Retinoblastoma

Question 1

Retinoblastoma - overview

Answer 1

1. Def = rare childhood cancer arising from retina; most common primary intraocular malignancy of childhood
2. Sporadic and hereditary forms.
   - Sporadic = two separate mutations within a single retinoblast cell; always unilateral
   - Hereditary = one mutation in germ cell -> all retinoblasts descended from affected germ cell have first mutation -> by chance, more than one retinoblast will often develop -> hereditary form is often, but not always, bilateral
3. Sx (3+1) = leukocoria (white pupillary reflection; white tumour seen immediately behind lens), strabismus, poor vision; often fhx retinoblastoma
4. Ix (5)
   a. Dx = ophthalmoscope examination under anaesthesia
   b. Ocular ultrasonography
   c. MRI of brain and orbits
   d. Metastatic evaluation (bone marrow aspiration and biopsy, lumbar puncture, radionuclide bone scan) - but metastatic disease rarely present at time of dx
   e. Genetic testing - suggested for all affected parents
5. Mx (3)
   a. Low-risk tumours = cryotherapy, laser photocoagulation, plaque radiation therapy (less commonly)
   b. Moderate/high-risk = chemosurgery (selective destruction of tissue by use of chemicals), IV chemotherapy, enucleation (removal of eye)
   c. Metastatic disease = multimodal therapy (high-dose multiagent chemotherapy + radiotherapy + autologous haematopoietic stem cell rescue)