The classification working group of the International Society of Urological Pathology consensus conference on renal
neoplasia was in charge of making recommendations regarding additions and changes to the current World Health Organization Classification of Renal
Tumors (2004). Members of the group performed an exhaustive literature review, assessed the results of the preconference survey and participated in the consensus conference discussion and polling activities. On the basis of the above inputs, there was consensus that 5 entities should be recognized as new distinct epithelial
tumors within the classification system: tubulocystic
renal cell carcinoma (RCC), acquired cystic disease-associated RCC, clear cell (tubulo) papillary RCC, the MiT family translocation RCCs (in particular t(6;11) RCC), and hereditary
leiomyomatosis RCC syndrome-associated RCC. In addition, there are 3 rare
carcinomas that were considered as emerging or provisional new entities: thyroid-like follicular RCC;
succinate dehydrogenase B deficiency-associated RCC; and ALK translocation RCC. Further reports of these entities are required to better understand the nature and behavior of these highly unusual
tumors. There were a number of new concepts and suggested modifications to the existing World Health Organization 2004 categories. Within the clear cell RCC group, it was agreed upon that multicystic clear cell RCC is best considered as a
neoplasm of low malignant potential. There was agreement that subtyping of papillary RCC is of value and that the oncocytic variant of papillary RCC should not be considered as a distinct entity. The hybrid oncocytic chromophobe
tumor, which is an indolent
tumor that occurs in 3 settings, namely
Birt-Hogg-Dubé Syndrome, renal oncocytosis, and as a sporadic
neoplasm, was placed, for the time being, within the chromophobe RCC category. Recent advances related to
collecting duct carcinoma, renal
medullary carcinoma, and mucinous spindle cell and tubular RCC were elucidated. Outside of the epithelial category, advances in our understanding of
angiomyolipoma, including the epithelioid and epithelial cystic variants, were considered. In addition, the apparent relationship between cystic nephroma and mixed epithelial and stromal
tumor was discussed, with the consensus that these
tumors form a spectrum of
neoplasia. Finally, it was thought that the
synovial sarcoma should be removed from the mixed epithelial and mesenchymal category and placed within the
sarcoma group. The new classification is to be referred to as the International Society of Urological Pathology Vancouver Classification of Renal
Neoplasia.