Diagnosis of Xp11 translocation renal cell carcinomas in adult patients under 50 years: interest and pitfalls of automated immunohistochemical detection of TFE3 protein.

Renal cell carcinomas associated with Xp11.2 translocations form a new and little known entity of the WHO 2004 classification. An immunohistochemical (IHC) test aiming at demonstrating the nuclear expression of the protein TFE3, product of a gene frequently involved in translocation, has been proposed as a diagnostic tool. The aims of this work were to define our evaluation criteria of the immunohistochemical test with the antibody anti-TFE3 and to describe new cases of renal cell carcinomas with TFE3 translocations. Using immunohistochemistry with antibody anti-TFE3, we retrospectively studied 83 renal cell carcinomas diagnosed at Edouard Herriot Hospital and Biomnis Laboratory, Lyon, between 2003 and 2009. The patients were 50 years old or younger. We detail our experience of the IHC test using the anti-body anti-TFE3 and the interpretation criteria. This work has enabled two new cases of renal cell carcinomas associated with TFE3 translocations to be detailed, confirmed by molecular biology. The TFE3 immunohistochemical test is a useful tool that demands strict interpretation criteria. In our experience, more than 80% of nuclei stained with an intensity of ++ to +++ is necessary to suspect the diagnosis of Xp11 translocation renal cell carcinoma.