Objective To retrospectively analyze the clinical and pathological features of 8 patients with hy-pomyopathic dermatomyositis (HDM), and to evaluate the clinical and pathological value of HDM. Methods The clinical data of 40 patients with dermatomyositis who underwent muscle biopsy in our hospital between January 2010—2015 were collected. According to the diagnostic criteria of HDM, 8 patients were included in the study, in-cluding 6 females and 2 males. The age of onset was between 45 and 65 years old, and the disease duration was more than 6 months. The clinical manifestations were skin changes of typical dermatomyositis. No clinical manifestation of limb weakness was found. The creatine kinase (CK) level was normal in 7 cases, and mild elevated in 1 case. Elec-tromyography (EMG) showed myogenic damage in 5 cases. Eight patients underwent biopsy for bicipital muscle of arm, and the specimens were processed with standard histological, enzyme histochemistrical and immunohistochemical stainings [CD8, CD20, major histocompatibility complex type Ⅰ antigen (MHC-Ⅰ)]. Results Mild-moderate fat droplets in muscle fibers were increased in 8 HDM patients, with mild macrophage infiltration and B-lymphocyte infil-tration at the perimysium. A small number of perifascicular distributed small circular amyotrophic muscle fibers was found in 3 patients, accompanied with necrosis and regeneration of muscle fibers. All HDM patients showed deep staining of MHC-Ⅰat the perifascicular distributed muscle fibers and non-specific esterase deep staining at the peri-fascicular distributed intermuscular capillaries. Conclusion MHC-1 positive expression may be a useful screening tool due to the lack of routine diagnosis of HDM.%目的：回顾性分析8例低肌病性皮肌炎（HDM）的临床和肌肉病理改变特点，探讨HDM的临床、病理诊断价值。方法收集我院2010—2015年行肌肉活检的40例皮肌炎患者，按照HDM的诊断标准筛选出8例，女性6例，男性2例，发病年龄46～65岁，病程均超过6个月，临床表现为典型皮肌炎皮肤改变，无肢体无力的临床表现。7例患者肌酸激酶正常，1例轻度升高。5例患者肌电图呈肌源性损害。同时对8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CD8、CD20免疫组织化学染色。结果8例HDM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细胞浸润。3例HDM患者出现少数小圆状萎缩肌纤维呈束周分布的特点，伴随肌纤维的坏死再生。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。结论由于诊断HDM常规技术检测的缺失，MHC-Ⅰ阳性表达可能是一个有用的筛选工具。
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