As immunoreactivity for TFE3 is a feature associated with Renal cell Carcinoma (RCC) characterized by the presence of TFE3 gene fusions13, an interphase FISH by using a break apart probe — designed to detect translocations involving the TFE3 gene at Xp11.2— was performed on formalin-fixed, paraffin-embedded tissues (FFPE) on the area of the cysts immunoreactive for TFE3 of left atrophic kidney. This evidence concerns the gene TFE3 and renal cell carcinoma.