Retinoblastoma

Question 1

most common intraocular malignant tumor of childhood?

Answer 1

RB

Question 2

% bilaterality of RB?

Answer 2

30-40%

Question 3

genetic defect in RB?

Answer 3

mutation in RB1 tumor supressor gene located on long arm of chromosome 13. BOTH copies must be mutated for tumor to develop

Question 4

most common presenting signs of RB for patients younger than 5?

Answer 4

leukocoria (60%), followed by strabismus (20%) and ocular inflammation (5%)

Question 5

patient with bilateral retinoblastoma. what is the likelihood their child will have RB assuming spouse is unaffected

Answer 5

45% (and of these, 85% will be bilateral: Extremely high likelihood that this patient has a germline mutation, meaning 50% chance of passing on abnormal gene, and 90% penetrance. That means that 90% of the time, the other, previously normal RB gene will mutate (need two mutations for tumor development)

Question 6

chance of your offspring getting RB when you have unilateral RB?

Answer 6

7-15% (of these, 85% will be bilateral)

Question 7

If parents are unaffected, what is that chance that a child with RB will have bilateral disease?

Answer 7

33%

Question 8

Normal parents of a child with bilateral involvement. Chance of sibling having RB?

Answer 8

5%

Question 9

Most common presenting signs in RD for patients 5 and older?

Answer 9

Leukocoria (35%), decreased vision (35%), and strabismus (15%)

Question 10

Appearance of retinal vessels in RB compared to Coats?

Answer 10

normal in RB

Question 11

what type of RB tumors are more apt to causing vitreous seeds?

Answer 11

endophytic

Question 12

most common sites for RB mets?

Answer 12

Skull bones, distal bones, brain, spinal cord, lymph nodes. Generally spread by direct extension into optic nerve or through sclera.

Question 13

small, smooth, white, glistening tumor of retina, in some cases larger and calcified with a mulberry appearance

Answer 13

retinal astrocytoma

Question 14

What does the Reese-Ellsworth classification of RB predict?

Answer 14

eye survival (not vision, and not patient survival)

Question 15

What factors are considered in the International Classification System for Response to Chemotherapy?

Answer 15

size, subretinal fluid, vitreous seeding

(and the following are considered as features as an unsalvageable eye: tumor in ciliary body or anterior segment, neovasc glaucoma, vit heme, phthisis, orbital-cellulitis-like presentation)

Question 16

what test(s) should be ordered in all patients diagnosed with RB?

Answer 16

MRI brain with and w/o contrast (to rule out intracranial involvement)

Question 17

what additional tissue is affected in trilateral retinoblastoma?

Answer 17

pineal gland

Question 18

Four most important prognostic features of RB?

Answer 18

extraocular extension (most important), optic nerve involvement, choroidal invasion > 3mm (up for debate), trilateral involvement

Question 19

In the Western world, what is the survival rate of RB contained in the eye? With extraocular spread?

Answer 19

95%

less than 50%

Question 20

most common second malignancies in RB patients outside the field of radiation?

Answer 20

osteosarcoma, fibrosarcoma, soft tissue sarcoma

Question 21

most common second malignancies in RB patients inside the field of radiation?

Answer 21

osteosarcoma, melanoma, pinealoma, Ewing sarcoma, papillary thyroid carcinoma

Question 22

ultrasound finding in RB to differentiate from other causes of leukocoria?

Answer 22

focal areas of high reflectivity (from calcium, which is much more common in RB than other causes of leukocoria)