THE HISTOPATHOLOGICAL DIAGNOSIS OF MALIGNANT MESOTHELIOMA V PULMONARYADENOCARCINOMA - REPRODUCIBILITY OF THE HISTOPATHOLOGICAL DIAGNOSIS

In a randomized design we examined the interobserver variation in the histopathological diagnosis of adenocarcinoma of the lung and malignan t mesothelioma. In three rounds, three pathologists assessed slides fr om 42 tumours originally diagnosed as adenocarcinomas, malignant mesot heliomas or benign lesions in the pleura. In the first round the asses sments were made on haematoxylin and eosin (H and E) stained sections; in the second, on H and E sections plus sections stained with histoch emical mucin stains; and in the final round, the diagnoses were made o n H and E sections and sections stained with a panel of antibodies aga inst various antigens (cytokeratin, EMA, CEA, Ber-EP4, B72.3, Leu-M1, vimentin and S-100 protein) said to be of value in the differential di agnosis. The overall interobserver agreements for the three rounds wer e 0.659, 0.802 and 0.817; the kappa values were 0.461, 0.681 and 0.690 . It is concluded that differentiation between adenocarcinoma of the l ung and malignant mesothelioma should be made on sections stained with H and E and mucin and/or immunohistochemical staining reactions, incl uding antibodies against B72.3, Ber-EP4 and CEA.