Pseudotumor of the orbit. Clinical, pathologic, and radiologic evaluation.

Pseudotumor, Graves' disease, and lymphoproliferative disease are the most common ophthalmologic disease entities requiring evaluation by CT and MR imaging. A history of acute onset, pain, swelling, proptosis, and response to steroids are the classical findings. The radiologic findings are categorized according to location into dacryoadenitis, myositis, and sclerouveitis, with and without associated infiltrations. The inflammatory infiltrate, which is composed of polymorphic leukocytes, lymphocytes, and plasma cells interspersed with a variable amount of fibrovascular tissue, may be diffuse or localized. The preferred radiologic method used for assessment of pseudotumor is CT. MR imaging, however, is indicated for evaluation of the Tolosa-Hunt syndrome, which is characterized by an inflammatory infiltrate in the orbital apex and cavernous sinus leading to cranial nerve involvement with ophthalmoplegia. The clinical and radiologic constellation of findings allows a definitive diagnosis in most cases.