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Introduction: Langerhans' cell histiocytosis (LCH) is a group of rare diseases with a wide variety of presentations across age groups. We describe a case of pulmonary LCH diagnosed at a late stage despite having additional skin findings for several years. Case description: A 32-year-old male presented with acute exacerbation of chronic dyspnea resulting in markedly decreased functional capacity as well as cutaneous lesions. He had smoked cigarettes for 10 years with no occupational exposures. The patient also complained of a pruritic rash in his axillary and groin areas. His vitals were within normal limits. His exam was notable for diminished right lung sounds and expiratory wheezes bilaterally. A chest x-ray showed marked emphysema and bilateral upper lobe reticular opacities suggestive of scarring. Computerized tomography of the chest showed loculated right pneumothorax and hyperinflated lungs with destructive changes secondary to numerous irregular, thick walled cysts and scattered irregular pulmonary nodules. Diagnosis was ultimately confirmed with biopsy of concomitant cutaneous lesions and characteristic radiographic findings on Chest CT. The patient started inhaled corticosteroids, inhaled anticholinergic, and inhaled short-acting beta agonists. He was sent home with oxygen and strongly encouraged to abstain from smoking. Discussion: LCH is characterized by end-organ infiltration of proliferating monoclonal Langerhans' cells, a histiocyte involved in antigen presentation. The highest incidence of LCH is between ages 5-10 years; the adult incidence is estimated to be less than half as frequent than the pediatric, about one patient in 500,000. LCH most commonly involves the skin, bones, and lungs. Pulmonary LCH (PLCH) is interesting in that it has a peak incidence in ages 20-40 years and occurs almost exclusively in smokers (> 90% of cases). Conclusion: Smoking cessation is the cornerstone of management of PLCH. It has been hypothesized that tobacco smoke can incite the production of cytokines by alveolar macrophages, leading to increased recruitment of histiocytes to the lung parenchyma. In isolated pulmonary pathology, lung transplant with smoking cessation is often curative.