Papillary renal cell carcinoma (pRCC) represents the second most common renal cell carcinoma. Diagnosis of pRCC has been challenged by emergence of several novel renal tumor entities with papillary morphology. Some of these have been found to constitute independent entities with specific molecular drivers, e.g. fumarate hydratase deficient renal cell carcinoma or TFE3 -rearranged or TFEB -altered RCC. Others are still considered emerging entities, such as papillary renal neoplasm with reverse polarity associated with KRAS mutations and biphasic hyalinizing psammomatous RCC associated with NF2 mutations. The recognition of these entities has changed the spectrum of “true” pRCC, and subclassification into type 1 and type 2 is no longer recommended. With the discovery of novel entities with specific diagnostic molecular traits, it is expected that the spectrum of pRCC is becoming increasingly narrow. This will potentially allow for a better prediction of prognosis and treatment response of pRCC. In this review we discuss recent developments in the diagnosis of renal tumors with papillary morphology, including emerging/provisional papillary renal tumor entities. The evolution of renal tumor classification has improved our understanding of biologic behavior and molecular background of pRCC with consequences on histopathological and molecular pathological approaches.
Lobo et al. (Wed,) studied this question.