Abstract: ［Abstract］ Objective To investigate the clinical and muscle biopsy features of primary dermatomyositis （DM） and the influence of lymphocyte subsets with treatment. Methods Twenty?seven cases of primary dermatomyositis were retrospectively analyzed in terms of clinical features， electromyogram and MRI results. All the patients underwent quadriceps femoris muscle biopsy on the right thigh. Histochemical （HE， COX， SDH） staining was used to observe the morphology of muscle fibers， electron microscopy and the characteristics of myofibrillar membrane after immunohistochemical staining； PLT， CRP， WBC， IgG， IgA， IgM and IgE were observed before and after 12 weeks of treatment. Changes of CD3+， CD4+， CD8+， CD19+B， CD16+56?NK cells were detected. Results After 12 weeks of treatment， the proportion of CD19+B cells was lower than that of baseline （P<0.05）. The proportion of CD8 and CD3+T cells was higher than that of baseline. The change of CD16+56?NK cells was not significant before and after treatment（P>0.05）. Levels of IgG， IgM and IgA of immunoglobulin were lower than that of baseline（P<0.05）. Diffuse abnormal signal shadows in muscle space and subcutaneous adipose layer and electromyogram showed progressive muscle damage. In 25 cases， myofibrillar necrosis， perifascicular atrophy， no intracytoplasmic lipid droplets or glycogen vacuoles， no broken red fibers or edge vacuoles， no obvious proliferation of fibrous adipose tissue in perimyofibrillar membrane and endomyofibril， no obvious inflammatory cells， normal COX activity were observed. Dystrophin indicated that the myofibrillar membrane was expressed uniformly and continuously. Under electron microscopy， muscle cells showed atrophy， degeneration and necrosis. Among them， 2 （7.4%） had normal muscle enzymes， the expression of Dystrophin in muscle fibers was suspected to be decreased， COX staining of one （3.7%） case showing a decrease with a few muscle fibers， and SDH/COX showed a few blue fibers， one （3.7%） case had no typical perifascicular atrophy under light microscopy， while the electron microscopy showed an increase in lipid droplets. Conclusion Light microscopy of dermatomyositis showed necrosis of individual muscle fibers and perifascicular atrophy locally. MRI can show muscle lesions of JDM patients sensitively and noninvasively. Immune disorders of B and T cells are involved in the pathogenesis of dermatomyositis， and can also be used as indicators of therapeutic efficacy of dermatomyositis.

Key words: muscle biopsy, pathological character, dermatomyositis, lymphocyte subsets

摘要： ［摘要］ 目的 探讨初发皮肌炎（dermatomyositis，DM）的临床及肌肉活检特征及治疗前后淋巴细胞亚群的影响。方法 回顾性分析27例初发皮肌炎患者临床特征、肌电图及MRI结果；全部患儿均进行右侧大腿股四头肌肌肉活检，记录组织化学（HE、COX、SDH）染色后光镜下观察肌纤维形态、电镜及免疫组化后肌纤维膜特点；观察治疗12周前后PLT、CRP、WBC、免疫球蛋白IgG、IgA、IgM、IgE和CD3+T细胞、CD4+T细胞、CD8+T细胞、CD19+B细胞、CD16+56?NK细胞的变化。结果 治疗12周后CD19+B细胞的比例较基线降低（P<0.05），CD8、CD3+T细胞比例较基线升高、治疗前后CD16+56?NK细胞较基线变化不明显（P>0.05），免疫球蛋白IgG、IgM、IgA较基线下降（P<0.05），27例患儿进行了MRI（右侧大腿）检测，所见双侧臀部、大腿、膝部及双侧小腿上端肌肉、肌肉间隙及皮下脂肪层弥漫性异常信号影，肌电图均显示所测肌肉进行性肌源性损害。25例肌酶明显升高，光镜下均见到个别肌纤维坏死，局部见束周萎缩，未见胞浆内脂滴或糖原空泡，未见破碎红纤维或镶边空泡，肌束膜和肌内膜纤维脂肪组织增生不明显，炎症细胞不明显，COX酶活性正常，Dystrophin提示肌纤维膜呈阳性表达，表达均匀、连续。电镜下肌细胞大小不等，呈现萎缩、变性、坏死改变，其中2例（7.4%）肌酶正常，肌纤维Dystrophin表达可疑减弱（图2），1例（3.7%）COX染色示少数肌纤维酶活性减低，且SDH/COX见少数蓝纤维（图3），1例（3.7%）光镜下未见典型束周萎缩（图4），电镜显示脂滴增多。结论 皮肌炎光镜下均见到个别肌纤维坏死，局部见束周萎缩，MRI 检查能灵敏且无创地显示JDM 患者的肌肉病变。B、T细胞的免疫紊乱参与了皮肌炎发病，同时也可作为皮肌炎治疗疗效判别的指标。

关键词: 肌肉活检, 皮肌炎, 淋巴细胞亚群, 病理特点