Orbital pseudotumor, differential diagnosis.

A 66-year-old white male presented with complaints of redness of his left eye, blurred vision, lid edema, and an intermittent throbbing pain above his left eye for 4 days. Significant clinical findings included mild hyperemia and edema of the left upper lid, marked engorgement and tortuosity of the conjunctival and episcleral vessels, mild chemosis, and extreme limitation of the extraocular movements of the left eye in all directions of gaze, especially adduction. This eye also showed a measurable proptosis with positive retropulsion. Pupillary responses and color vision were normal in both eyes. A CT scan revealed an enlarged medial rectus muscle, including its tendinous insertion with a normal cavernous sinus. On the basis of the clinical findings and the CT scan, a diagnosis of orbital pseudotumor was made. The patient was treated with high dose systemic prednisone, which resulted in a dramatic improvement of symptoms and signs.