Background Spontaneous pneumomediastinum is a rare complication and a poor prognostic factor of dermatomyositis (DM). But the mechanisms, outcome, and prognostic factors of DM associated pneumomediastinum have not yet been evaluated.
Objectives To study the clinical features and prognostic factors of spontaneous pneumomediastinum in DM.
Methods A retrospective study of 301 patients with an initial diagnosis of DM was carried out, focusing mainly on patients complicated by pneumomediastinum. The clinical records including demographic variables, clinical features, laboratory data, treatment and outcomes were collected. We analyzed English published cases and combined those that were exploitable with ours for an investigation of the factors associated with poor survival.
Results Among the 301 patients with DM, pneumomediastinum was observed as a complication in 8 patients, with the prevalence rate of 3.0%. Three of the patients were female, five were male, and the mean age was 48 years (range 33-67). Seven of the eight patients (87.5%) had interstitial lung disease (ILD); three patients (37.5%) had severe pulmonary infection; four patients (50%) had associated cutaneous vasculopathy. All the patients had negative anti-Jo-1 antibody, only two patients had positive ANA. Six patients (75%) had normal serum creatine kinase levels before the onset of pneumomediastinum, but eight patients (100%) had elevated lactate dehydrogenase (LDH) level. The outcome was favorable in three of these patients; five patients died within 1 month. Poor survival was associated with severe pulmonary infection (P=0.042) and elevated LDH level (more than two times of upper limit; P=0.028).
Conclusions Most DM associated pneumomediastinum is accompanied by ILD. Pneumomediastinum may develop in the early course of DM; it occurs even after the improvement of muscle weakness. Death was associated with severe pulmonary infection and elevated LDH. Corticosteroids, intravenous immunogloblin and immunosuppressive therapy can result in complete resolution.
Disclosure of Interest None declared