Hobnail pattern is seen in which type of RCC

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 genes*98% of all renal cancers (sporadic and familial) are due to VHL mutation encoded in chr3p*Most common cause of familial papillary renal cell carcinoma (rare disease) is MET protooncogene*Most common risk factor for all renal cancers- Tobacco*Most common type of renal cell carcinoma is clear cell carcinoma , which is followed by papillary carcinoma, chromophobe carcinoma and collecting duct carcinoma*Most common type of renal cancer in patients who develop dialysis associated cystic disease - Papillary carcinoma*VHL 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 -1)*Renal cell carcinoma mostly affects the poles Microscopic findings:*Classic clinical features of renal cell carcinoma - Costoveebral pain, palpable mass and hematuria*Clear cell carcinoma -Cells with clear cytoplasm containing glycogen and lipids, delicate capillaries*Papillary carcinoma - Papillary formations, foam cells in interstitium, psammoma bodies*Collecting duct carcinoma - irregular channels lined by atypical cells and show hobnail pattern*Chromophobe cell carcinoma - cells with abundant cytoplasm impaing blue colour in Hale's colloidal iron stain (Ref: Robbins 8/e p964)