Lipomas of the Internal Auditory Canal and Cerebellopontine Angle

Objective: To describe the presentation and clinical course of internal auditory canal (IAC) and cerebellopontine angle (CPA) lipomas. Design: Retrospective chart review at a single tertiary referral center. Methods: All patients presenting with an IAC or CPA mass radiographically consistent with a lipoma on high-resolution magnetic resonance imaging (MRI) were identified. Data including presenting symptomatology, tumor characteristics, management strategy, and patient course were collected. Results: Between 1996 and 2012, 19 patients were evaluated and diagnosed with a CPA/IAC lipoma. Four patients with incomplete medical record data were excluded. The mean age of the remaining 15 patients was 43.4 years, and the average duration of follow-up was 4.3 years (range, 0.1–15.8 years). Eight lesions were isolated to the IAC, while seven involved the CPA (mean diameter 10.1 mm). The most common presenting symptoms were mild sensorineural hearing loss (40%) and tinnitus (33%); seven patients were diagnosed after incidental discovery on MRI. Fourteen patients were managed with observation, and 1 underwent subtotal resection at an outside facility resulting in incomplete facial nerve paralysis, severe sensorineural hearing loss, and lower cranial nerve dysfunction. Conclusion: While rare, lipomas should be included in the differential diagnosis when evaluating CPA and IAC lesions. Owing to a generally benign clinical course, and high morbidity associated with resection, microsurgery should be reserved for those patients with severe symptomatology or definite radiographic progression. Careful radiological evaluation is critical to establishing an accurate diagnosis to prevent unnecessary morbidity associated with resection.