MUSCULAR DISEASE: Edited by Ichizo NishinoUpdate on dermatomyositisTanboon, Jantimaa,b; Nishino, Ichizob,c,d Author Information aDepartment of Pathology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand bDepartment of Neuromuscular Research, National Institute of Neuroscience (NIN), National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan cDepartment of Genome Medicine Development dDepartment of Clinical Genome Analysis, Medical Genome Center (MGC), National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan Correspondence to Jantima Tanboon, MD, Department of Pathology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand. Tel: +66 2 419 6529; e-mail: [email protected] Current Opinion in Neurology 35(5):p 611-621, October 2022. | DOI: 10.1097/WCO.0000000000001091 Buy Metrics Abstract Purpose of review This review summarizes and comments on current knowledge in dermatomyositis. Recent findings The 2018 European Neuromuscular Centre classification of dermatomyositis has been challenging by the discovery of clinicopathological features associated with dermatomyositis-specific antibody (DMSA) that were not incorporated in the original criteria. These features include but may not be limited to the presence of perifascicular necrosis in anti-Mi-2 dermatomyositis; presence of diffuse nonperifascicular sarcoplasmic myxovirus resistance protein A expression in anti-MDA5 dermatomyositis; and dermatomyositis sine dermatitis in anti-NXP-2 dermatomyositis. Variations and subclassifications within the same DMSA subtypes are observed: anti-MDA5 dermatomyositis is clinically subcategorized into good, intermediate, and poor prognostic subgroups; concurrent anti-CCAR1 and anti-TIF1-γ positivity identify anti-TIF1-γ-positive patient with a lower risk for cancer-associated myositis. Owing to distinct IFN1-signaling pathway activation in dermatomyositis, JAK-STAT inhibitor – the pathway-targeted therapy, have been studied with promising results in refractory dermatomyositis and some new-onset dermatomyositis. In addition, the potential serum biomarkers for IFN1 pathway activation are being investigated for their performance in monitoring the disease activity and the efficacy of the treatment. Summary DMSA, evidence of prominent IFN1 pathway activation, and risk/severity-associated biomarkers would likely play major roles in future dermatomyositis classification, disease monitoring, and treatment decision. Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.