Smoking preceded pulmonary involvement in adults with Langerhans cell histiocytosis diagnosed in childhood.

Two patients with childhood Langerhans cell histiocytosis (LCH) (aged 2 and 6 y at diagnosis) in whom pulmonary involvement was diagnosed in adulthood, 23 and 12 y later, respectively, are presented. In each patient, smoking preceded the diagnosis of pulmonary involvement by 3 y, providing further evidence that smoking is a risk factor in the development of pulmonary LCH.