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White pupil (leukocoria) and retinoblastoma
A white pupil in a child is retinoblastoma until proven otherwise — the commonest malignant intraocular tumour of childhood, arising from loss of both copies of the RB1 gene — so any absent or white red reflex, and also new strabismus, requires urgent referral to an ophthalmologist.
Why it matters in the exam
In the exam the parents report that in a flash photograph one eye looks white. Leukocoria is the commonest sign of retinoblastoma (about 60%), and the second is strabismus (about 20%). The mean age at diagnosis is about two years, and in bilateral disease earlier, around one year. About 40% of cases are heritable (germline mutation): all bilateral cases and a minority of unilateral ones, inherited in an autosomal dominant pattern with high penetrance. The gene is on chromosome 13 (13q14), and Knudson described the "two-hit" model.
Diagnosis is clinical by fundus examination under anaesthesia, with ultrasound showing calcification and MRI of the orbits and brain to exclude spread to the optic nerve and the pineal gland ("trilateral retinoblastoma"). No biopsy is done, and CT is avoided in heritable disease because of radiation. Treatment: intra-arterial or systemic chemotherapy, focal treatment (laser, cryotherapy), intravitreal melphalan, and removal of the eye (enucleation) for advanced unilateral tumours. Survival in high-income countries is above 95%.
Mutation carriers have a risk of second tumours — osteosarcoma, soft tissue sarcoma and melanoma — even higher after radiation, so external beam radiotherapy has almost been abandoned. The differential diagnosis of a white pupil: Coats disease (boys, unilateral, telangiectasia and yellow exudate), persistent fetal vasculature (small eye, unilateral), Toxocara, advanced ROP and congenital cataract. Siblings and offspring of a patient with a mutation need genetic testing and repeated fundus screening. The paediatrician finds most cases: a red reflex test in a dark room, both eyes together, at every visit in the early years, and taking seriously every parent who reports an "eye that looks strange" in photos or an eye that drifts.
Key points
- White pupil = retinoblastoma until proven otherwise.
- RB1 on chromosome 13; about 40% heritable.
- Leukocoria about 60%, strabismus about 20%.
- Clinical diagnosis with MRI and ultrasound, no biopsy.
- Carriers: risk of osteosarcoma and second tumours.
Summary table
| Condition | Clues | Distinction from retinoblastoma |
|---|---|---|
| Retinoblastoma | Age two, calcification on ultrasound | White vascular tumour, RB1 |
| Coats disease | Boy, unilateral, telangiectasia | Yellow exudate, no calcification |
| Persistent fetal vasculature | Small eye from birth | Fetal vascular remnant from disc to lens |
| Toxocara | Older child, contact with dogs | Granuloma, inflammation |
| Congenital cataract | Lens opacity from birth | The lens is opaque, the retina normal |
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Sources
- AAO Basic and Clinical Science Course, Section 4: Ocular Pathology and Intraocular Tumors, 2024-2025 — Retinoblastoma
- AAP Clinical Report: Red Reflex Examination in Neonates, Infants, and Children, 2022 — Technique and referral
- Kanski's Clinical Ophthalmology, 9th edition (2020) — Ocular tumours
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.