[Morphological diagnostics of malignant pleural mesothelioma]

The World Health Organization (WHO) classification differentiates between pleural tumors of mesothelial and mesenchymal origin as well as lymphoproliferative disorders, with malignant mesotheliomas forming the most common pleural primary tumor. Histologically, epithelioid (40-60 %), sarcomatoid (20-40 %), and biphasic mesotheliomas (20-40 %) are distinguished. The certain morphological diagnosis of a malignant pleural mesothelioma requires the establishment of mesothelial differentiation by means of an appropriate panel of antibodies to exclude pleural dissemination of a pulmonary or extrapulmonary epithelial malignancy and also requires the establishment of at least focal invasive growth to distinguish from reactive mesothelial proliferation. The exclusion of a malignant pleural mesothelioma may induce further differential diagnostic considerations, e. g. concerning the assignment to a certain primary tumor after the establishment of carcinomatous pleuritis.