Fig. 1: Hybrid oncocytic tumor in Birt–Hogg–Dubé (BHD) syndrome.
From: Do we need an updated classification of oncocytic renal tumors?
The patient had multifocal bilateral renal tumors, as well as multiple renal, liver, and lung cysts. A representative renal tumor is illustrated. A The tumor is non-encapsulated with solid growth; rare entrapped tubules are present at the periphery. Scattered cells with clear cytoplasm (“mosaic pattern”) can also be seen. B Higher magnification shows equivocal morphology between oncocytoma (mostly eosinophilic cells with round to oval nuclei) and chromophobe renal cell carcinoma (focal prominent cell membranes and nuclear halos). C Higher magnification of areas with “mosaic pattern” demonstrates scattered cells with clear cytoplasm, admixed with cells with eosinophilic cytoplasm. D Cytokeratin 7 is focally positive. E CD117 (KIT) is weakly positive only in focal areas. F Cathepsin K is diffusely positive.
