ALK and sarcomatoid carcinoma: Because of its heterogeneous and diverse morphologies, the differential diagnosis of ALK-RCC varies widely, involving renal medullary carcinoma, collecting duct carcinoma, papillary RCC, MiT family translocation RCC, clear cell RCC with rhabdoid features, metanephric adenoma, thyroid-like follicular RCC, and mucinous tubular and spindle-cell carcinoma (MTSCC) [4].