DIAGNOSTIC-TOOLS FOR DIFFERENTIATING BETWEEN PLEURAL MESOTHELIOMA ANDLUNG ADENOCARCINOMA IN PARAFFIN-EMBEDDED TISSUE .1. IMMUNOHISTOCHEMICAL FINDINGS

Specimens of 27 histologically definite mesotheliomas and 34 proven ad enocarcinomas were examined with a panel of 14 antibodies: pan-epithel ial antibody Lu-5, anti-keratin-18, anti-keratin-7, Ber-EP4, anti-Leu- M1, HEA-125, anti-carcino-embryonic antigen (CEA), anti-blood group-re lated antigens (anti-BGR A, B, H), B 72.3, anti-placental alkaline pho sphatase (PLAP), anti-vimentin and BMA-120 used to determine their val ue in the differentiation between pleural mesothelioma and lung adenoc arcinoma. Lu-5, anti-cytokeratin-7 and -18, B 72.3 and PLAP reacted in a high percentage of cases with both mesothelioma and adenocarcinoma. Anti-CEA and anti-Leu-M1 did not react with any of the 27 mesotheliom as tested but showed a reaction in 75% (anti-CEA) and 66% (anti-Leu-M1 ) of the lung adenocarcinomas. Seventeen percent of the adenocarcinoma s and 96% of the mesotheliomas showed a positive reaction with anti-vi mentin. Ber-EP4 was demonstrated in all lung adenocarcinomas, but only in 2 mesotheliomas in a focal manner (7%). HEA-125 and anti-BGR A, B, H reacted with 83% (HEA-125) and 75% (anti-BGR A, B, H) of the lung a denocarcinomas. The statistical parameters, sensitivity and efficiency were estimated and a normogram for judging the diagnostic power of a single antibody for the differential diagnosis of mesothelioma versus adenocarcinoma was developed. According to this, Ber-EP4, HEA-125, ant i-BGR A, B, H and anti-CEA were, in descending order, the most powerfu l discriminatory antibodies.