Calretinin, thrombomodulin, CEA, and CD15: A useful combination of immunohistochemical markers for differentiating pleural epithelial mesothelioma from peripheral pulmonary adenocarcinoma

The distinction between pleural epithelial mesothelioma and peripheral lung adenocarcinoma involving the pleura is still an important diagnostic probl em for surgical pathologists. The aim of our study was to identify the most specific and sensitive markers for the positive identification of mesothel ioma to select a limited, appropriate panel of antibodies to differentiate between mesothelioma and adenocarcinoma. Forty-two cases of epithelial meso theliomas and 23 cases of pulmonary adenocarcinomas were stained with the f ollowing antibodies: anticalretinin, antithrombomodulin, anti-CD44H, and mo noclonal antibody HBME-1. We also studied the value of other markers in cur rent use: cytokeratins AE1/AE3 and CAM5.2, epithelial membrane antigen (EMA ), carcinoembryonic antigen (CEA, BerEP4, B72.3, and CD15. Of the mesotheli omas, 42 stained for calretinin, 39 (92.8%) for thrombomodulin, 45 stained for CD44H, and 41 (97.6%) stained for HBME1. Among negative markers, 4 (9.5 %) mesothelioma cases stained for CEA, 5 :11.9%) stained for Ber-EP4, 6 (14 .2%) stained for B72.3, and 2 (4.7%) stained for CD15. Of the lung adenocar cinomas, 2 (8.7%) cases showed reactivity for calretinin, 5 (21.7%) for thr ombomodulin, 13 (56.5%) for CD44H, all for HBME-1, 22 (95.6%) for CEA, 22 ( 95.6%) for Ber-EP4, 8 (34.7%) for B72.3, and all for CD15. In conclusion, c alretinin and thrombomodulin were the most specific positive mesothelial ma rkers, whereas CD44H and HBME-1 showed high sensitivity but very low specif icity. Among negative markers, we advocate the use of CEA and CD15 which we re the mast specific in differentiating mesotheliomas from adenocarcinomas. Copyright (C) 2001 by W.B. Saunders Company.