RB

Question 1

What is the most common intraocular tumor of childhood?

Answer 1

Retinoblastoma (RB).

Question 2

What is the best diagnostic clue for retinoblastoma on imaging?

Answer 2

An intraocular calcified mass in a child.

Question 3

What is the most common presenting sign of retinoblastoma?

Answer 3

Leukocoria (white pupil) in 50-60% of cases.

Question 4

What is the typical age range for diagnosis?

Answer 4

90-95% of cases are diagnosed by age 5 years.

Question 5

What are the two types of retinoblastoma genetics?

Answer 5

Sporadic (nongermline, 60% of RBs) and inherited (germline, 40% of RBs).

Question 6

What is the definition of trilateral retinoblastoma?

Answer 6

Bilateral ocular RB plus a midline intracranial neuroblastic tumor, typically a pinealoblastoma.

Question 7

What is the role of CT in diagnosing retinoblastoma?

Answer 7

CT is useful for detecting calcification, which is present in over 90% of RBs.

Question 8

What is the characteristic signal of RB on T2-weighted MR?

Answer 8

Moderate to marked hypointensity relative to the vitreous.

Question 9

What is the characteristic signal of RB on T1-weighted MR?

Answer 9

Mild hyperintensity relative to the vitreous.

Question 10

How does retinoblastoma appear on contrast-enhanced MR?

Answer 10

As a moderately to markedly heterogeneous enhancing mass.

Question 11

What is a poor prognostic indicator for retinoblastoma?

Answer 11

Extraocular extension, which occurs in less than 10% of cases.

Question 12

How does invasion of the optic nerve affect prognosis?

Answer 12

Survival decreases with increasing nerve involvement, from 90% for superficial invasion to 60% for postlaminar invasion.

Question 13

What is the most common extraocular site of spread for retinoblastoma?

Answer 13

Along the scleral vessels into the orbit and along the optic nerve to the subarachnoid space.

Question 14

What are the four growth patterns of retinoblastoma?

Answer 14

Endophytic (inward protrusion into the vitreous), exophytic (outward growth into the subretinal space), mixed, and diffuse infiltrating.

Question 15

What is a key feature of the endophytic growth pattern?

Answer 15

It is associated with vitreous seeding.

Question 16

What is a key feature of the exophytic growth pattern?

Answer 16

It is associated with retinal detachment and subretinal exudate.

Question 17

What is the name of the microscopic finding characteristic of retinoblastoma?

Answer 17

Flexner-Wintersteiner rosettes and fleurettes.

Question 18

What is the role of MR in assessing retinoblastoma?

Answer 18

It is used to assess the extent of intraocular, optic nerve, orbital, and intracranial involvement.

Question 19

What is a differential diagnosis for a hyperdense globe with a normal size and no calcification?

Answer 19

Coats disease.

Question 20

What is a differential diagnosis for a small globe with no calcification but hyperintense T2 signal?

Answer 20

Persistent hyperplastic primary vitreous (PHPV).

Question 21

What are some risk factors for metastatic disease in retinoblastoma?

Answer 21

Involvement of the optic nerve, choroid, anterior chamber, or orbit.

Question 22

What is the significance of enhancement of the anterior eye segment on MR?

Answer 22

It reflects neoangiogenesis and is associated with more aggressive tumor behavior.

Question 23

What is the typical age of diagnosis for unilateral versus bilateral retinoblastoma?

Answer 23

Unilateral: 24 months; bilateral: 13 months.

Question 24

What are some associated abnormalities in patients with germline retinoblastoma?

Answer 24

An increased risk of a second malignancy, such as sarcoma, melanoma, or CNS tumors.

Question 25

What is the role of ultrasonography (US) in retinoblastoma?

Answer 25

B-scan shows an echodense, irregular mass with focal shadows, and A-scan shows highly reflective spikes at calcifications.

Question 26

What is the primary treatment for advanced retinoblastoma with no chance to preserve useful vision?

Answer 26

Enucleation.

Question 27

What is the currently favored first-line therapy for lower-grade intraocular tumors?

Answer 27

Chemotherapy (chemoreduction).

Question 28

What is the prognosis for trilateral disease?

Answer 28

Less than 24-month survival.

