Jantima Tanboon, Michio Inoue, Shinya Hirakawa, Hisateru Tachimori, Shinichiro Hayashi, Satoru Noguchi, Shigeaki Suzuki, Naoko Okiyama, Manabu Fujimoto, Ichizo Nishino
Neurology 2021 Jan 19To identify the characteristic pathologic features of dermatomyositis (DM) associated with anti-Mi-2 autoantibodies (anti-Mi-2 DM). We reviewed 188 muscle biopsies from patients (1) pathologically diagnosed with DM through the sarcoplasmic expression for the myxovirus-resistant protein A and (2) serologically positive for 1 of 5 DM-specific autoantibodies (DMSAs) (anti-Mi-2, n = 30; other DMSAs, n = 152) or negative for all 5 DMSAs (n = 6). We then compared the histopathologic and immunohistochemical features of patients with anti-Mi-2 DM to those with non-Mi-2 DM and patients with anti-synthetase syndrome (ASS) (n = 212) using the t test, Fisher exact test, and a logistic regression model. Patients with anti-Mi-2 DM showed significantly higher severity scores in muscle fiber and inflammatory domains than non-Mi-2 DM patients. The presence of perifascicular necrosis, increased perimysial alkaline phosphatase activity, and sarcolemmal membrane attack complex deposition was more frequent in patients with anti-Mi-2 DM (p < 0.01). After Bonferroni correction, there were no significant differences in the percentages of the features mentioned above between the patients with anti-Mi-2 DM and those with ASS (p > 0.01). Perifascicular necrosis and perimysial pathology, features previously reported in ASS, are common in patients with anti-Mi-2 DM. Our findings not only assist in differentiating anti-Mi-2 DM from other DM subtypes but also suggest the possibility of an overlapping mechanism between anti-Mi-2 DM and ASS. This study provides Class II evidence that the muscle biopsies of DM patients with anti-Mi-2 autoantibodies are more likely to demonstrate higher severity scores in muscle fiber and inflammatory domains. © 2020 American Academy of Neurology.
Jantima Tanboon, Michio Inoue, Shinya Hirakawa, Hisateru Tachimori, Shinichiro Hayashi, Satoru Noguchi, Shigeaki Suzuki, Naoko Okiyama, Manabu Fujimoto, Ichizo Nishino. Pathologic Features of Anti-Mi-2 Dermatomyositis. Neurology. 2021 Jan 19;96(3):e448-e459
PMID: 33277422
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