Leukocoria and retinoblastoma: Case

Framing the case

This fourteen-month-old boy has the classic presentation of an intraocular retinoblastoma detected by the parent and confirmed by the red reflex test. The white glow in the flash photograph, the cream-white reflex on the left and the normal orange-red on the right together make the leukocoria, and the framework that organises the case is the urgent referral, the RB1 tumour suppressor gene and the International Intraocular Retinoblastoma Classification. The first priority is the same-day referral to the ophthalmology service, because the delay of the weeks can convert the curable intraocular tumour into the lethal extraocular disease. ^[1][2]

Confirming the diagnosis

The ophthalmology service performs the examination under anaesthesia with the indirect ophthalmoscopy, the fundus photography and the measurement of the tumour. The ocular ultrasound is the first-line imaging, and it shows the intraocular mass with the calcification that is the hallmark of the retinoblastoma and that distinguishes it from the Coats disease and the persistent fetal vasculature. The contrast-enhanced magnetic resonance imaging of the orbits and the brain defines the intraocular tumour, the optic nerve invasion, the extraocular extension and the pineal or the suprasellar mass of the trilateral retinoblastoma. The computed tomography is avoided because of the radiation and the second-malignancy risk in the heritable disease. ^[1][8]

The differential diagnosis

The retinoblastoma is distinguished from the long list of the leukocoria causes on the location and the associated features. The congenital cataract has the opacity within the lens itself, visible at the naked eye. The Coats disease is the retinal telangiectasia with the exudative detachment of the older boy, and it does not calcify. The persistent fetal vasculature carries the microphthalmia, the shallow anterior chamber and the retrolental fibrotic mass. The toxocariasis is the nematode granuloma of the older child exposed to the puppy, and the retinal coloboma is the sectoral defect of the inferior retina. The intraocular calcification on the ultrasound settles the question in favour of the retinoblastoma. ^[1][3]