Serviço de Neurorradiologia, Hospital Dona Estefânia e São José, Centro Hospitalar Universitário de Lisboa Central, Lisboa
- Publicação sob a forma de poster electrónico XVI Congresso da SPNR Diagnóstica e Terapêutica, 19 e 20 novembro 2021, Lisboa
- Neuroradiology volume 64, pages1047–1076 (2022); doi.org/10.1007/s00234-022-02903-2
Introduction: Approximately 10% of all intracranial tumors occur in the cerebellopontine angle (CPA) and internal auditory canal (IAC). Up to 95% of these masses are vestibular schwannomas (VSs), and nearly all remaining cases are meningiomas. However, rare lesions that may mimic VSs have also been reported, such as non-vestibular schwannomas, hemangiomas, lipomas, lipochoristomas, inclusion cysts, metastases, primary adenocarcinomas, melanomas, and MALT lymphomas. Distinction from VSs is often not possible with preoperative imaging, and definitive diagnosis is only made by histopathology after surgery.
Methods and Results: We retrospectively searched our hospital database for patients with IAC masses (with or without CPA involvement), and selected cases of common and rare lesions, including presumably vestibular and facial schwannomas, meningioma, metastases, lipoma, and hemangioma. Some of these patients underwent surgical excision and had definitive histopathological diagnosis. Clinical data and CT/MR images were collected and discussed.
Discussion & Conclusion: Advances in neuroimaging have led to the detection of an increasing number of smaller tumors in the IAC, but VS and meningiomas still account for the vast majority of these. Other rare lesions may occur within or involve the IAC, and most of them are misdiagnosed preoperatively as VSs. Although definitive diagnosis is made by histopathological examination, there are some imaging clues and pitfalls that should not be missed by the neuroradiologist. Moreover, imaging plays an essential role in evaluating lesion size and extension, and mass effect on the adjacent structures, which is critical for treatment planning.
Keywords: differential diagnosis; internal auditory canal; neuroimaging