The differential diagnosis of orbital calcification as detected on computed tomographic scans.

We reviewed 350 orbital computed tomographic scans to determine the frequency, significance, and differential diagnosis of calcified lesions. Of 171 suitable scans that fulfilled the study criteria, 37 (22%) showed calcific densities. The most common intraocular lesion that contained calcium was retinoblastoma, and the most frequently calcified extraocular masses were vascular lesions (hemangioma, lymphangioma, and varix). We describe two orbital tumors--metastatic colonic carcinoma and primary orbital malignant melanoma--that previously have not been reported as having calcification. The presence of calcification within lesions of the lacrimal gland fossa usually, but not always, portends malignant disease.