Overlap Syndrome Consisting of Polymyositis/Dermatomyositis and ANCA-Associated Vasculitis According to the 2022 ACR/EULAR Criteria for Vasculitis: A Korean Single-Centre Study.

The present study applied the 2022 American College of Rheumatology and European Alliance of Associations for Rheumatology classification criteria (the 2022 ACR/EULAR criteria) for antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) to ANCA-positive patients with polymyositis (PM)/dermatomyositis (DM). Also, this study investigated how many patients could be diagnosed with overlap syndrome consisting of PM/DM and AAV. Twelve ANCA-positive patients with PM/DM were included and analysed in this study. The 2022 ACR/EULAR classification criteria for microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA), and eosinophilic GPA (EGPA) are scoring systems, and when a total score is over five in cases of MPA and GPA and over six in cases of EGPA, AAV can be classified. The median age of 12 ANCA-positive patients (six with PM and six with DM) was 54.0 years and one patient (8.3%) was male. Of the 12 ANCA-positive patients with PM/DM, 11 had myeloperoxidase (MPO)-ANCA (or perinuclear [P]-ANCA) and the remaining one had proteinase 3 (PR3)-ANCA (or cytoplasmic [C]-ANCA). Nine (75.5%) and one (8.3%) ANCA-positive patients with PM/DM were diagnosed with overlap syndrome consisting of PM/DM and MPA and overlap syndrome consisting of PM/DM and GPA, respectively. The main contributors to the classification of MPA and GPA were interstitial lung disease and renal vasculitis, along with ANCA positivity, respectively. In conclusion, this study was the first to demonstrate that 83.3% of them could be diagnosed with overlap syndrome consisting of PM/DM and AAV according to the 2022 ACR/EULAR criteria for AAV.