Gene expression discriminates chromophobe renal cell carcinoma and oncocytoma

The overlapping characteristics are best explained by a common cellular origin, and the biologic differences between chRCC and oncocytoma are therefore of considerable interest in terms of carcinogenesis, diagnosis and clinical management. Previous studies have been relatively limited in terms of examining the differences between oncocytoma and chromophobe RCC. Methods : Gene expression profiling using the Affymetrix HGU133Plus2 platform was applied on chRCC (n=15) and oncocytoma specimens (n=15). Supervised analysis was applied to identify a discriminatory gene signature, as well as differentially expressed genes. Immunohistochemical validation was performed in an independent set of tumors. Results : A novel 14 probe-set signature was developed to classify the tumors internally with 93% accuracy, and this was successfully validated on an external data-set with 94% accuracy. Parafibromin, aquaporin 6, and synaptogyrin 3 were novel immunohistochemical markers effectively discriminating the two pathologic entities. Conclusion : Gene expression profiles and pathway analysis effectively distinguish chRCC from oncocytoma. We have generated a novel transcript predictor that is able to discriminate between the two entities accurately, and which has been validated both in an internal and an independent data-set, implying generalizability. We have identified a series of immunohistochemical markers that are clinically useful in discriminating chRCC and oncocytoma.