目的:粘液病毒耐药蛋白A(MxA)是I型干扰素(IFN1)途径激活标记,MxA肌浆表达是目前公认的皮肌炎(DM)的高度特异性标记。然而,我们经常观察到内皮小管网状包涵体(TRI),另一个替代IFN1激活标记,在各种重叠的肌体中。这项研究的目的是检查这些肌肽中的MxA表达。
方法:我们对多种肌肽进行了MxA免疫染色。
结果:DM中存在MxA肌浆表达(94.4%,17/18),活动性狼疮肌炎(LM,80%,16/20),不活跃的LM(36%,4/11),抗合成酶综合征(ASYS,20%,2/10),系统性硬化症(13%,2/15),干燥综合征(7.7%,1/13),和人类免疫缺陷病毒(HIV)肌炎(5.6%,1/18),在免疫介导的坏死性肌病(IMNM,0/16)和羟氯喹肌病(0/5)。与所有其他肌肽相比,MxA肌浆表达对LM和DM的敏感性和特异性分别为84.6%(95%CI:69.5-94.1)和92.1(95%CI:83.6-97.0),分别,优于TRIs。MxA毛细血管表达是非特异性的。组织学上,35%的LM病例表现出独特的全束坏死性肌病模式。其余的LM病例与DM/ASys有显著的形态学重叠(20%),IMNM(20%),或多发性肌炎(15%)。
结论:MxA肌浆表达在LM和DM中非常普遍,是区分DM和LM与其他肌体的有用标记。LM可以表现为需要与DM区分的各种病理模式,IMNM,Asys,和多发性肌炎。
OBJECTIVE: Myxovirus resistance protein A (MxA) is a type I interferon (IFN1) pathway activation marker and MxA sarcoplasmic expression is currently recognized as a highly specific marker for dermatomyositis (DM). However, we have frequently observed endothelial tubuloreticular inclusions (TRI), another surrogate IFN1 activation marker, in a variety of overlap myositides. The aim of this study was to examine MxA expression in those myositides.
METHODS: We retrospectively performed MxA immunostaining on a wide range of myositides.
RESULTS: MxA sarcoplasmic expression was present in DM (94.4%, 17/18), active lupus myositis (LM, 80%,16/20), inactive LM (36%, 4/11), antisynthetase syndrome (ASyS, 20%, 2/10), systemic sclerosis (13%, 2/15), Sjogren\'s syndrome (7.7%, 1/13), and human immunodeficiency virus (HIV) myositis (5.6%, 1/18) and was absent in immune-mediated necrotizing myopathy (IMNM, 0/16) and hydroxychloroquine myopathy (0/5). The sensitivity and specificity of MxA sarcoplasmic expression for LM and DM combined compared with all other myositides were 84.6% (95% CI: 69.5-94.1) and 92.1 (95% CI: 83.6-97.0), respectively, and superior to TRIs. MxA capillary expression was nonspecific. Histologically, 35% of LM cases demonstrated a unique panfascicular necrotizing myopathy pattern. The remainder of the LM cases had significant morphological overlap with DM/ASyS (20%), IMNM (20%), or polymyositis (15%).
CONCLUSIONS: MxA sarcoplasmic expression is highly prevalent in LM and DM and is a useful marker in differentiating DM and LM from other myositides. LM can manifest in various pathology patterns that need to be differentiated from DM, IMNM, ASyS, and polymyositis.