Retinoblastoma

Around 4% of patients with the heritable type also have malignant midline neuroectodermal tumours, usually pineoblastoma. This is called trilateral retinoblastoma

Retinoblastoma can spread or metastasise from the eye to the brain, the CNS (brain and spinal cord) and the bones but this is rare in developed countries

About

• Embryonal tumour of the retina
• 1 in 18,000 live births.
• 3% of all cancers diagnosed in children.

Aetiology

• Inherit one copy of the RB gene
• RB gene is a tumour suppressor
• Retinoblastoma in eye(s) or pineal gland
• Increased risk of osteosarcoma x 50-500 times that of the general population
• Most heritable disease is bilateral and it is sometimes multifocal

Clinical

• Loss of red reflex in one or both eyes - leukocoria.
• Strabismus due to macular involvement
• Advanced disease with pain, glaucoma, or buphthalmos.
• 40% of cases are diagnosed in the first year of life.
• About 60% of all cases are unilateral.
• Incidence very low rate after 5 years of age.

Differentials

• Congenital cataract

Investigations

• Fundal eye examination with a maximally dilated pupil under GA and pineal
• Ocular USS and MRI
• Blood and tumour samples can be tested for a mutation in the Rb1 gene.

Staging Disease

• Group A: small tumours (3 mm across or less) that are only in the retina and are not near important structures such as the optic disc or the foveola.
• Group B: all other tumours (either larger than 3 mm or small but close to the optic disc or foveola) that are still only in the retina.
• Group C: well-defined tumours with small amounts spread under the retina (subretinal seeding) or into the vitreous (vitreous seeding).
• Group D: large or poorly defined tumours with widespread vitreous or subretinal seeding. The retina may have become detached from the back of the eye.
• Group E: the tumour is very large, extends near the front of the eye, is bleeding or causing glaucoma, or has other features that mean there is almost no chance the eye can be saved.
• Trilateral Rb typically develops between the ages of 20 and 36 months and has a poor prognosis, accounting for around half of mortality in the first ten years after diagnosis[4, 17].

Management

• In England urgent referral is made to one of two retinoblastoma hospitals in the UK - Birmingham Children's Hospital or the Royal London Hospital - for diagnosis and treatment.
• Photocoagulation, Cryotherapy, Transpupillary thermotherapy, Chemotherapy for large tumours.
• Plaque radiotherapy can be effective for small solitary tumours
• Systemic chemotherapy is used as an adjuvant in children previously considered candidates only for enucleation or bilateral external beam radiotherapy.
• Enucleation though this is much less common nowadays
• Ophthalmic artery chemotherapy using melphalan has shown some encouraging result

Screening

• Other children in family need screened until 5 yo