<prompt> Hobnail pattern is seen in which type of RCCClear cellPapillaryChromophobeCollecting duct  <response>: Renal cell carcinoma Renal cancers are mostly sporadic, except for a 4 cases which appear familial Familial renal cancers are due to mutation of VHL and MET genes98 of all renal cancers sporadic and familial are due to VHL mutation encoded in chr3pMost common cause of familial papillary renal cell carcinoma rare disease is MET protooncogeneMost common risk factor for all renal cancers- TobaccoMost common type of renal cell carcinoma is clear cell carcinoma , which is followed by papillary carcinoma, chromophobe carcinoma and collecting duct carcinomaMost common type of renal cancer in patients who develop dialysis associated cystic disease - Papillary carcinomaVHL is a tumour suppressor gene. Mutation of both the VHL genes causes angiogenesis by increasing expression of hypoxia inducible factor-1 and cell growth by increasing expression of insulin like growth factor -1Renal cell carcinoma mostly affects the poles Microscopic findings:Classic clinical features of renal cell carcinoma - Costoveebral pain, palpable mass and hematuriaClear cell carcinoma -Cells with clear cytoplasm containing glycogen and lipids, delicate capillariesPapillary carcinoma - Papillary formations, foam cells in interstitium, psammoma bodiesCollecting duct carcinoma - irregular channels lined by atypical cells and show hobnail patternChromophobe cell carcinoma - cells with abundant cytoplasm impaing blue colour in Hales colloidal iron stain Ref: Robbins 8e p964 