Background

Endomyocardial biopsy results are integral for diagnosis and management of myocarditis. Current diagnostic classifications of myocarditis are based on the microscopic and immunochemical characterization of inflammation do not include monocyte/macrophage-predominant (i.e. “histiocytic”) myocarditis as a histologic subtype.

Methods

Endomyocardial biopsies from 6 patients with sudden heart failure were reviewed by 3 cardiac pathologists. Routine stains and immunostains to identify T cells and monocytes/macrophages, complement C4d, and endothelium were applied. Electron microscopy was performed in 2 cases.

Results

The 6 patients included 2 with diagnoses of systemic lupus erythematosus (SLE) and 4 without known disease. Microscopy showed space-occupying inflammation in 2 cases and interstitial inflammation in 4. No giant cell myocarditis or eosinophilic myocarditis was found. Immunostains showed infiltration predominantly by macrophages and/or monocytes with markedly fewer T cells. In 4 of 6 cases necrotic cells were immunopositive for complement C4d. Monocytes we identified immunochemically within the microvasculature in 5 cases and by electron microscopy in 2. Patients with SLE had microvascular C4d positivity or interstitial/sarcolemmal staining. Clinical outcomes ranged from spontaneous resolution to persistent heart failure requiring an internal cardioverter/defibrillator.

Conclusions

(1) Heart failure with CD68 predominant inflammation (“histiocytic” myocardial inflammatory disease, HMID) occurs with variable clinical presentation and outcome; (2) HMID may be primary or secondary; (3) some cases of HMID show features suggestive of antibody and/or complement mediated myocardial injury, and (4) HMID is a diagnosis distinct from those in classification systems currently in use.

中文翻译：

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表现为暴发性心力衰竭的以巨噬细胞为主的炎性心肌病谱

背景

心内膜心肌活检结果对于心肌炎的诊断和治疗是不可或缺的。目前心肌炎的诊断分类基于炎症的显微镜和免疫化学特征，不包括以单核细胞/巨噬细胞为主的（即“组织细胞”）心肌炎作为组织学亚型。

方法

6 名突发性心力衰竭患者的心内膜心肌活检由 3 名心脏病理学家进行审查。应用常规染色和免疫染色来识别 T 细胞和单核细胞/巨噬细胞、补体 C4d 和内皮细胞。2例行电镜检查。

结果

6 名患者包括 2 名诊断为系统性红斑狼疮 (SLE) 和 4 名没有已知疾病。镜下显示占位性炎症2例，间质炎症4例。未发现巨细胞性心肌炎和嗜酸性心肌炎。免疫染色显示主要由巨噬细胞和/或单核细胞浸润，T 细胞明显减少。6 例中有 4 例坏死细胞对补体 C4d 呈免疫阳性。我们在 5 例中通过免疫化学方法在微血管系统内鉴定出单核细胞，在 2 例中通过电子显微镜鉴定出单核细胞。SLE 患者有微血管 C4d 阳性或间质/肌膜染色。临床结果范围从自发消退到需要内部心脏复律器/除颤器的持续性心力衰竭。

结论

(1) 以 CD68 为主的炎症（“组织细胞性”心肌炎性疾病，HMID）发生心力衰竭，临床表现和结果各不相同；(2) HMID可以是主要的也可以是次要的；(3) 一些 HMID 病例表现出提示抗体和/或补体介导的心肌损伤的特征，以及 (4) HMID 是一种不同于目前使用的分类系统的诊断。