关键词: 肌肉活检, 皮肌炎, 淋巴细胞亚群, 病理特点

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