Science and Education Publishing American Journal of Medical Case Reports 2374-216X 4 5 2016 5 30 Tension Pneumothorax as the Presentation of Pulmonary Langerhans Histiocytosis 173 174 EN Conor McCartney Department Internal Medicine, St. Louis University, United States Andrew Freeman Ravi Nayak Internal Medicine, Program Director Division of Pulmonary, Critical Care and Sleep Medicine, St. Louis University, United States AJMCR2016458 10.12691/ajmcr-4-5-8 2015 12 29 2016 4 5 2016 5 28 A 36 year old male smoker presented to the emergency department with shortness of breath. A chest x-ray showed a tension pneumothorax. Chest tube was placed urgently. CT scan showed upper lobe predominant cystic lung lesions. Biopsy confirmed the diagnosis of pulmonary Langerhans Histiocytosis.