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==Overview==
{{Retinoblastoma}}
{{Retinoblastoma}}
==Overview==
Retinoblastoma is the abnormal overgrowth of the [[retina]], the most inner layer of the eye. [[RB1]] [[gene]] [[mutation]] is the common [[cause]] of this [[malignancy]]. This [[tumor]] affects mostly young children and may result in loss of the [[vision]]. Retinoblastoma was first described in 1809 by Dr. James Wardrop. Then, Dr. Flexner, in 1891, was the first to discover the rosette structure within the [[tumor]]. In 1953, Dr. Kupfer was the first [[ophthalmologist]] who tried a combination of [[chemotherapy]] and [[radiotherapy]] for the treatment of the [[tumor]]. There are several [[classification]] system available for retinoblastoma. As the treatment of the [[tumor]] has evolved, a new [[classification]] system has been introduced. For intraocular [[diseases]] the available grouping systems include the International Intraocular Retinoblastoma [[Classification]] (IIRC), Intraocular [[Classification]] of Retinoblastoma (ICRB) and [[TNM|cTNMH systems]]. For extraocular [[diseases]], the International Retinoblastoma [[Cancer staging|Staging]] System (IRSS) and [[TNM Staging System|cTNMH]] schemes can be used. Retinoblastoma is a [[neoplasm]] which is caused by the inactivation of [[RB1]] [[gene]], a [[tumor suppressor gene]], located on the long arm of the [[chromosome 13]]. [[Mutation]] in both [[alleles]] of the [[RB1]] [[gene]] is necessary for the inactivation of the [[gene]]. This [[disorder]] may occur in the [[familial]] or sporadic form. ([[Rb]]) [[gene]] product limits the [[cell]] progression from the [[G1 phase]] to the [[S phase]] of the [[cell cycle]]. Loss of this active, functional [[protein]] ([[Rb]]) causes [[cell cycle]] [[dysregulation]] and subsequent overgrowth and [[tumor]] formation. Retinoblastoma may be caused by [[mutation]] in both [[allels]] of [[RB1]] [[tumor suppressor gene]] or due to somatic amplification of the ''MYCN'' [[oncogene]]. Retinoblastoma must be differentiated from other [[diseases]] that cause [[leukocoria]]. [[leukocoria]] may occur in several ocular [[conditions]] including [[tumors]], vascular [[disease]], [[inflammatory]] [[disorders]], and also due to [[trauma]]. The [[incidence]] of retinoblastoma in the United States has been reported 1.2 cases per 100,000 child aged 4 years or younger. The median age at [[diagnosis]] of retinoblastoma is 18 months. The average age at [[diagnosis]] of retinoblastoma for children with unilateral [[disease]] and [[bilateral]] [[disease]] is 24 months and 12 months respectively. Retinoblastoma affects males and females equally. There is no [[racial]] predilection to the development of retinoblastoma. [[Risk factors]] associated with the development of retinoblastoma are [[mutation]] in [[RB1 gene]], a positive [[family history]] of retinoblastoma, living in areas with high [[incidence rate]] of the [[disease]], [[HPV]] viral exposure and other environmental factors. Early [[diagnosis]] of retinoblastoma is necessary to obtain the best outcomes for [[vision]] and eye salvage. In 2018, a group of experts in clinical retinoblastoma care and [[ophthalmic]]
Retinoblastoma is the most common [[malignant]] intraocular [[tumor]] in children. Retinoblastoma may be classified into several subgroups based on the International Retinoblastoma Staging System (IRSS). On gross pathology, viable tumor [[cells]] near [[blood vessels]] and zones of necrosis in avascular areas are characteristic findings of retinoblastoma. On [[microscopic]] [[histopathological]] analysis, a small round-cell tumor of neuroepithelial origin, Flexner-Wintersteiner rosettes, and Homer-Wright rosettes are characteristic findings of retinoblastoma. Retinoblastoma can be bilateral or unilateral, spontaneous or [[familial]]. In 30% to 40% of cases, retinoblastoma is accompanied by a germinal mutation in the ''RB1'' [[gene]]. The incidence of retinoblastoma in the United States is approximately 0.43 cases per 100,000 children under 15 years of age. The median age at diagnosis of retinoblastoma is 18 months. The average age at diagnosis of retinoblastoma for children with bilateral and unilateral disease is 12 months and 24 months respectively. Retinoblastoma affects males and females equally. There is no racial predilection to the development of retinoblastoma. Common risk factors in the development of