RESUMEN
Pulmonary Langerhans cell histiocytosis belongs to the spectrum of the Langerhans' cell histiocytosis. The common point is tissue infiltration by Langerhans' cell granuloma. But the pulmonary type occurs predominantly in young adults and is associated with tobacco. The most frequently encountered symptoms are cough and dyspnea. Twenty-five to 35% of the cases are incidental findings. 20% of cases present with extra-thoracic lesions including skin, bone and hypothalamo-pituitary axis. On scanning images the lung parenchyma is infiltrated at the beginning by stellar nodules of less than 10 mm, which evolve either gradually to form cysts or towards remission, spontaneous or induced by the treatment. With pulmonary function testing, the two types of anomalies [obstruction and restriction] are observed. The reduction in diffusing capacity observed in 60 to 90% of the cases reflects the pulmonary vascular involvement. Detec-tion of more than 5% of CD-la cells in bronchiolo-alveolar lavage fluid and transbronchial biopsies are not sensitive. Treatment is controversial and includes primarily smoking cessation and corticosteroid therapy at the early nodular stage