Tabriz University of Medical Sciences Journal of Research in Clinical Medicine 2717-0616 7 1 2019 03 10 Pulmonary Langerhans cell histiocytosis with Skin involvement; an amazing case report 32 36 10.15171/jarcm.2019.006 EN Sara Saniee Niloofar Afshari Saeed Kashefi Journal Article 10.15171/jarcm.2019.006 2018 10 21 2018 12 13 Introduction: Langerhans cell histiocytosis (LCH) is a rare disease characterized by infiltration of large mononuclear or dendritic cells in one or more organs. Lung can be involved alone or with other organs in this complication. Case Report: We report a 33-year-old smoker man with LCH in whom both the lung and the skin were involved. He was referred to our department due to malodourous, crusted and scaly erythematous patches, plaques, and pustules involved scalp and flexural area. His medical problem started with pulmonary involvement. He experienced spontaneous pneumothorax, and was suffering progressive dyspnea for years. Cryo-transbronchial lung biopsy previously had been done. Pathology report was pulmonary LCH (PLCH). Weid skin biopsy. Histologic analysis of skin with haemotoxylin and eosin (H&E) staining and immunohistochemistry (IHC) exam with S100 and CDa1 confirmed the diagnosis of LCH. Conclusion: It is important to consider PLCH in the setting of recurrent pneumothorax and progressive dyspnea in middle-aged smoker patient. PLCH may be associated with skin involvement.