The neoplastic cells of metastatic prostatic adenocarcinoma were positive for NKX3.1 and PSA, negative for CDX‐2, CK7, and TTF1; whereas the neoplastic cells of lung mucinous adenocarcinoma were positive for CDX2, CK7, and napsin‐A (focal), negative for TTF1, NKX3.1, and PSA. Here, KRT7 is linked to mucinous adenocarcinoma.