RESUMO
Adult pulmonary Langerhans cell histiocytosis (PLCH) is a rare disorder of unknown etiology that occurs predominantly in young smokers, with an incidence peak at 20-40 years of age. In adults, pulmonary involvement with Langerhans cell histiocytosis usually occurs as a single-organ disease and is characterized by focal Langerhans cell granulomas infiltrating and destroying distal bronchioles. We report a 23-year-old asymptomatic male smoker with a non specific interstitial infiltrate found in preventive chest X ray examination. A high resolution chest CT scan showed multiple cystic structures predominating in the upper lobes, with small centrilobular nodules. A transbronchial biopsy showed a lymphocytic lung infiltrate with Langerhans cells. A surgical biopsy confirmed the diagnosis of pulmonary Langerhans cell histiocytosis. After six months of follow up, the patient is in good conditions.