We hypothesized that TFE3 may be a useful diagnostic marker of SFT and, thus, sought to assess TFE3 expression in 50 SFTs via immunohistochemical analysis; compared these expression patterns to those of other tumour types to assess the specificity of TFE3 marker for SFTs; and evaluated the association of TFE3 with gender, tumour size, mitotic rate score, and SFT patient prognosis. This evidence concerns the gene TFE3 and neoplasm.