[Pulmonary Langerhans cell histiocytosis in adults]

Pulmonary Langerhans-cell histiocytosis in adults is a rare condition of unknown etiology characterized by the accumulation of Langerhans cells organized in granulomas involving the distal bronchioles and destroying their walls. It occurs in young subjects who smoke, with frequency peaking between 20 and 40 years. High-resolution thoracic CT is essential for diagnosis; in typical forms it shows a combination of nodules, cavitary nodules, thick-walled cysts, and thin-walled cysts. Diagnostic certainty requires a surgical lung biopsy, by videothoracoscopy, but only if a specialist considers it indicated. It is difficult to predict the disease course for any given patient. A prospective multicenter cohort study currently underway should provide more information about the natural history of this disease. Management is empirical, for efficacy has not been proved for any treatment. Stopping smoking is especially important to prevent the added development of chronic obstructive pulmonary disease (COPD), cardiovascular complications, or the onset of bronchopulmonary cancer, the frequency of which appears elevated in these patients. Oral corticosteroids are used to treat disease progression, especially in the symptomatic mainly nodular forms, but their efficacy for respiratory function has not been shown. Vinblastine, the reference treatment for multisystem forms of Langerhans-cell histiocytosis, is not indicated for pulmonary involvement in adults. Better knowledge of the pathogenic mechanisms involved in this condition should eventually make it possible to develop innovative treatment strategies. The creation of the national reference center for Langerhans-cell histiocytosis has given new momentum to clinical and pathophysiologic research on this orphan disease.