[Sarcoidosis].

Sarcoidosis is the most frequent interstitial lung disease of unknown origin affecting patients of younger age in many cases. In Germany its incidence is higher than that of tuberculosis. Diagnosis is made by demonstration of epitheloid, non-necrotizing granuloma in pulmonary parenchyma and by exclusion of other granulomatous disorders such as mycobacteriosis, berylliosis, or hypersensitivity pneumonitis. Its etiology is still elusive and since it is a systemic disease any organ can be involved. The lung is most frequently involved and, therefore, diagnosis can easily be made by bronchoscopy with transbronchial biopsy and bronchoalveolar lavage. Frequently a favorable spontaneous course takes place but in about one third of the cases a chronic course of disease is seen which requires systemic treatment with prednisolone. In progressive disease despite prednisolone treatment the combination with azathioprine or methotrexate might be helpful.