Download MBBS (Bachelor of Medicine, Bachelor of Surgery) Orthopaedics PPT 15 Retinoblastoma Lecture Notes
Retinoblastoma
Epidemiology
The most common primary intraocular malignancy of
childhood
3% of all childhood cancers
The second most common malignant intraocular tumour
1 in 18,000 live births
25-30% cases are bilateral but asymmetric
Survival rates are over 95% in specialized centers but are
much lower in the developing world.
Genetics & Histopathology
RB1 is the tumour suppressor gene in which
mutations/deletion predisposes to retinoblastoma.
Tumours are composed of small basophilic cells (retinoblasts)
with large hyperchromatic nuclei and scanty cytoplasm.
Characterized by the formation of structures known as
rosettes
Flexner?Wintersteiner,
Homer?Wright and fleurettes
Growth may be endophytic (into the vitreous) with seeding
of tumour cells throughout the eye, or
Exophytic (into the subretinal space) leading to retinal
detachment, or mixed, or the retina may be diffusely
infiltrated.
Optic nerve invasion may occur, with spread of tumour along
the subarachnoid space to the brain.
Metastatic spread is to regional nodes, lung, brain and bone.
Flexner?Wintersteiner Rosettes
Endophytic growth
Optic nerve infiltration
Types of retinoblastoma
1. Heritable (hereditary, germline) retinoblastoma accounts for
40%.
One of the pair of alleles of RB1 is mutated in all the cells in the body.
When a further mutagenic event (`second hit' according to the `two-hit'
hypothesis proposed by Knudson) affects the second allele, the cell may
then undergo malignant transformation.
Because of the presence of the mutation in all cells, a large
majority of these children develop bilateral and multifocal
tumours.
Pinealoblastoma (`trilateral retinoblastoma', which occurs in
up to 10%, usually before the age of 5),
Osteosarcomas,
Soft tissue sarcomas and melanomas
The risk of a second malignancy is about 6%
Increases five-fold if external beam
irradiation has been used to treat the original tumour,
The second tumour tends to arise within the irradiated field.
2. Non-heritable (non-hereditary, somatic) retinoblastoma.
60% Cases
The tumour is unilateral,
Non transmissible and
Does not predispose the patient to second non-ocular cancers.
If a patient has a solitary retinoblastoma and no positive
family history, Its very likely that
Non-heritable
The risk in each sibling and the patient's offspring is about
1%.
Screening of at-risk family members.
Siblings at risk of retinoblastoma should be screened by
Prenatal ultrasonography,
Ophthalmoscopy soon after birth and
Then regularly until the age of 4 or 5 years.
Early diagnosis correlates with a higher chance of preserving
vision, salvaging the eye and preserving life.
If a child has heritable retinoblastoma, the risk to siblings is
2% if the parents are healthy, and 40% if a parent is affected.
Parents should also be screened
Clinical features
Bilateral cases present with in 1 yr of age
Unilateral cases present up to 2 yrs of age
Leukocoria (white pupillary reflex) is the commonest
presentation (60%) and may first be noticed in family
photographs.
Leukocoria
Strabismus is the second most common (20%); fundus
examination is therefore mandatory in all cases of childhood
squint.
Painful red eye with secondary glaucoma
Painful red eye with uveitis
Poor vision.
Inflammation or pseudoinflammation
Nystagmus
Uveitis
Iris nodules with pseudohypopyon
Clinical features
Routine examination of a patient known to be at risk.
Orbital inflammation mimicking orbital or preseptal
cellulitis may occur with necrotic tumours
Orbital invasion or visible extraocular growth
Metastatic disease involving regional lymph nodes
and brain before the detection of ocular involvement is
rare.
Orbital cel ulitis
Orbital invasion
Signs
An intraretinal tumour
is a homogeneous,
dome-shaped white
lesion that becomes
irregular, often with
white flecks of
calcification.
Signs
An endophytic tumour
projects into the
vitreous as a white mass
that may `seed' into the
gel.
Signs
An exophytic tumour
forms multilobular
subretinal white
masses and causes
overlying retinal
detachment
Clinical Stages
I. Quiescent stage.
II. Glaucomatous stage.
III. Stage of extraocular extension.
IV. Stage of distant metastasis.
Clinical Stages
I. Quiescent stage.
Lasts for about 6 months to1year.
Leukocoria
Nystagmus
Strabismus
Diminution of vision
Retinal detachment
Clinical Stages
II. Glaucomatous stage.
Pain, redness, watering.
Eyeball is enlarged leading to
proptosis.
Conjunctival congesion.
Corneal haze.
Increased intraocular pressure.
Rarely acute iridocyclitis.
Clinical Stages
III. Stage of extraocular
extension.
