DETECTION OF FOUR NOVEL RENAL TUMORS CASES HARBORING RBM10-TFE3 FUSIONS. DETECTION OF FOUR NOVEL RENAL TUMORS CASES HARBORING RBM10-TFE3 FUSIONS

Microphtalmia-associated-transcriptional-factor-family translocation renal cell carcinoma (MiTF-tRCC) currently includes two main subtypes: “TFEB-tRCC” most often characterized by a t(6;11)(p21;q13) that generates a fusion of TFEB with MALAT1 and “TFE3-tRCC” characterized by rearrangements of TFE3 at Xp11.23 (2-3) that produce a variety of fusion genes. FISH is a handy method in routine practice that allows the detection of a rearrangement of TFE3. However, it reaches its limits in cases of micro-inversions or insertions: in fact paracentric microinversions that involve GRIPAP1 (Xp11.23) (23, Classe) or RBM10 (Xp11.3), very close to TFE3 , are most often undetectable.We report the clinical, immunohistological, genomic and molecular description of four novel TFE3-tRCC with RBM10-TFE3 fusion detected by targeted RNASeq analysis that illustrate the difficulties of diagnosis, especially in reason of disconcerting negative TFE3 FISH results. Overall design: screening of 3 cases of TFE3 translocated renal cell carcinomas by SNP array with affymetrix platform