This case illustrates a right cerebellopontine angle (CPA) mass in an elderly patient. The two main differential diagnosis remain between meningioma and schwannoma. The tumor was resected by a retrosigmoid approach and confirmed as an acoustic schwannoma.
Most vestibular schwannomas have an intracanalicular component, and often result in widening of the porus acusticus resulting in the trumpeted IAM sign, which is present in up to 90% of cases. In a minority of cases (~20%), such in this one, they are purely extracanalicular, only abutting the porus acousticus 1.