ABSTRACT
CONTEXT: Orbital pseudotumor (OP) is a benign inflammatory process of the orbit with a large polymorphous lymphoid infiltrate, associated with fibrosis in variable amounts, localized or diffuse. Graves' ophthalmopathy (GO) is the most common cause of proptosis, unilateral or bilateral. CASE REPORT: We report a patient with unilateral proptosis who was initially treated with antithyroid drugs for an euthyroid Graves disease, but the extension of the investigation infirmed this. The MRI findings (inflammation of fat, muscle and the left lacrimal gland) in conjunction with the biopsy infirmed the initial diagnostic and confirmed the OP. CONCLUSIONS: Orbital pseudotumor is a rare disorder that can image and clinically mimics some inflammatory disease especialy Graves' ophthalmopathy. Orbital MRI represents the most important test for diagnostic. A negative TRAb in euthyroid cases of proptosis can be a serious starting point for investigating an OP.
