There are multiple causes of leukocoria. The differential diagnosis
includes: persistent fetal vasculature (slide A), retinal detachment
(slide C), and congenital cataracts (slide D).
Of the causes of leukocoria, only retinoblastoma contains calcium (slide B), so calcium is an important clue to its diagnosis. On B-scan, these calcium deposits are seen as focal areas of high reflectivity. Slide B demonstrates an exophytic retinablastoma with multiple areas of calcium, which stain as dark purple on hematoxylin and eosin stain.
Other causes of leukocoria (not shown above) are: retinopathy of
prematurity, coloboma of choroid or optic disc, uveitis, toxocariasis,
and Coats disease.