Doughnut sign (orbit)

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:

• demyelinating optic neuritis
• sarcoidosis
• idiopathic orbital inflammation
• perioptic hematoma
• Erdheim–Chester disease
• leukemic infiltration of the optic nerve
• leptomeningeal metastases to the optic nerve ²

History and etymology

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

See also

• doughnut sign (disambiguation)