[Pulmonary histiocytosis X].

Pulmonary histiocytosis X is a histiocytic granulomatosis of yet unknown etiology and of partial immunopathogenesis. The incidence ist about 5% compared to sarcoidosis. Almost all patients are smokers, the age peak lies between 20 and 40 years. Leading symptoms are non-productive cough and dyspnea, often it is only detected radiologically by chance. The x-ray shows bilateral nodular, later reticular changes. The characteristic ring figures may be detected only by tomography. Until recently diagnosis was made exclusively by lung biopsy, but now bronchoalveolar lavage may be already diagnostic. Early corticosteroid therapy seems to prevent the progression to the fibrotic-bullous end-stage in almost all cases.