Retinoblastoma
Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management
Definition
Retinoblastoma is a rare, malignant tumour of the retina occurring predominantly in children, arising from mutations in the RB1 tumour suppressor gene.
Aetiology
- Genetic mutation: biallelic inactivation of the RB1 gene.
- Hereditary form: autosomal dominant inheritance with early onset and bilateral involvement.
- Sporadic form: unilateral and later onset.
Pathophysiology
- Mutation of the RB1 gene disrupts cell cycle regulation, leading to uncontrolled proliferation of retinal cells.
- Tumour growth can extend into the vitreous, optic nerve, and beyond the eye.
- Metastasis may occur via direct extension or haematogenous spread.
Risk Factors
- Family history of retinoblastoma.
- Heritable RB1 gene mutations.
- Parental exposure to radiation.
Signs and Symptoms
- Leukocoria: abnormal white pupillary reflex.
- Strabismus: misalignment of the eyes.
- Reduced vision: due to retinal involvement.
- Orbital inflammation: in advanced cases.
Investigations
- Ophthalmic examination: under anaesthesia if necessary.
- Ocular ultrasound: identifies calcifications within the tumour.
- MRI of the orbits and brain: assesses local extension.
- Genetic testing: determines hereditary involvement.
Management
1. Conservative Management:
- Ongoing surveillance in hereditary cases.
2. Medical Management:
- Systemic chemotherapy: reduces tumour size before local treatment.
- Intra arterial chemotherapy: targeted delivery to the ophthalmic artery.
- Intravitreal chemotherapy: for vitreous seeding.
3. Surgical Management:
- Enucleation: for advanced, non salvageable tumours.
4. Referral:
- Ophthalmology: urgent referral for suspected cases.
- Oncology: for systemic management.
- Genetics: if hereditary disease is suspected.