Translocation renal cell carcinomas: an evolving entity and a member of the microphthalmia transcription factor-associated family of tumors

Translocation renal cell carcinomas (tRCC) are a novel, rare, and distinct clinicopathologic entity first described in 2001. They are caused by genetic translocations which fuse transcription factor genes, TFE3 or TFEB, with a promoter region leading to overexpression of the transcription factor. TFE3 and TFEB are members of the MiT family of transcription factors. Other tumors also driven by overexpression of members of the MiT family include alveolar soft part sarcoma, clear cell sarcoma and 30%-40% of melanomas. Recently some authors have suggested classifying these tumors along with tRCC as the 'MiT family of cancers.' We report 3 cases of this rare subtype of renal cell carcinoma and provide an up to date literature review of the topic. This report highlights the clinical and pathologic heterogeneity of these tumors. Efforts are under way to find a therapy to target the gene fusion products or their downstream effectors which drive growth of these tumors.