phenotype.