[Primary nonspecific chronic pleurisy (author's transl)].

Cytologic examinations of pleural exudate and cyto-histological examination of biopsies taken from the pleura give useful contributions in the differential diagnosis of primary chronic nonspecific pleurisy. In the early stage of disease the cellular findings are characteristic and enable easy differentiation of mesothelioma. Later on in primary chronic nonspecific pleurisy alterations of mesothelial cells can be seen which mimic tumorous cells and may be erroneously taken for mesothelioma cells. Quantity and quality of these alterations of nucleus and cytoplasma of mesothelial cells in primary chronic nonspecific pleurisy can be distinguished from tumor cells of mesothelioma by critical evaluation in the majority of cases.