An orbital pseudotumor may involve one or more structures within the orbit, which can be demonstrated on CT or other imaging studies.
Structures that may be involved alone or in combination:
(1) lacrimal gland
(2) extraocular muscle(s) - one or multiple
(3) fat - may be focal or diffuse
(4) orbital apex - may be a focal mass or diffuse
(5) globe - may involve Tenon's space and/or uvea-sclera
(6) optic nerve (optic neuritis) and/or perineural soft tissue (perineuritis)
(7) extra-orbital structures - cavernous sinus, intracranial structures
Special kinds:
(1) Tolosa-Hunt syndrome: apical involvement with extension into the cavernous sinus, usually with ophthalmoplegia
(2) sclerosing pseudotumor with diffuse involvement of all the orbital structures with fixation of the globe
