Langerhans cell histiocytosis (LCH) usually affects different organs or bones. Isolated pulmonary disease is rare in childhood. We report about a 6-year-old girl with progressive pulmonary insufficiency, onset of clubbing at 4 years of age and honeycombing lung infiltrations on X-ray films. The radiological suspicion of primary pulmonary LCH was confirmed by the presence of CD1a positive cells in the bronchoalveolar lavage fluid. Other organs were not involved. The girl was treated according to the LCH-III International Study Protocol with a good response. Follow-up showed no reactivation of LCH but a reduced vital capacity and signs of interstitial pulmonary involvement on a CT scan.
Conclusion: Langerhans cell histiocytosis should be considered in the aetiology of cystic lung diseases. Early responders to treatment have a high likelihood of becoming free of disease. However, pulmonary fibrosis is an important mechanism of lung remodelling in pulmonary Langerhans cell histiocytosis and the long-term prognosis is unclear.