Abstract
The 2012 consensus conference of the International Society of Urological Pathology (ISUP) has formulated recommendations on classification, prognostic factors and staging as well as immunohistochemistry and molecular pathology of renal tumors. Agreement was reached on the recognition of five new tumor entities: tubulocystic renal cell carcinoma (RCC), acquired cystic kidney disease-associated RCC, clear cell (tubulo) papillary RCC, microphthalmia transcription factor family RCC, in particular t(6;11) RCC and hereditary leiomyomatosis-associated RCC. In addition three rare forms of carcinoma were considered as emerging or provisional entities: thyroid-like follicular RCC, succinate dehydrogenase B deficiency-associated RCC and anaplastic lymphoma kinase (ALK) translocation RCC. In the new ISUP Vancouver classification, modifications to the existing 2004 World Health Organization (WHO) specifications are also suggested. Tumor morphology, a differentiation between sarcomatoid and rhabdoid and tumor necrosis were emphasized as being significant prognostic parameters for RCC. The consensus ISUP grading system assigns clear cell and papillary RCCs to grades 1-3 due to nucleolar prominence and grade 4 is reserved for cases with extreme nuclear pleomorphism, sarcomatoid and/or rhabdoid differentiation. Furthermore, consensus guidelines were established for the preparation of samples. For example, agreement was also reached that renal sinus invasion is diagnosed when the tumor is in direct contact with the fatty tissue or loose connective tissue of the sinus (intrarenal peripelvic fat) or when endothelialized cavities within the renal sinus are invaded by the tumor, independent of the size. The importance of biomarkers for the diagnostics or prognosis of renal tumors was also emphasized and marker profiles were formulated for use in specific differential diagnostics.