Pulmonary involvement in juvenile dermatomyositis: a two-year longitudinal study

Objective. To investigate the prevalence and features of asymptomatic pulmonary involvement in juvenile dermatomyositis (JDM). Methods. Twelve JDM patients underwent pulmonary function tests at baseline, 12 and 24 months. Disease activity, duration, serum lactate dehydrogenase (LDH) values and antinuclear antibody (ANA) titres were also evaluated. Results. Five patients showed lung impairment at baseline and four at 12 and 24 months. Forced expiratory volume in 1 s, forced vital capacity (FVC), carbon monoxide diffusing capacity (DLCO) and alveolar volume were the most frequently altered variables, indicating a restrictive pattern and impairment of diffusion. The prevalence and features of pulmonary alterations did not change during follow-up. FVC values were significantly lower in active JDM patients and were inversely related to LDH. DLCO values were significantly lower in ANA-positive patients. About half of the patients of this small case series of JDM had asymptomatic lung disease. Conclusions. We suggest that lung function should be evaluated at disease onset and regularly during follow-up, as pulmonary function tests can detect otherwise unpredictable pulmonary involvement.