Immunohistochemical panels for differentiating epithelial malignant mesothelioma from lung adenocarcinoma - A study with logistic regression analysis

Immunohistochemistry provides an important indicator for differential diagn osis between pleural malignant mesothelioma and lung adenocarcinoma, which have complex therapeutic and medicolegal implications. To pinpoint a reliab le, restricted panel of markers, the authors evaluated the efficacy of sele ct commercial antibodies in a series of patients with confirmed clinicopath ologic diagnosis of mesothelioma or lung adenocarcinoma with the aid of mul tiple logistic classification tables. Specimens of 46 mesotheliomas and 20 lung adenocarcinomas were examined with calretinin, thrombomodulin, cytoker atins (CKs) 5/6, and high-molecular weight CKs (indicators of mesothelioma) , alongside MOC 31, Ber-EP4, and carcinoembryonic antigen (CEA; indicators of lung adenocarcinoma). Of the mesotheliomas, 40 of 46 (87%) were positive with calretinin, 29 of 46 (63%) with thrombomodulin, 40 of 46 (87%) with C Ks 5/6, and 41 of 46 (89%) with high-weight CKs; five of 46 mesotheliomas ( 11%) were focally reactive with MOC 31, four of 46 (9%) with Ber-EP4, and t wo of 46 (4%) with CEA. Of the lung adenocarcinomas, 18 of 20 (90%) were po sitive with MOC 31, 20 of 20 (100%) with Ber-EP4, and 17 of 20 (85%) with C EA; and two of 20 (10%) were focally reactive with calretinin, one of 20 (5 %) with thrombomodulin, none of 20 (0%) with CKs 5/6, and five of 20 (25%) with high-weight CKs. Multiple logistic modeling indicated two batteries of three antibodies permitting more than 98% overall accuracy: Ber-EP4 plus C Ks 5/6 plus calretinin, and Ber-EP4 plus CKs 5/6 plus CEA.