Presentation
Right sensorineural hearing loss. Presented for comparison with a previous MRI study 2 years ago.
Patient Data
Widening of the right internal auditory canal with internal fat density. No bone erosion.
Unremarkable left petrous bone.
A soft tissue lesion fills the entire right internal auditory canal extending from the porus acoustics to the fundus, having two components, each measuring 8 mm:
- the medial one showing low T1 signal with diffuse enhancement. No extension in the CPA cistern. It is associated with scalloping and flaring of the posterior canal wall
- the lateral (fundal) one shows fat signal with no enhancement. No intra-labyrinthine extension
Case Discussion
The current study shows no interval changes compared to a previous MRI study (not shown) with stationary size and MRI signals of right internal auditory canal lesions. The diagnosis was made based on imaging features alone. A combination of internal auditory canal lipoma and intracanalicular schwannoma is rare.
The suppression of signal on T1WI fat sat and no postcontrast enhancement confirm the presence of lipoma. In contrast to the adjacent lesion which shows homogeneous postcontrast enhancement and no suppression of T1WI fat sat which is likely a small intracanalicular schwannoma.
Although no line of cleavage between the two lesions is seen, they are considered different in nature. Fatty degeneration of schwannoma is reported in large schwannoma with the presence of fatty component inside the lesion.
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