Differential diagnosis for causes of leukocoria
Leukocoria is defined as an abnormal white pupillary reflex. Retinoblastoma is the most concerning cause. Other causes include congenital cataract, infection (e.g., toxocariasis), persistent hyperplastic primary vitreous, retinopathy of prematurity, and Coats disease (fusiform dilation of retinal vessels, often with associated retinal detachment and subretinal exudate). Historical clues are helpful in differentiating these entities. The average age of patients with retinoblastoma is 13 months, whereas Coats disease generally occurs in boys older than 4 years old, and toxocariasis occurs after 6 years of age. The presence of calcification may aid in the diagnosis, because 95% of retinoblastomas contain calcium.