[Osteoplastic pneumopathy (disseminated bone formation in the lung)]

8 cases of pneumophathia osteoplastica (ppo) of branching type observed at patients having no vascular deformities and one case of a focal ppo at a patient with mitral stenosis are reported. Pathogenesis of the ppo of branching type in the majority of cases could not be clarified since the process appeared to be in the phase of definitive bone formation. Nevertheless in one of the cases in a septum of Y shape in addition to collagen fibres ending in bone tissue numerous elastic fibres have also been revealed. This fact, considering the presence of a normal bronchus in the area seems to evidence vascular origin of the lesion. The latter hypothesis could be verified by the bone-formation in the media of a vessel wall in another case. Further, in a case of primary chronic polyarthritis with ppo, bone-formation could be seen in the perivascular lung tissue with necrotizing pulmonal arteritis. Considering this finding the possibility of the primary role of necrotizing pulmonal arthritis in the pathogenesis of ppo have to be taken into account. Ppo should be classified as one of the alveolocapillary block syndromes. In some cases it may have clinico-pathological significance. It may lead to bronchietasis, emphyseme or cor pulmonale chronicum.