Importantly, many type 2 papillary RCC show significant variability in both their morphology and clinical behavior and, with growing use of molecular studies, are now recognized as distinct molecular or histologic types, such as FH-deficient RCC, MiT family translocation RCC, ALK-rearranged RCC, and acquired cystic-disease-associated RCC (ACD-RCC) [29]. This evidence concerns the gene FH and renal cell adenocarcinoma.