Osteoma of the Internal Auditory Canal

The use of MRI for the evaluation of lesions in the internal auditory canal presents a potential pitfall in the diagnosis of bony lesions of the IAC, because bone is poorly visualized with this method of imaging. The presence of marrow in an osteoma might aid in its detection, since fat in the marrow has a bright signal intensity of T1-weighted imaging. Computed tomography remains the imaging modality of choice for bony lesions of the temporal bone. We demonstrate a case of IAC osteoma in which surgical removal resulted in improvement of symptoms. The gross and microscopic appearance of the IAC osteoma in this case is similar to the characteristic findings of osteomas of the EAC. This suggests that the criteria applied to osteomas and exostoses of the EAC may also be used to differentiate bony lesions of the IAC.