台灣華人多發性肌炎及皮肌炎患者之Anti-Mi-2抗體與其臨床表現－－單一醫學中心之病例分析與文獻回顧

Clinical correlation between anti-Mi-2 antibodies and polymyositis/dermatomyositis in Chinese patients

目的：文獻報告肌炎專一性抗體存在於原發性肌炎並且可能和預後有關，但anti-Mi-2抗體在華人族群則尚未詳細研究過，本研究希望找出華人族群含anti-Mi-2抗體的患者及其臨床表現。方法：採集於台中榮總過敏免疫風濕科於2001-2012年間追蹤的89位多發性肌炎及皮肌炎病患血清，檢測其anti-Mi-2抗體並回溯性收集患者其基本資料、臨床表徵、檢查結果並和過去研究比較。結果：共6位病人（6.7%）發現有anti-Mi-2抗體，且皆為皮肌炎患者，男女各半。6位皆表現有臉部紅斑、5位有高春氏皮疹、上胸部V型皮疹、甲溝旁紅疹；2位有向陽性紅疹及披肩疹，anti-Mi2抗體陽性病人較易有臉部紅斑、上胸部V型皮疹。Anti-Mi-2抗體的存在和惡性腫瘤及間質性肺病之發生無關。結論：本研究顯示本院的多發性肌炎及皮肌炎患者中anti-Mi-2抗體陽性比率，其結果和過去研究發現接近，anti-Mi-2抗體和間質性肺病及惡性腫瘤無關，長期的追蹤以及更多病患的參與有助於決定anti-Mi-2抗體的盛行率以及是否影響這些病人的預後。

Objective: Myositis-specific antibodies are present in idiopathic inflammatory myopathies (IIM), and may have an association with prognosis of polymyositis (PM) and dermatomyositis (DM). To our knowledge, few studies have been conducted on anti-Mi-2 positivity in the Chinese population. The aim of this study was to investigate the prevalence of anti-Mi-2 antibody in PM/DM in the Taiwan Chinese population and explore the clinical characteristics among these patients. Methods: Eighty-nine patients with PM/DM followed up at the rheumatology outpatient clinics of Taichung Veterans General Hospital (TCVGH) were enrolled between Jan. 1st 2001 and Jan. 1st 2013. Anti-Mi-2 IgG antibodies were detected by enzyme fluoroimmunoassay. Demographic data, clinical features, and laboratory findings were analyzed. Results: Anti-Mi-2 antibodies were detected in six (6.7%) of 89 participants with IIM. The female-male ratio was 1:1. All six patients had an initial presentation of malar rash. Five had Gottron’s sign, V sign, or periungual erythema. Two patients had heliotrope rash or Shawl sign. Anti-Mi-2 antibody positivity was associated with a higher chance of developing malar rash and V sign, but not with malignancy or interstitial lung disease (ILD). Conclusion: The frequency of anti-Mi-2 antibodies in our PM/DM cohort was comparable with that in previous studies. Anti-Mi-2 positivity was not associated with ILD or malignancy. Long-term follow-up of a large cohort is needed to determine the true prevalence and prognostic value of anti-Mi2 antibodies in patients with PM/DM.