Pulmonary Langerhans cell histiocytosis (PLCH) is a well known entity in adults but is exceedingly rare in children. It is better described in adults than in children. Smoking is a major etiological factor in adulthood. We report a case of a previously healthy 16-year-old male with a history of cigarette smoking, who presented with cough with sputum, breathlessness, easy fatigability and loss of appetite for two weeks. He was first diagnosed with bronchiectasis according to the cystic pulmonary changes demonstrated by computed tomography. After appropriate treatment, there was no sign of clinical improvement. A lung biopsy confirmed Langerhans cell histiocytosis (LCH). The definitive diagnosis was isolated pulmonary LCH. PLCH should be considered in the etiology of cystic lung diseases. Isolated pulmonary LCH is rare so such cases are needed to be reported and followed-up to understand the treatment response and course of this illness.

Keywords: Langerhans cell histiocytosis, children, pulmonary involvement, smoking