Question 29

What is the role of the Reese-Ellsworth and International Classification (ICRB) systems?

Answer 29

Reese-Ellsworth is more useful for radiation therapy management, while ICRB is more useful for chemotherapy management.

Question 30

What is the relationship between germline retinoblastoma and family history?

Answer 30

A positive family history is present in only 5-10% of cases, as new germline mutations account for 30-35% of cases.

Question 31

What is the function of the RB1 gene?

Answer 31

It codes for the pRB tumor suppressor protein, which regulates cell growth, division, and apoptosis.

Question 32

What is a key clinical feature that may indicate anterior chamber enhancement on MR?

Answer 32

Rubeosis iridis (redness of the iris secondary to neovascularization).

Question 33

How can RB rarely mimic inflammatory disease?

Answer 33

In its diffuse infiltrating form, which is plaque-like and often lacks calcification.

Question 34

What is the risk of a second malignancy in nonirradiated versus irradiated patients with germline disease?

Answer 34

20-30% in nonirradiated patients and 50-60% in irradiated patients.

Question 35

What is the key role of MR after surgery for retinoblastoma?

Answer 35

To evaluate for recurrent intraorbital tumor, particularly along the optic nerve and chiasm.

Question 36

What are some causes of leukocoria besides RB?

Answer 36

Persistent hyperplastic primary vitreous, Coats disease, retinopathy of prematurity, and orbital toxocariasis.

Question 37

What is the prognosis for a patient with involvement at the surgical margin?

Answer 37

< 20% 5-year disease-free survival.

Question 38

How is retinoblastoma managed?

Answer 38

Treatment is based on tumor volume, localization, intraocular tumor extension, and extraocular stage of disease.

Question 39

What are the typical gross pathological features of RB?

Answer 39

A yellowish-white irregular pedunculated retinal mass.

Question 40

What is the incidence of retinoblastoma?

Answer 40

Approximately 1 in 17,000 live births.

Question 41

What is the purpose of T2-weighted MR in diagnosing RB?

Answer 41

It helps distinguish RB from other hyperintense lesions and is the best sequence for subretinal fluid and vitreous hemorrhage.

Question 42

What is the relationship between inherited disease and tumor laterality?

Answer 42

Inherited RB is associated with all bilateral and multilateral disease, but a minority of unilateral cases (15%) are also inherited.

Question 43

How can you differentiate a unilateral from a bilateral RB?

Answer 43

Unilateral disease is more common (60%), while bilateral is less common (40%).

Question 44

What is the difference between a bilateral and a trilateral retinoblastoma?

Answer 44

Bilateral RB is confined to both eyes, while trilateral RB includes a midline intracranial tumor.

Question 45

How is choroidal invasion assessed on MR?

Answer 45

By localized thickening and heterogeneous contrast enhancement near the tumor.

Question 46

How is scleral invasion assessed on MR?

Answer 46

By an interruption in the thin, hypointense zone surrounding the enhancing choroid.

Question 47

How is optic nerve invasion assessed on MR?

Answer 47

By thickening of the optic disc (prelaminar) and enhancement of the nerve (postlaminar).

Question 48

Why is there a discrepancy between MR and histology for optic nerve invasion?

Answer 48

MR has a low sensitivity and specificity for assessing optic nerve invasion.

Question 49

What is a key feature of RB on axial CECT?

Answer 49

A right ocular mass with heterogeneous enhancement and a dense component in the posterolateral portion of the globe consistent with calcification.

Question 50

What are the clinical findings of an advanced case of untreated RB?

Answer 50

Striking leukocoria and proptosis.

Question 51

What does a hypointense mass filling much of the vitreous compartment on T2 FS MR suggest?

Answer 51

Retinoblastoma.

Question 52

What is the significance of globe size in RB?

Answer 52

Eyes containing RB may be smaller than the contralateral normal eye.

Question 53

What are the two classification systems for RB?

Answer 53

Reese-Ellsworth and the International Classification of Retinoblastoma (ICRB).

Question 54

What is the goal of modern retinoblastoma treatment?

Answer 54

To cure the child (with a >95% cure rate) while preserving the eye and vision.

Question 55

What are some local treatment modalities for RB?

Answer 55

"Plaque radiotherapy, cryotherapy, and photocoagulation