Supplementary Material for: Intracranial Inflammatory Myofibroblastic Tumor: A Rare Case Report

Introduction: Inflammatory pseudotumor encompasses a broad range of non-neoplastic and neoplastic entities, including inflammatory myofibroblastic tumors (IMT). Because it is a rare mesenchymal tumor of unknown etiology and pathogenesis, and its clinical symptoms and radiologic features are not distinctive, intracranial IMT could be misdiagnosed as other extra-axial tumors. Here, we present a case of intracranial IMT suspected to be a brain abscess. Case Presentation: In this case, a 73-year-old woman presented headaches, nausea, and vertigo. Brain computed tomography (CT) and magnetic resonance imaging (MRI) showed 4 x 3 cm sized oval rim-enhanced lesion on the left cerebellopontine angle. Considering the patient’s history of otitis media and CT findings, we hypothesized that this lesion was a chronic brain abscess. The initial burr hole drain surgery was unsuccessful because there was no abscess, leading to a second radical excision surgery. Histopathological and immunohistochemical analyses eventually revealed a final diagnosis of intracranial IMT. Conclusion: Intracranial IMT is a rare disease with unknown pathogenesis. Diagnosis primarily depends on histopathological and IHC analyses. As observed in our case, this disease may be mistaken for meningiomas, solitary fibrous tumors, or chronic abscesses due to its rare occurrence.

引言：炎症性假瘤涵盖了广泛的非肿瘤性与肿瘤性病变范畴，其中包括炎性肌纤维母细胞瘤（Inflammatory Myofibroblastic Tumor，IMT）。由于该病属于病因及发病机制均未明确的罕见间叶源性肿瘤，且临床症状与影像学特征缺乏特异性，颅内IMT极易被误诊为其他轴外肿瘤。本文报告1例被误诊为脑脓肿的颅内IMT病例。

病例报告：本例患者为73岁女性，因头痛、恶心及眩晕就诊。脑计算机断层扫描（computed tomography，CT）与磁共振成像（magnetic resonance imaging，MRI）结果显示，左侧桥小脑角区存在一枚4×3 cm大小的椭圆形环形强化病灶。结合患者中耳炎病史与CT影像学表现，我们初步推测该病灶为慢性脑脓肿。首次实施的颅骨钻孔引流术因未发现脓肿而失败，随后患者接受了二次根治性切除术。最终通过组织病理学与免疫组织化学（immunohistochemistry，IHC）分析，确诊为颅内IMT。

结论：颅内IMT是一种发病机制未明的罕见疾病，其诊断主要依赖组织病理学与IHC分析。正如本次病例所见，由于该病发病率极低，易被误诊为脑膜瘤、孤立性纤维瘤或慢性脓肿。