Langerhans cell Histiocytosis can present as a single or multiple lesion and can affect one or several organ systems. A 41-year-old woman with a history of multisystemic Langerhans cell Histiocytosis invading lung and thyroid was admitted with left-sided spontaneous pneumothorax. Here we report a case of uncommon pulmonary Langerhans-cell Histiocytosis presenting with spontaneous pneumothorax as a multisystemic Langerhans cell Histiocytosis.