Since clear cell RCC (ccRCC) is the most common renal carcinoma in adults, it should be differentiated from Xp11.2/TFE3 RCC first; moreover, papillary RCC (pRCC), which is the second most common subtype of RCC, often cannot be distinguished from Xp11.2/TFE3 RCC in routine histopathological examination. The gene discussed is TFE3; the disease is nonpapillary renal cell carcinoma.