Letters to the Editor

INCREASED FREQUENCY OF HLA-B8 IN JUVENILE DERMATOMYOSITIS

Dermatomyositis (DM) is a rare idiopathic inflammatory myopathy characterized by muscle weakness and cutaneous manifestations in adults and children. Calcinosis, a complication of DM, is the abnormal deposition of insoluble calcium salts in tissues, including skin, subcutaneous tissue, tendons, fascia, and muscle. Calcinosis is more commonly seen in juvenile DM (JDM), but also develops in adult DM. Although the mechanism of calcinosis remains unclear, several pathogenic hypotheses have been proposed, including intracellular accumulation of calcium secondary to an alteration of the cellular membrane by trauma and inflammation, local vascular ischemia, dysregulation of mechanisms controlling the deposition and solubility of calcium and phosphate, and mitochondrial damage of muscle cells. Identifying calcinosis biomarkers is important for early disease detection and risk assessment, and may lead to novel therapeutic targets for the prevention and treatment of DM-associated calcinosis. In this review, we summarize myositis autoantibodies associated with calcinosis in DM, histopathology and chemical composition of calcinosis, genetic and inflammatory markers that have been studied in adult DM and JDM-associated calcinosis, as well as potential novel biomarkers.

Juvenile dermatomyositis (JDM) is a rare, potentially life-threatening systemic autoimmune disease primarily affecting muscle and skin. Recent advances in the recognition, standardised assessment and treatment of JDM have been greatly facilitated by large collaborative research networks. Through these networks, a number of immunogenetic risk factors have now been defined, as well as a number of potential pathways identified in the aetio-pathogenesis of JDM. Myositis-associated and myositis-specific autoantibodies are helping to sub-phenotype JDM, defined by clinical features, outcomes and immunogenetic risk factors. Partially validated tools to assess disease activity and damage have assisted in standardising outcomes. Aggressive treatment approaches, including multiple initial therapies, as well as new drugs and biological therapies for refractory disease, offer promise of improved outcomes and less corticosteroid-related toxicity.