Background: Anti-melanoma differentiation-associated gene 5 (anti-MDA5) antibody-positive dermatomyositis (DM) has low survival rate, whereas macrophage activation syndrome (MAS) is a severe and life-threatening syndrome associated with autoimmune diseases. Their coexistence is very rare. This study aimed to describe the prevalence, clinical characteristics, and outcomes of anti-MDA5 antibodies-positive DM patients complicated with MAS. Methods: In this retrospective study, we enrolled DM patients with anti-MDA5 antibodies, who were hospitalized between 2016 and 2020 and included patients diagnosed with MAS. Results: We identified four (2%) DM patients with anti-MDA5 antibodies. They were females with interstitial lung disease (ILD). The level of aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and ferritin were significantly higher in the MAS group than those without MAS ( p < 0.05). Patients with MAS were significantly more likely to develop a dysphagia ( p = 0.012). Literature review revealed eight similar cases. Together with the present study, we identified 12 patients complicated with ILD. The median age of disease onset was 52 years with a male to female ratio of 1:6. The median duration between DM onset and MAS diagnosis was 3 months. The mortality of MAS in anti-MDA5 antibody-positive DM was 50%. Patients who died were older than those who survived (56.7 years versus 35.5 years; p = 0.015). Conclusions: MAS was rare in anti-MDA5 antibody-positive DM. The higher the level of AST, LDH, and ferritin, the greater the risk of MAS. They were associated with high mortality rates, particularly in older patients.

IntroductionReports of unexpected side effects have accompanied the vaccination of larger proportions of the population against coronavirus disease 2019 (COVID-19), including a few cases of inflammatory myopathy (IM). In a bid to improve understanding of the clinical course of vaccine complications, a systematic review of reported cases of IM following COVID-19 vaccination has been conducted.MethodsThe PRISMA guideline 2020 was followed. Two independent investigators systematically searched PubMed and Embase to identify relevant studies published up to July 2022, using the following keywords: COVID-19 Vaccine, inflammatory myositis. The Joanna Briggs Institute critical appraisal tools were used for the risk of bias.ResultsA total of 24 articles presenting clinical features of 37 patients with IM following COVID-19 vaccine were identified. Female patients composed 59.5% of cases and 82.4% had been vaccinated with BNT162b2 or ChAdOx1. Onset of symptoms occurred within 2 weeks of the first or second vaccine dose in 29 (85.3%) patients and included muscular weakness in 54.1% and skin rash in 71.4% of patients. Myositis specific autoantibodies (MSAs) and myositis associated autoantibodies (MAAs) were reported in 28 patients. Specific clinical subtypes of myositis, reported in 27 patients, included 22 (81.5%) cases of dermatomyositis (DM) and 3 (11.1%) cases of immune-mediated necrotizing myopathy (IMNM). Following treatment, 32 (86.5%) patients showed improvement on follow-up.ConclusionCOVID-19 vaccine may induce various clinical myositis subtypes and related antibodies. Muscular weakness was the most common presenting symptom. Clinicians should be aware of this unexpected adverse event following COVID-19 vaccination and arrange for appropriate management.Systematic review registrationINPLASY https://inplasy.com/inplasy-2022-9-0084/ [INPLASY202290084].