A case report.

Langerhans cell histiocytosis (LCH) is a rare and unexplained disease that can involve in any organ or system in the body and displays a variety of clinical manifestations. A 31-year-old man, who had a more than 10-year smoke history, initially presented dry cough, polydipsia and diuresis, with recurrent spontaneous pneumothorax. Pulmonary high-resolution computed tomography showed diffuse cystic and nodular lesions. Langerhans cell histiocytosis was confirmed by a transbronchial cryobiopsy. The disease is involved in the lung, pituitary, thyroid, liver, lymph node, and skin. Glucocorticoid or systemic chemotherapy is commonly used in the treatment for this disease. BRAF gene mutation inhibitor is a new direction for the treatment.