Doughnut sign (orbit)

Last revised by Daniel J Bell on 27 Apr 2020

The doughnut sign of optic nerve sheath meningioma refers to the appearance of this tumor on coronal CT/MRI. The meningioma forms a thick cuff of enhancing tumor around the central non-enhancing optic nerve, mimicking the appearance of a ring doughnut. It is the coronal equivalent of the tram-track sign.

Neither the tram-track sign, nor - by extension - the doughnut sign appearance of the optic nerve, are by any means pathognomonic 2

Other described causes of this sign include 2,3:

History and etymology

The doughnut sign of optic nerve sheath meningioma was first described, on CT, in 1983 1.

See also

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