BACKGROUND Hypertrophic pachymeningitis (HP) is a rare disorder that involves localized or diffuse thickening of the dura mater. HP is associated with various inflammatory, infectious, and malignant diseases, such as rheumatic arthritis, sarcoidosis, anti-neutrophil cytoplasmic antibody-associated vasculitis, IgG4-related disorders, syphilis, tuberculosis, bacterial and fungal infections, cancer, and idiopathic diseases, when evaluation fails to reveal a cause. Among them, chronic infection with Propionibacterium acnes is a rare etiology of HP, and its pathology remains unclear. CASE PRESENTATION An 80-year-old man having refractory otitis media with effusion of the right ear presented with progressive right-sided headache and nausea. Post-contrast brain magnetic resonance imaging revealed right mastoiditis and remarkable thickening of the dura mater and enhancement of pia mater extending from the right middle cranial fossa to the temporal lobe. HP secondary to middle ear infection was suspected, and a biopsy of the right mastoid was performed. An anaerobic culture of the biopsied right mastoid showed the growth of P. acnes, and histopathological examination using P. acnes-specific monoclonal antibody (PAB antibody) revealed the infiltration of inflammatory cells with P. acnes. Moreover, using PAB antibody, P. acnes was detected in the biopsy specimen of the thickening dura mater. No granulomas were identified in either specimen. HP was resolved with long-term administration of antibiotics and steroids. CONCLUSION This is the first documentation of pathologically demonstrated chronic HP associated with P. acnes infection followed by refractory otitis media. This report showed that chronic latent P. acnes infection induces chronic inflammation.

中文翻译：

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痤疮丙酸杆菌相关的慢性肥厚性脑膜炎，然后是难治性中耳炎：一例病例报告。

背景技术肥厚性脑膜炎（HP）是一种罕见的疾病，涉及硬脑膜的局部或弥漫性增厚。HP与多种炎性，感染性和恶性疾病相关，例如风湿性关节炎，结节病，抗中性粒细胞胞浆抗体相关性血管炎，IgG4相关疾病，梅毒，结核病，细菌和真菌感染，癌症和特发性疾病评估无法揭示原因。其中，痤疮丙酸杆菌的慢性感染是HP的罕见病因，其病理仍不清楚。病例介绍一名80岁男子患有难治性中耳炎，右耳积液，伴有进行性右侧头痛和恶心。造影后脑磁共振成像显示右乳突炎，硬脑膜明显增厚以及从右中颅窝延伸至颞叶的脑膜增强。怀疑继发于中耳感染的HP，并进行了右乳突的活检。活检的右乳突的厌氧培养显示痤疮丙酸杆菌的生长，并且使用痤疮丙酸杆菌特异性单克隆抗体（PAB抗体）的组织病理学检查显示痤疮丙酸杆菌浸润了炎性细胞。此外，使用PAB抗体，在增厚硬脑膜的活检标本中检测到痤疮丙酸杆菌。在两个标本中均未发现肉芽肿。通过长期使用抗生素和类固醇可以解决HP。结论这是病理证实的慢性HP与痤疮丙酸杆菌感染相关的继发难治性中耳炎的第一份文献。该报告表明，慢性潜伏痤疮感染可诱发慢性炎症。