Computerized axial tomography in inflammatory pseudotumor of the orbit.

Although thyrotoxicosis and orbital complications of acute ethmoid or frontal sinusitis are among the most common causes of unilateral exophthalmos, inflammatory pseudotumor is frequently accompanied by progressive acute unilateral proptosis. Because the associated chemosis, scleral erythema, and ophthalmoplegia constitute a spectrum of clinical findings present in numerous inflammatory orbital disorders and systemic diseases, the diagnosis of inflammatory pseudotumor is one of exclusion, often requiring orbital biopsy. Four patients without evidence of sinusitis, endocrinopathy, collagen vascular disease, or Wegener's granulomatosis are described. The diagnosis of orbital pseudotumor was disclosed by computed axial tomography, thus avoiding orbitotomy. The finding of scleral and choroidal thickening with enhancement following intravenous contrast injection represents a select group of patients with orbital pseudotumor and differentiates them from patients with endocrine exophthalmopathy or neoplasms. This noninvasive technique is extremely valuable because early diagnosis is critical for successful treatment. All four patients responded dramatically to high-dose corticosteroid therapy. In the absence of significant clinical response, however, Wegener's granulomatosis, lymphoma, and rhabdomyosarcoma, especially in younger patients, must be carefully excluded. Orbital exploration or decompression or both are used when proptosis, headache, or orbital pain does not resolve promptly, visual acuity deteriorates, or the diagnosis remains unknown.