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.