Cholesterol granuloma, orbit

More common sites for a cholesterol granuloma include the petrous apex, middle ear and mastoid antrum. The lesion, when in the orbit, presents as an extraconal mass, in the superior-temporal quadrant. Differential diagnosis includes the lacrimal gland tumors. Although post-contrast T1-weighted scans are presented, the lesion was hyperintense pre-contrast (and specifically demonstrated only peripheral enhancement). Cholesterol granulomas (in more common locations, but as illustrated by this case) are known for their expansile nature, high signal intensity on T1- and T2-weighted scans, and peripheral dark hemosiderin rim on T2-weighted scans. The restricted diffusion (high SI on DWI, in this patient) is however more consistent with an epidermoid.

Cholesterol granuloma, orbit

Part of the on-line supplement to Neuroradiology – The Essentials with MR and CT (© 2015)