Fungation and involvement
of extraocular tissues
resulting in marked
proptosis
Clinical Stages
IV. Stage of distant metastasis.
1. Lymphatic spread to preauricular and neighbouring lymph
nodes.
2. Direct extension by continuity to the optic nerve and brain
is common.
3. Metastasis by blood stream involves cranial and other
bones.
Investigations
Red reflex testing with a distant direct ophthalmoscope
Examination under anaesthesia
General examination
Tonometry.
Measurement of the corneal diameter
Anterior chamber examination
Ophthalmoscopy,
Cycloplegic refraction.
Investigations
Ultrasonography
Aqueous LDH levels
Wide field photography
CT scan
MRI for optic nerve evaluation
Bone scans and bone marrow aspiration
Genetic study
USG
B Scan displays a
caulifiower like mass
arising from the retina.
A scan through the mass
shows a characteristic V-Y
pattern.
CT SCAN
Differential diagnosis
Persistent anterior fetal vasculature (persistent
hyperplastic primary vitreous)
Coats disease
Retinopathy of prematurity
Toxocariasis
Uveitis
Vitreoretinal dysplasia
Endophthalmitis
Treatment
1. Tumour destructive therapy.
When tumour is involving less than half of retina and optic
nerve is not involved
Chemoreduction followed by local therapy
(Cryotherapy, thermochemotherapy or brachytherapy) for
large tumours (>12mm in diameter)
Tumour <12 mm in diameter and <8mm in thickness
Radiotherapy (external beam radiotherapy or brachytherapy)
combined with chemotherapy is recommended for medium
size.
Cryotherapy is indicated for a small tumour (<4.5 mm
indiameter and <2.5 mm in thickness) located anterior to
equator.
Laser photocoagulation is used for a small tumour located
posterior to equator <3 mm from fovea.
Thermotherapy with diode laser is used for a small tumour
located posterior to equator away from macula
2. Enucleation
Tumour involves more than half of the retina.
Optic nerve is involved.
Glaucoma is present and anterior chamber is involved.
Followed by radiotherapy and chemotherapy if optic nerve is
involved.
Intravenous carboplatin, etoposide and vincristine (CEV) are
given in three to six cycles according to the grade of
retinoblastoma.
Careful review at frequent intervals is generally required
following treatment, in order to detect recurrence or the
development of a new tumour, particularly in heritable
disease.
Palliative therapy
Retinoblastoma with orbital extension,
Retinoblastoma with intracranial extension, and
Retinoblastoma with distant metastasis.
Chemotherapy,
Surgical debulking of the orbit or orbital exentration, and
External beam radiotherapy
Prognosis
If untreated the prognosis is almost always bad and the
patient invariably dies.
Rarely, spontaneous regression with resultant cure and
shrinkage of the eyeball may occur due to necrosis followed
by calcification
Prognosis is fair (survival rate 70-85%) if the eyeball is
enucleated before the occurrence of extraocular extension.
MCQs
1. Gene Rb1 responsible for retinoblastoma is located at:
A. 13q14
B. 14q13
C. 13p14
D. 14p13
MCQs
2. Pathognomic feature of retinoblastoma is:
A. Necrosis
B. Calcification
C. Granulomatous reaction
D. None
MCQs
3. Characteristic histopathological feature of retinoblastoma is:
A. Flexner?Wintersteiner rosettes,
B. Granulomatous reaction
C. Homer?Wright and fleurettes
D. None
4. On A scan characteristic pattern of Retinoblastoma is:
A. Collar stud appearance
B. V-Y Pattern
C. Cauliflower pattern
D. All
5. The most common clinical presentation of retinoblastoma is:
A. Nystagmus
B. Leukocoria
C. Strabismus
D. Secondary glaucoma
6. Which not a clinical presentation of Retinoblastoma
A. Nystagmus
B. Leukocoria
C. Strabismus
D. Growth retardation
7. Which not a differential diagnosis for Retinoblastoma
A. Coat's disease
B. Persistent hyperplastic primary vitreous
C. Endophthalmitis
D. Central retinal vein occlusion
8. Leucocoria is seen in:
A. Cataract
B. Coat's disease
C. Retinopathy of prematurity
D. All
9. If retinoblastoma involves more than half of the retina, the
treatment of choice is:
A. Chemotherapy
B. External beam radiotherapy
C. Enuclaetion
D. Cryotherapy
10. The most preferred combination of chemotherapy for
retinoblastoma is:
A. Methotrexate, etoposide & vinblastin
B. Methotrexate, etoposide & vincristin
C. Carboplatin, etoposide & vinblastin
D. Carboplatin, etoposide & vincritin
Thank You
This post was last modified on 07 April 2022