低肌病性皮肌炎的临床和肌肉病理特点六例分析

The clinical and pathological features of hypomyopathic dermatomyositis： a report of 6 cases

目的了解低肌病性皮肌炎的临床表现和肌肉病理改变特点。方法收集我院2008年1月至2010年6月行肌肉活检的62例皮肌炎患者，按照低肌病性皮肌炎的诊断标准筛选6例，其中4例患者肌电图呈肌源性损害。同时对6例患者进行肱二头肌活检，标本进行组织学、酶组织化学染色和免疫组织化学染色，后者的第一抗体分别为CD8、CD20和CD68鼠抗人单克隆抗体以及标记主要组织相容性复合物I型抗原（MHC—I）的鼠抗人单克隆抗体。结果6例患者的肌纤维内脂肪滴均有轻至中度增多，肌束衣出现个别巨噬细胞浸润和B淋巴细胞浸润。3例患者出现个别小圆状萎缩肌纤维呈束周分布的特点，伴随个别肌纤维的坏死再生。所有患者束周分布的肌纤维膜存在MHC-I深染，束周分布的肌间毛细血管非特异性酯酶深染。结论部分低肌病性皮肌炎患者的骨骼肌病理改变类似经典皮肌炎，提示此病可能是单纯无肌病皮肌炎和经典皮肌炎的中间型。

Objective To explore the clinical and pathological features of hypomyopathic dermatomyositis （HDM）. Methods Six cases of HDM among 62 cases of dermatomyositis diagnosed between January 2008 and June 2010 were collected and analyzed. Four were women and 2 were men. The age of onset was between 45 and 65 years old, with disease duration of more than 6 months. All HDM patients presented with DM-specific skin lesions, but without muscle weakness. Serum creatine kinase （CK） level was within normal limits in 5 and mild elevated in 1. Electromyogram showed myogenic changes in 4 cases and normal in the other 2 patients. Muscle biopsies were carried out in the left biceps branchii in all of them. The muscle sections were processed with standard histological procedures, enzyme histochemistrieal and immunohistochemieal stains were carried out. The antibodies used for immunohistoehemieal stains were anti- CD8, anti-CD20, anti-CD68, and anti-MHC-I monoclonal antibodies. Results Muscle biopsies showed a variable amount of macrophages and B-lymphocytes infiltrating in the peri-mysium and fascicle area. Three of them presented with mild peri-fascicular fiber atrophy with fiber necrosis and regeneration. Lipid droplets increased mildly in muscle fibers. Capillaries distributing around perifascicular regions were darkly stained in nonspecific esterase stain. Perifascicular fibers showed immune-reactivity to MHC-I antibody. Conclusion The myopathological changes of HDM mimic classical dermatomyositis in some cases. HDM might be an intermediate presentation between pure amyopathic dermatomyositis and classical dermatomyositis.