Pannus / Retroodontoid pseudotumor

Retro-odontoid pseudotumors or pannus are deposits – mostly in the area behind the dens – resulting from instability. It is an indirect sign of instability.

There are different biochemical structures which form a pannus:

– Micro-hemorrhages
– Ossification
– Deposits of calcium pyrophosphate dihydrate (crowned dens syndrome)

Depending on the composition of the pannus, it looks different in the MRI.