2026 年 43 巻 3 号 p. 298-302
In 2025, an updated “Clinical Practice Guideline for Polymyositis and Dermatomyositis 2025” was published, reflecting major advances in the understanding and management of inflammatory myopathies. Since the original definition of polymyositis (PM) and dermatomyositis (DM) in 1975, substantial progress in muscle pathology and the identification of myositis–specific autoantibodies have led to a refined disease classification. Currently, inflammatory myopathies are subdivided into PM, DM, immune–mediated necrotizing myopathy, and antisynthetase syndrome. Accurate diagnosis requires an integrated assessment of muscle weakness, cutaneous manifestations, and associated systemic complications, together with detailed laboratory and instrumental evaluations, including serum creatine kinase levels, skeletal muscle imaging, electromyography, and muscle histopathology.
Glucocorticoids remain the first–line therapy for PM/DM, while immunosuppressive agents, intravenous immunoglobulin, and plasma exchange are employed as adjunctive treatments according to disease severity and treatment response. Although optimal therapeutic strategies for refractory cases have not yet been fully established, multiple biologic agents targeting key immunopathogenic pathways are currently under active development.
Given the multidisciplinary nature of PM/DM management, clinical perspectives may vary among specialties. Widespread implementation of this guideline is expected to facilitate the establishment of a shared disease concept and to promote phenotype–driven therapeutic strategies. Standardization of clinical subtypes will enable the design of high–quality clinical trials and accelerate the development of novel targeted therapies for inflammatory myopathies.
