CALB2 and adenocarcinoma: In doubtful cases, IHC stains can confirm the mesothelial origin; calretinin, WT-1, HBME-1, and D2-40 are positive in mesothelial cells and usually negative in adenocarcinoma, while MOC-31, Ber-EP4, B72.3 (BRST-3), and CEA are positive in adenocarcinoma and usually negative in mesothelial cells.