HBME‐1, MOC‐31, WT1 and calretinin: an assessment of recently described markers for mesothelioma and adenocarcinoma

<jats:sec><jats:title>Aims</jats:title><jats:p>To evaluate HBME‐1, WT1, calretinin and MOC‐31 in the differential diagnosis of pleural mesothelioma and adenocarcinoma of the lung.</jats:p></jats:sec><jats:sec><jats:title>Methods and results</jats:title><jats:p>Paraffin‐embedded formalin‐fixed blocks from six reactive pleuras, 42 mesotheliomas and 40 adenocarcinomas were used. Sections were stained for Leu‐M1, HBME‐1, calretinin, WT1 and MOC‐31. Leu‐M1 was positive or equivocal in 34% of mesotheliomas and in 78% of adenocarcinomas; reactive pleuras were all negative. HBME‐1 was positive or equivocal in 76% of mesotheliomas and in 73% of adenocarcinomas; five reactive pleuras were positive. Calretinin was positive or equivocal in 92% of mesotheliomas and in 73% of adenocarcinomas; two reactive pleura were equivocal and four were positive. WT1 was positive or equivocal in 72% of mesotheliomas (excluding autopsy cases) and in 20% of adenocarcinomas; all reactive pleuras were positive. MOC‐31 was positive or equivocal in 5% of mesotheliomas and in 90% of adenocarcinomas; all reactive pleuras were negative. The reaction with Leu‐M1 was graded as equivocal in 25% of the adenocarcinomas. All 24 of the autopsy cases of mesothelioma were negative for WT1 and in many operative specimens only the periphery was stained.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>Neither calretinin nor HBME‐1 are sufficiently discriminatory to be of use, even as members of a panel of antibodies. WT1 shows some promise, but it cannot be used on autopsy material. The utility of MOC‐31 is confirmed, and outperforms Leu‐M1.</jats:p></jats:sec>