In accordance with the definition of mucinous colorectal adenocarcinoma, we propose proceeding in a similar manner for clear cell carcinoma, i.e., tumors with histologically proven clear cell differentiation in > 50% of the tumor area should be defined as “clear cell adenocarcinoma” and those with ≤ 50% clear cell changes as “adenocarcinoma with clear cell features.” The clear cells may express AFP, glypican-3, and SALL4. The gene discussed is GPC3; the disease is clear cell adenocarcinoma.