BACKGROUND Pulmonary Langerhans cell histiocytosis (PLCH) is a rare cystic lung disease usually affecting young adults. It is predicted that PLCH is a lung tumor precursor associated with dysfunction of the myeloid dendritic cells in the lung. CASE SUMMARY A 70-year-old male patient presented with chronic cough and sputum. He had symptoms for 5 years and described shortness of breath on exertion for the previous 3 years. He had a 60 packs/year smoking history. Computerized tomography of the thorax revealed an 11-mm nodule in the right lung lower lobe superior segment and a 7-mm nodule in the right lung lower lobe poster basal segment. Those two nodules were resected by means of right thoracoscopic surgery. Pathological evaluation revealed a squamous cell carcinoma and PLCH. CONCLUSION Coexistent squamous cell carcinoma and PLCH suggest possible association between PLCH and lung cancer.