Differential diagnosis of leukokoria: radiologic-pathologic correlation

Leukokoria is an abnormal pupillary light reflection that usually results from an intraocular abnormality and is seen most often in children. One-half of the cases of childhood leukokoria are caused by retinoblastoma, a malignant tumor of immature retinoblasts that manifests in a normal-sized eye as a calcified mass, is often partially necrotic, and grows into the vitreous and through the choroid. Retinoblastoma enhances with contrast material and, unlike most tumors, may be darker than vitreous on T2-weighted images. When leukokoria is associated with microphthalmia, persistent hyperplastic primary vitreous (PHPV) (28% of cases) or retinopathy of prematurity (ROP) (5% of cases) should be considered. PHPV is a congenital, usually unilateral lesion that appears as a dense tubular mass extending from the lens to the retina along the course of the hyaloid canal. Hemorrhage from PHPV produces a subhyaloid (or subretinal) fluid collection, often with characteristic blood-fluid levels. ROP is bilateral and usually manifests in premature infants who received supplemental oxygen therapy. Coats disease (16% of leukokoria) is a sporadic unilateral idiopathic retinal telangiectasia that produces a lipoproteinaceous subretinal exudate leading to complete retinal detachment. The globe has normal size but increased attenuation and signal intensity from hemorrhage without calcification or enhancement. Toxocaral endophthalmitis (16% of leukokoria) is a granulomatous reaction to the parasite in the vitreous and uveoretinal coat. Retinal astrocytoma (3% of leukokoria), which manifests in a normal-sized globe, is an indolent benign neoplasm commonly associated with phakomatoses (usually tuberous sclerosis).