[Erdheim-chester disease: a rare cause of interstitial lung disease]

Erdheim-Chester disease is a rare non-Langerhans' cell histiocytosis of unknown etiology with typical osteosclerotic long-bone findings. However, clinical symptoms are mostly due to disease involvement of other tissues, particularly of the lung, heart and retroperitoneum.

A 58-year-old man presented with fatigue, diffuse pain of the lower extremities, dyspnea, and a dry cough. Physical examination was unremarkable. Chest X-ray revealed an extensive bilateral pulmonary inter interstitial process. Computed tomography demonstrated pulmonary fibrosis, periaortic fibrosis of the thoracic aorta, and retroperitoneal fibrosis. The diagnosis of Erdheim-Chester disease was confirmed by minimally invasive lung biopsy. Steroid therapy was not tolerated. Following a stable interval of 18 months there was a disease progression, which could be stabilized after the initiation of cyclophosphamide therapy.

In patients with extensive pulmonary fibrosis and coincidence of other organ manifestations such as periaortic or retroperitoneal fibrosis and particularly in case of symmetrical osteosclerotic bone lesions, Erdheim-Chester disease should be considered. Immunosuppressive therapy can lead to a stabilization or even improvement of the disease.