ALK and collecting duct carcinoma: The differential diagnosis of ALK-RCC is quite broad, primarily due to the presence of variable and diverse morphologies that can be observed in ALK-RCC, which may mimic other renal entities, such as renal medullary carcinoma (in children and adolescents), collective duct carcinoma, papillary RCC, MiTF RCC (TFE3 and TFEB), mucinous tubular and spindle cell carcinoma, and thyroid-like follicular RCC.