A large number of immunohistochemical markers that can facilitate the distinction between epithelioid pleural
mesotheliomas and pulmonary peripheral
adenocarcinomas have recently become available. The aim of this study is to compare the value of these new markers with others that are already commonly used for this purpose and to determine which are, at present, the best for discriminating between these
malignancies. Sixty epithelioid
mesotheliomas and 50
lung adenocarcinomas were investigated for expression of the following markers:
calretinin,
cytokeratin 5/6, WT1,
thrombomodulin,
mesothelin, CD44S, HBME-1,
N-cadherin,
E-cadherin, MOC-31, thyroid transcription factor-1 (TTF-1), BG-8 (Lewisy),
carcinoembryonic antigen (CEA), Ber-EP4,
B72.3 (TAG-72), leu-M1 (CD15), CA19-9,
epithelial membrane antigen (EMA), and
vimentin. All (100%) of the
mesotheliomas reacted for
calretinin,
cytokeratin 5/6, and
mesothelin, 93% for WT1, 93% for EMA, 85% for HBME-1, 77% for
thrombomodulin; 73% for CD44S, 73% for
N-cadherin, 55% for
vimentin, 40% for
E-cadherin, 18% for Ber-EP4, 8% for MOC-31, 7% for BG-8, and none for CEA,
B72.3, leu-M1, TTF-1, or CA19-9. Of the
adenocarcinomas, 100% were positive for MOC-31, Ber-EP4, and EMA, 96% for BG-8, 88% for CEA, 88% for
E-cadherin, 84% for
B72.3, 74% for TTF-1, 72% for leu-M1, 68% for HBME-1, 48% for CD44S, 48% for CA19-9, 38% for
mesothelin, 38% for
vimentin, 30% for
N-cadherin, 14% for
thrombomodulin, 8% for
calretinin, 2% for
cytokeratin 5/6, and none for WT1. After analyzing the results, it is concluded that
calretinin,
cytokeratin 5/6, and WT1 are the best positive markers for differentiating epithelioid
malignant mesothelioma from pulmonary
adenocarcinoma. The best discriminators among the
antibodies considered to be negative markers for
mesothelioma are CEA, MOC-31, Ber-EP4, BG-8, and
B72.3. A panel of four markers (two positive and two negative) selected based upon availability and which ones yield good staining results in a given laboratory is recommended. Because of their specificity and sensitivity for
mesotheliomas, the best combination appears to be
calretinin and
cytokeratin 5/6 (or WT1) for the positive markers and CEA and MOC-31 (or
B72.3, Ber-EP4, or BG-8) for the negative markers. An extensive and detailed review of the literature is also provided.