Clinical outcomes of pulmonary Langerhans'-cell histiocytosis in adults

Background: Pulmonary Langerhans'-cell histiocytosis is an uncommon interstitial lung disease in adults. It has an unpredictable course and may be associated with an increased susceptibility to the development of malignant neoplasms. Methods: We reviewed the records of 102 adults with histopathologically confirmed pulmonary Langerhans'-cell histiocytosis to ascertain their vital status and whether cancer had been diagnosed. The health status of surviving patients was quantified with the use of the 36-Item Short-Form General Health Survey. Factors potentially associated with survival after the diagnosis of pulmonary Langerhans'-cell histiocytosis were analyzed with the Cox proportional-hazards model. Results: The median follow-up period was 4 years (range, 0 to 23). There were 33 deaths, 15 of which were attributable to respiratory failure. Six hematologic cancers were diagnosed. The overall median survival was 12.5 years, which was significantly shorter than that expected for persons of the same sex and calendar year of birth (P<0.001). In a univariate analysis, variables predictive of shorter survival included an older age (P=0.003), a lower forced expiratory volume in one second (FEV₁) (P=0.004), a higher residual volume (P=0.007), a lower ratio of FEV₁ to forced vital capacity (P=0.03), and a reduced carbon monoxide diffusing capacity (P=0.001). Conclusions: The survival of adults with pulmonary Langerhans'-cell histiocytosis is shorter than that in the general population, and respiratory failure accounts for a substantial proportion of deaths among such patients.