Bronchogenic carcinoma developing during a long-term course of pulmonary Langerhans' cell histiocytosis

A 30-year-old man patient was admitted to our clinic with complaints including cough, dyspnea, and chest pain. He had been diagnosed with pulmonary Langerhans' cell histiocytosis (LCH) 9 years previously. HRCT of the thorax demonstrated the presence of diffuse emphysematous areas in both lungs with a honeycomb appearance, an increase in reticular density at the lower lobes, a mass lesion in the left hilus, and a mass lesion at the lower lobe of the left lung. Histological diagnosis of TBNA from the right lower paratracheal and subcarinal lymph nodes was adenocarcinoma. Chemotherapy was begun, but the patient died due to respiratory failure after two courses of chemotherapy. We present this case as an example of the rare development of bronchogenic carcinoma during the long-term course of LCH.