Clinical features of patients with anti-melanoma differentiation-associated gene-5 antibody-positive dermatomyositis complicated by spontaneous pneumomediastinum.

Background: Dermatomyositis (DM) with autoantibody against melanoma differentiation-associated gene-5 (MDA5) is characterized by elevated risk of rapidly progressive interstitial lung disease (RP-ILD) with a potentially fatal course. Pneumomediastinum (PNM) is a common pulmonary manifestation which accompanies ILD. However, the clinical features of the patients with anti-MDA5 antibody-positive DM who develop PNM remain unclear.
Methods: We retrospectively examined 31 patients with DM having anti-MDA5 antibody and compared the clinical features between patients with PNM (PMN(+)) (n = 11) and those without (PNM(-) (n = 20). In addition, we evaluated the treatment-related prognoses in PNM(+) group.
Results: CT score (total ground-glass opacity (GGO) score, P = 0.02; total fibrosis score, P = 0.02) before treatment, and mortality (P = 0.04) were significantly higher in PNM(+) group. The cumulative survival rate as assessed by Kaplan-Meier method was significantly lower for the PNM(+) group (P = 0.02). Among 11 PMN(+) patients, 9 patients (9/11, 81.8%) underwent intensive immunosuppression therapy for RP-ILD, and 5 patients (5/11, 45.5%) did not respond to it and died from the respiratory failure. At the time of diagnosis of PNM, nonsurvivors had worse liver function (ALT, P = 0.03; LDH, P = 0.01), worse respiratory status (A-aDO2, P = 0.01), and worse CT score (total GGO score, P < 0.01).
Conclusions: A subgroup of patients with DM having anti-MDA5 antibody complicated by PNM as well as RP-ILD did respond to intensive immunosuppression therapy. Initial aggressive immunosuppressive therapy should be considered for these patients.Key Points• This study clearly demonstrate the presence of PNM was associated with elevated risk of death due to respiratory failure from RP-ILD among patients with DM having circulating anti-MDA5-antibody.•This study demonstrate evaluation of CT image may be helpful to find patients with better response to the intense immunosuppression therapy for the patients with DM having circulating anti-MDA5-antibody and PNM.