Serial computed tomography and lung function testing in pulmonary Langerhans' cell histiocytosis.

Little is known about longitudinal lung function variation in patients with pulmonary Langerhans' cell histiocytosis (LCH). The contribution of serial lung computed tomography (CT) to managing these patients has not been evaluated. This long-term retrospective study included 49 patients who were serially evaluated by lung CT and pulmonary function tests. The lung function variation was categorised as improvement or deterioration. The extent of the CT lesions was correlated with lung function. Lung function deteriorated in ∼60% of the patients. Forced expiratory volume in 1 s (FEV(1)) and diffusing capacity of the lung for carbon monoxide (D(L,CO)) were the parameters that most frequently deteriorated. A subgroup of patients experienced a dramatic decline in FEV(1) within 2 yrs of diagnosis. Airway obstruction was the major functional pattern observed. In a multivariate analysis, % predicted FEV(1)at diagnosis was the only factor associated with the incidence of airway obstruction. The increase in cystic lesions on the lung CTs was associated with impaired lung function but did not anticipate the decline in FEV(1) or D(L,CO). Serial lung function tests are essential for following patients with pulmonary LCH, who frequently develop airway obstruction. A lung CT at diagnosis is informative, but routine sequential CTs seem less useful. A prospective study is needed to characterise those patients with early progressive disease.