TFE3 and neoplasm: As the morphology of both Xp11.2 RCCs and ASPS are non-specific and there are a lot of technical difficulties with the available ancillary tools – IHC limited by equivocal results, karyotyping limited by availability of viable tumor cells and RT-PCR limited by RNA quality, we tried to validate and utilize TFE3 break-apart fluorescence in-situ hybridization (FISH) assay in FFPE tissue to confirm the diagnosis of an Xp11.2 RCC and ASPS.