Retinoblastoma

Question 1

What is retinoblastoma (RB)?

Answer 1

Retinoblastoma is a malignant tumour arising from primitive retinal cells before their final differentiation.

Question 2

What percentage of childhood cancers does retinoblastoma account for?

Answer 2

Retinoblastoma accounts for about 3% of all childhood cancers.

Question 3

How common is retinoblastoma in live births?

Answer 3

Retinoblastoma occurs in 1 in 15-20,000 live births.

Question 4

What is the mean age of presentation for heritable versus non-heritable retinoblastoma?

Answer 4

The mean age of presentation is under 12 months for heritable cases and around 24 months for non-heritable cases.

Question 5

At what age is retinoblastoma seldom seen and extremely rare?

Answer 5

Retinoblastoma is seldom seen after 3 years of age and is extremely rare after 6 years of age.

Question 6

What gene is associated with retinoblastoma?

Answer 6

The RB1 gene is associated with retinoblastoma.

Question 7

Where is the RB1 gene located?

Answer 7

The RB1 gene is located on chromosome 13q14.

Question 8

What percentage of retinoblastoma cases are heritable?

Answer 8

Heritable retinoblastoma accounts for 40% of all cases.

Question 9

What factors increase the risk of bilateral or multifocal retinoblastoma?

Answer 9

Advanced paternal age and the presence of 1 inherited mutant RB1 allele increase the risk of bilateral or multifocal retinoblastoma.

Question 10

What non-ocular malignancies are associated with heritable retinoblastoma?

Answer 10

Non-ocular malignancies associated with heritable retinoblastoma include pinealoma, osteosarcoma, and melanoma.

Question 11

How does non-heritable retinoblastoma differ from heritable retinoblastoma?

Answer 11

Non-heritable retinoblastoma is typically unilateral, non-transmissible, and does not predispose to second non-ocular cancers.

Question 12

What is the risk of retinoblastoma in siblings if the parents are unaffected versus affected?

Answer 12

If parents are unaffected, the sibling risk is 2%, but if the parents are affected, the risk increases to 40%.

Question 13

What is the most common clinical feature of retinoblastoma?

Answer 13

Leukocoria, or white pupil reflex, is the most common clinical feature of retinoblastoma.

Question 14

Which clinical feature is associated with raised intracranial pressure in trilateral retinoblastoma?

Answer 14

Features of raised intracranial pressure, such as proptosis, are associated with trilateral retinoblastoma.

Question 15

What are three differential diagnoses for leukocoria?

Answer 15

Three differential diagnoses for leukocoria include congenital cataract, persistent anterior foetal vasculature, and Coats disease.

Question 16

Which imaging modality is preferred in heritable retinoblastoma and why?

Answer 16

MRI is preferred in heritable retinoblastoma as CT scans increase the risk of orbital tumours.

Question 17

What is the primary goal of retinoblastoma management?

Answer 17

The primary goal of management is to save life.

Question 18

What is the preferred treatment for small tumours up to 3mm in diameter?

Answer 18

Small tumours up to 3mm are treated with laser photocoagulation, transpupillary thermotherapy, or cryotherapy for pre-equatorial tumours.

Question 19

How are medium-sized tumours up to 12mm in diameter treated?

Answer 19

Medium-sized tumours up to 12mm in diameter are treated with brachytherapy, chemotherapy, and, in some cases, external beam radiotherapy (EBR).

Question 20

When is enucleation indicated in retinoblastoma management?

Answer 20

Enucleation is indicated if there is rubeosis iridis, vitreous haemorrhage, optic nerve invasion, or if chemotherapy fails.

Question 21

What are the treatment options for metastatic retinoblastoma?

Answer 21

Metastatic retinoblastoma is treated with high-dose chemotherapy, intrathecal chemotherapy, myeloablative therapy, and radiotherapy.

Question 22

How often should a heritable retinoblastoma case be followed up after treatment?

Answer 22

Heritable retinoblastoma should be followed up monthly for the first year after treatment.