DOG1, cyclin D1, CK7, CD117 and vimentin are useful immunohistochemical markers in distinguishing chromophobe renal cell carcinoma from clear cell renal cell carcinoma and renal oncocytoma.

The distinction between chromophobe renal cell carcinoma (ChRCC), clear cell renal cell carcinoma (CRCC) and renal oncocytoma may cause a diagnostic dilemma. The usefulness of DOG1, cyclin D1, CK7, CD117 and vimentin in the differential diagnosis of these renal epithelial tumors was investigated. DOG1 was positive in ChRCC (32 of 32, 100%) and in renal oncocytoma (21 of 21, 100%). In contrast, DOG1 was absent in all CRCC (0 of 30). Cyclin D1 was positive in renal oncocytomas (17 of 21, 81%) but negative in the ChRCC (0/23) and CRCC (0 of 30). CK7 was positive in ChRCC (30 of 32, 94%), but was negative in oncocytoma (only scattered single positive cells), and was only focal positive in two cases of CRCC. CD117 was expressed in 88% of ChRCC (28 of 32), 86% of renal oncocytoma (18 of 21), and was negative in all CRCC (0 of 30). Twenty-six of the 30 cases of CRCC were positive (87%) for vimentin with prominent membrane staining patterns. All 23 chromophobe carcinomas were negative for vimentin and 15 of 21 oncocytomas demonstrated focal vimentin positivity, but less than 10%. The above results demonstrate that: (1) DOG1 was very sensitive and specific marker for distinguish ChRCC from CRCC; (2) Cyclin D1 was a useful marker to discriminate between ChRCC and renal oncocytoma; (3) CK7 and CD117 were useful markers to distinguish ChRCC from renal oncocytoma and CRCC. (4) Vimentin was helpful for distinguishing clear cell RCC from chromophobe and oncocytoma (87% of clear cell RCC positive, negative in chromophobe, only focally positive in oncocytoma). (5) CK8/18, CK19, CD10, β-catenin and E-cadherin could not be used to distinguish ChRCC from renal oncocytoma and CRCC.