Characteristics and Outcomes of Juvenile Dermatomyositis (JDM) in Thai Children: Experience from a Tertiary Referral Center

Abstract

Background: Juvenile dermatomyositis (JDM) is the most common autoimmune myositis in children. However, there is a paucity of data on the clinical characteristics of JDM patients in Thailand. Objective: To describe the clinical manifestations, investigations, treatments, complications, and outcomes of JDM in Thailand. Materials and Methods: A bidirectional descriptive study based on past medical records review. All children younger than15 years diagnosed with JDM by Bohan and Peter criteria at King Chulalongkorn Memorial Hospital between January 2010 and December 2022 were enrolled. Results: Thirteen cases were identified with 69% female. The median age at diagnosis and median time to diagnosis were 3.4 (IQR 2 to 6.5) years and 3.5 (IQR 1.2 to 8) months, respectively. The common clinical presentations at disease onset were weakness at 100%, Gottron papules at 69%, and heliotrope rash at 46%. Lactate dehydrogenase was elevated in all cases at diagnosis. Evidence of muscle inflammation was found in 78% of biopsies, 80% of EMGs, and 100% of MRIs. The most common myositis specific Ab was anti-NXP2 at 64%. Most patients had polyphasic disease courses. More than half of the patients, or 62%, developed calcinosis. Six of thirteen cases received recommended treatment with prednisolone and methotrexate at diagnosis. One patient with calcinosis had a good response with infliximab. Conclusion: The present review underscores that JDM patients with younger age at diagnosis will need to be monitored closely and need aggressive long-term treatment. Prompt treatment should be managed according to the severity of symptoms to improve clinical outcomes and prevent serious complications. Keywords: JDM; Calcinosis cutis; Myositis autoantibody; Children; Developing countries