Cerebellopontine Angle and Internal Auditory Canal Lipomas: Case Series and Systematic Review

Cerebellopontine angle (CPA) and internal auditory canal (IAC) lipomas are rare, benign tumors comprising 0.08% of all intracranial tumors and can be mistaken for other, more common lesions of the CPA/IAC such as vestibular schwannoma. The purpose of this study was to review the literature and assess the evolution of CPA/IAC lipoma diagnosis and management. In addition, we present 17 new lipomas, matching the largest known case series of this rare tumor.

Retrospective case series and systematic review.

Systematic review of the literature was performed using PubMed and Google Scholar. References from identified articles were also reviewed to identify potential additional manuscripts. Manuscripts and abstracts were reviewed to identify unique cases. For the case series, the charts of all CPA/IAC lipoma patients seen at a single institution from 2006-2019 were manually reviewed. Logistic regression and chi-squared analysis were performed where appropriate.

A total of 219 unique lipomas have been reported in the literature, including 17 presented in this study. Surgical management has been performed in 46% of cases and has been conducted less often in recent decades, likely due to improved radiographic diagnostic capabilities and understanding of surgical outcomes. Surgical management is associated with worse neurologic outcomes (P = .002) and has become less common in recent decades. Although growth is unlikely, it has been demonstrated in patients into their 30s.

Accurate radiographic diagnosis is imperative for appropriate patient management, as CPA/IAC lipomas should typically be managed through observation and serial imaging whereas vestibular schwannomas and other CPA/IAC lesions may require microsurgical or radiosurgical intervention depending on growth and symptomatology. Laryngoscope, 131:2081-2087, 2021.