Lipomas of the internal auditory canal.

Intracranial lipomas are rare tumors which may occur in the cerebellopontine angle (CPA) or internal auditory canal (IAC). Although seemingly innocuous in other parts of the body, lipomas within the CPA and IAC often involve the surrounding cranial nerves, making attempts at hearing conservation largely unsuccessful. In an attempt to differentiate the IAC lipoma from the more commonly found acoustic schwannoma, the preoperative imaging studies (magnetic resonance and computerized tomography) on five previously unreported cases of IAC lipomas were evaluated. Based on these studies, features were determined that may allow the surgeon to diagnose IAC lipomas preoperatively. These features will be discussed, as well as the surgical and pathological findings.