Presentation
56 year-old with vague right post auricular/occipital pain. History of sinus disease.
Patient Data
Combined sequences both performed within 3 days of each other initial study a routine NC brain
A circumscribed high T1 high T2 lesion is seen at the junction of sigmoid and transverse sinus on the right. It does not attenuate on fat suppressed sequences and no significant enhancement or restricted diffusion is seen.
In view of MRI findings CT mastoids performed
The bone adjacent to the lesion is irregular and it appears to likely have originated form the mastoid.
Concern following review of previous studies led to a CT venogram being performed.
Interestingly the lesion is of fat attenuation on CT.
Case Discussion
This is a difficult case. Although the lesion is of fat attenuation on all sequences and CT it does not attenuate on fat suppressed sequences, and as such cannot represent a lipoma, but must be 'fatty'.
The most likely diagnosis is thus an atypical (usually soft tissue attenuation on CT) cholesterol granuloma.
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