retinoblastoma

Question 1

Secondary malignancies seen in heritable Rb

Answer 1

Top 3: osteo, STS, melanoma

Rads field: osteo, fibrous histioma, leiomyosarcoma, angiosarcoma, RMS, PNET, meningioma, glioma

Non-rads: Osteo, RCC, Ewings, Medullo, melanoma, Hodgkin’s

Question 2

Which mutations are seen in Rb

Answer 2

99% Rb1

1% Myc-N - unilateral

Question 3

Presenting symptoms of Rb

Answer 3

Leukocoria
strabismus
nystagmus
buphthalmos
glaucoma
periorbital cellulitis
proptosis
mets

Question 4

Diagnostic w/u

Answer 4

EUA
U/S of eye
MRI orbits + brain 
Bone scan/BM/CSF only if high risk histology or extra-ocular Rb
Genetic consult

Question 5

Differential diagnosis

Answer 5

Congenital cataracts
Coat's
Persistent fetal vasculature
retinitis - toxo
medulloepithelioma (tumor of ciliary pigment)
astrocytic hamartoma
choroidal osteoma

Question 6

Describe classification of eye

Answer 6

A - small <3mm and away from foveola and optic disc

B - all remaining tumors confined to retina

C- local subretinal or vitreous seeding

D - diffuse seeding

E - more than 2/3 globe filled with tumor

Question 7

Describe staging system

Answer 7

0 - Not enucleated.

1 - Enucleated. CR

2- Enucleated. Microscopic residula

3 - Regional extension (orbital disease or pre-auricular/cervical LN)

4 - Mets (hematogenous, CNS)

Question 8

Chemotherapy options

Answer 8

Systemic:
- VCR/Carbo/Etop x 6 cycles (can drop Etop for grp B)

Intra-arterial:

• Melphalan
• Carbo, melphalan

Question 9

Focal therapy options

Answer 9

Cryotherapy
Thermotherapy
Photocoagulation
Brachytherapy

Question 10

Definition of high risk histology (post enucleation)

Answer 10

• massive choroidal replacement
• ciliary body infiltration
• iris infiltration
• sclearal invasion
• ant. chamber seeding
• post-laminar involvement (lamina cribrosa)

Question 11

What are the metastatic sites for Rb

Answer 11

Bone
BM
Liver
CNS

Question 12

Which Rb patients should be screened for germline Rb mutations?

Answer 12

Everyone!

- 15% unilaterals have germline Rb mutation

Question 13

What screening for offspring/sibs

Answer 13

HR: EUA Q4wk x 12 m, then Q8w, Q12w, Q6m

LR: EUA Q3-4m then Q6m

HR:

• Known Rb1 mutation in child,
• Positive FHx
• Sibling/offspring of survivor with BL Rb or UL with known Rb1 mutation.
• 90% penetrance for Rb+

Question 14

What is the ocular salvage rate for unilateral and bilateral RB

Answer 14

Unilateral: 75%

Bilateral: 65-75%

Question 15

Which syndrome is associated with Rb

Answer 15

13q deletion syndrome: microcephaly, dysmorphisms, mental retardation

Question 16

Risk of secondary malignancy in retinoblastoma

Answer 16

36-40% if Rb1 germline & radiation

15-20% if Rb1 germline

5% if no Rb1 germline