Renal cell carcinoma with t(6,11): A case report and review of literature.

Renal cell carcinomas (RCCs) with t(6,11) are very rare tumours. Only a few cases have been reported so far. t(6,11) results in fusion of alpha gene and transcription factor EB (TFEB) gene resulting in the overexpression of TFEB. The specific light and immunohistochemical features help in the diagnosis of this rare type of tumor. We report a case of t(6,11) RCC in a 38-year-old female who was incidentally found to have a right renal mass. We present this case to emphasize the typical light microscopic picture of this extremely rare tumor. Two population of cells are seen: larger cells with abundant cytoplasm and smaller cells with scant cytoplasm. Smaller cells are arranged around hyaline nodules resulting in the formation of characteristic pseudorosettes. Immunohistochemically, these tumors are diffusely positive for vimentin and focally positive for HMB 45 and CD 117. Knowledge about the typical biphasic light microscopic appearance and the characteristic immunohistochemical features help in the diagnosis of this rare type of translocation associated RCC.