Presented is a typical case of Erdheim-Chester disease (ECD) wherein the severe pulmonary manifestation led to an open lung biopsy and eventual morphologic recognition of the nonspecific clinical symptoms. The pulmonary involvement is described in almost 20% of cases and is prognostically unfavourable. About 20 cases of Erdheim-Chester disease were published and more than half of them had lethal outcome. The ECD affecting seriously lungs appears as non-specific interstitial lung disease and usually does not enter the broad clinical differential diagnosis. A detailed bibliography with special attention to the pulmonary involvement by this enigmatic disease is presented.

        Key words: Erdheim-Chester disease - lungs - skeleton - interstitial pneumonia - histiocytosis - Langerhans cells - histiocytosis X