CTSK and renal cell carcinoma: TFE3‐RCC is generally diagnosed based on immunohistochemical (IHC) analysis of markers such as TFE3, MLANA, HMB45, and CTSK.[7, 10, 11] However, these markers do not always reliably distinguish TFE3‐RCC from KIRC and KIRP.[8, 9] GPNMB and TRIM63 have been recently identified as potential biomarkers for TFE3‐RCC, although some KIRC and KIRP cases also stain positive for these markers.[12, 13] We previously identified nicotinamide riboside kinase 2 (NMRK2) as a potential indicator of TFE3‐RCC;[14] however, further validation in clinical trials is needed.