Erdheim-Chester disease is a disseminated non-Langerhans' cell histiocytosis involving multiple organs with characteristic sclerotic musculoskeletal lesions. This is the report of the case of a 53-year-old woman with extensive and progressive pulmonary disease. Computed tomography scans revealed diffuse infiltrative lung disease. Thoracoscopic lung biopsy and a biopsy of the right femur lesion were performed. The histopathology revealed that she had non-Langerhans' cell histiocytosis; Erdheim-Chester disease. The characteristic lesions of Erdheim-Chester disease, including involvement of the orbit, pericardium, periaorta, and bone were detected. This helped to further confirm that the patient had Erdheim-Chester disease with associated pulmonary involvement. As Erdheim-Chester disease is a rare non-Langerhans' cell histiocytosis that may be misdiagnosed as interstitial lung disease or other pulmonary disorders, this diagnosis should be considered in the differential diagnosis of such lung lesions.