What is the diagnosis for a child presenting with leukocoria (absent red reflex) in one eye, who is otherwise developing normally?

Retinoblastoma Until Proven Otherwise

In a 6-week-old infant presenting with unilateral leukocoria (absent red reflex), retinoblastoma must be assumed as the diagnosis until proven otherwise, and this child requires urgent ophthalmologic evaluation within 24-48 hours. 1, 2

Why Retinoblastoma is the Primary Concern

• Retinoblastoma accounts for approximately 50% of all leukocoria cases in infants, making it the single most common cause in this age group, and represents a life-threatening malignancy that requires immediate exclusion. 3, 4

• The American College of Radiology explicitly states that retinoblastoma should be considered the most likely diagnosis in a 6-week-old infant with unilateral leukocoria. 1

• Normal developmental milestones do NOT exclude retinoblastoma—both retinoblastoma and congenital cataract can present with normal systemic development while causing severe unilateral visual impairment. 5

Why Not Congenital Cataract (Option C)?

While congenital cataract is the most common cause of leukocoria overall (35% of cases), this statistic includes all age groups. 6

• In the specific context of a 6-week-old infant, retinoblastoma becomes proportionally more likely and must be excluded first due to its life-threatening nature. 1, 2

• The clinical approach is identical regardless: both conditions require urgent ophthalmologic referral, and the ophthalmologist will definitively differentiate between them using fundoscopy, ocular ultrasound, and imaging. 5

• Congenital cataract typically shows absence of calcification on imaging, which helps distinguish it from retinoblastoma. 1

Why Not Toxocariasis (Option A)?

• Ocular toxocariasis is extremely uncommon at 6 weeks of age and typically presents in older children (usually toddlers and school-age children who have had environmental exposure to contaminated soil). 1

• Toxocariasis represents only 16% of leukocoria cases overall and is exceedingly rare in the neonatal period. 4

Critical Action Required

This is an ophthalmologic emergency—do not delay referral while attempting outpatient workup. 1, 2

• The absence of a red reflex on examination is an absolute indication for urgent specialist evaluation. 5, 7

• The ophthalmologist will perform:

  • Fundoscopic examination under dilation 5
  • Ocular ultrasound (B-scan) to characterize intraocular pathology and detect calcifications 5
  • MRI of head and orbits with and without IV contrast if retinoblastoma is confirmed, to evaluate for optic nerve infiltration and intracranial spread 8, 1

Common Pitfall to Avoid

Never assume the diagnosis is benign simply because the child is developing normally—this false reassurance can lead to catastrophic delays in diagnosing retinoblastoma. 5