We report a case of a previously healthy 17-year-old male with a history of cigarette smoking, who presented with acute development of respiratory distress. Computed tomography demonstrated cystic pulmonary changes. A lung biopsy confirmed Langerhans cell histiocytosis (LCH). The definitive diagnosis was isolated pulmonary LCH, a disorder that is infrequently found in adults, and rarely in children. We know of only one other case of a previously healthy adolescent cigarette smoker who developed isolated pulmonary LCH. The etiology of pulmonary LCH is unknown, but smoking has been considered as a risk factor.