Computed tomography in the diagnosis of retinoblastoma.

The role of orbital computed tomography (CT) in the management of retinoblastoma is reviewed. All 21 patients with retinoblastoma studied with high-resolution computed tomography had intraocular calcification demonstrable in at least one eye. 83% of tumours showed evidence of calcification on CT scan. The degree of calcification appeared to depend on tumour size; only small tumours were devoid of calcification. The amount and distribution of calcification was similar on both histological study and CT scan. In patients under 3 years old in whom a retinoblastoma is suspected the presence of calcification on CT is virtually diagnostic of it. Patients with leucocoria without calcification on CT probably have a simulating lesion.