Pulmonary Langerhans cell histiocytosis associated with lingual carcinoma

A 57-year-old man who was a heavy smoker was admitted to our hospital for further evaluation of abnormal shadows on a chest X-ray film. Chest radiography and a computed tomography (CT) scan revealed nodular lesions and multiple thin-walled cysts in both lungs. Histopathological examination of one of these cystic lesions showed that the predominant cellular population was Langerhans cells, with the cytoplasm testing positive for S-100 protein and the cell membrane showing a positive reaction for CD1a. The pathological diagnosis was pulmonary Langerhans cell histiocytosis (LCH). A lingual carcinoma that had been detected simultaneously was treated with neoadjuvant therapy and the patient was advised to stop smoking. However, only limited improvement was seen on follow-up chest CT. In view of this, a radical resection of the lingual carcinoma was performed. There was a subsequent dramatic improvement in the pulmonary LCH. Langerhans cells may play a role in the immune response to tumors. In this patient, we suggest the possibility that both the habitual smoking and the lingual carcinoma may have contributed to the development of pulmonary LCH.