retinoblastoma are advanced paternal age, positive [[family history]], and [[viral]] exposure. The hallmark of retinoblastoma is [[leukocoria]] which is an abnormal appearance of the [[retina]] as viewed through the [[pupil]], also known as amaurotic cat's eye reflex. A positive family history of retinoblastoma may be present. Less common symptoms of retinoblastoma include deterioration of vision, a red and irritated eye, eye [[pain]], [[proptosis]], and [[fever]]. Common physical examination findings of retinoblastoma include [[leukocoria]], [[strabismus]], [[proptosis]], [[anisocoria]], [[orbital cellulitis]], [[hyphema]], [[heterochromia iridis]], poor vision, unilateral [[mydriasis]], [[rubeosis iridis]], vitreous [[hemorrhage]], and findings of chalky white-gray retinal mass on fundoscopic examination. The optimal therapy for retinoblastoma depends on several factors such as tumor size, [[tumor]] location, presence or absence of [[vitreous]] or subretinal seeds, and patient age. The various treatment modalities for retinoblastoma include, [[enucleation]], external beam [[radiation therapy]], radioactive plaques (I-125 [[brachytherapy]]), [[cryotherapy]], [[laser photocoagulation]], [[thermotherapy]], and [[chemotherapy]] (which includes systemic, intra-arterial, and [[intravitreal]]). When the retinoblastoma is too large to be treated by other treatment modalities, surgery may be used. In these situations, [[enucleation]] may help to prevent [[metastasis]].
[[pathology]] and [[genetics]] suggest a risk-stratified schedule for [[ophthalmic]] [[screening]] examinations. Estimated risk of retinoblastoma development is calculated according to the relativity of individuals to the family member with retinoblastoma. If left untreated, retinoblastoma may progress to develop seeding in the [[eye]], leading to [[retinal detachment]], [[necrosis]] and [[invasion]] of the [[orbit]], [[optic nerve]] [[invasion]], and [[central nervous system]] invasion. The majority of untreated patients die of intracranial extension and disseminated [[disease]] within one year. Spontaneous regression of the [[tumor]] is a rare occurrence but may occur in a small number of cases. Common [[complications]] of retinoblastoma include [[metastasis]], [[tumor]] recurrence, trilateral retinoblastoma, and subsequent [[neoplasms]]. [[Prognosis]] is generally good, and the [[survival rate]] of [[patients]] with retinoblastoma with treatment is approximately 95% in the United States. [[Ultrasound imaging]] is the [[Gold standard (test)|gold standard test]] for the [[diagnosis]] of retinoblastoma. [[Magnetic resonance imaging|MRI]] can also be helpful in the [[diagnosis]] making. A common method of retinoblastoma [[classification]] is critical to plan treatment, evaluate [[prognosis]] and compare outcomes. Available grouping systems include the International Intraocular [[Retinoblastoma]] [[Classification]] (IIRC), Intraocular [[Classification]] of Retinoblastoma (ICRB) and [[TNM|cTNMH systems]] [[diseases]]. The hallmark of retinoblastoma is [[leukocoria]] which is an abnormal appearance of the [[retina]] as viewed through the [[pupil]], also known as amaurotic cat's eye reflex. Other common [[symptoms]] include [[strabismus]] and [[proptosis]]. The [[clinical]] presentation depends on the stage of the [[disease]]. Patients with retinoblastoma usually appear normal. [[Physical examination]] of patients is usually remarkable for [[leukocoria]], [[strabismus]], and [[proptosis]], particularly in advanced cases. Other findings in [[physical examination]] of retinoblastoma include [[anisocoria]], [[orbital cellulitis]], [[hyphema]], [[heterochromia iridis]], poor [[visual acuity]], unilateral [[mydriasis]], [[rubeosis iridis]], [[vitreous]] [[hemorrhage]], and findings of intrinsic [[calcification]] on fundoscopic examination. There are no [[diagnostic]] [[laboratory]] findings associated with retinoblastoma. There are no [[x-ray]] findings associated with retinoblastoma. On [[ultrasound imaging]], retinoblastoma is characterized by [[echogenic]] [[soft-tissue]] [[Mass|masses]] with variable shadowing due to [[Calcification|calcifications]] and heterogeneity due to [[necrosis]] and/or [[hemorrhage]]. [[CT scan]] has been the standard [[Imaging studies|imaging study]] of retinoblastoma. Retinoblastoma usually appears as an intra-[[ocular]] [[mass]] with [[calcification]] (in 80% of the cases). On [[head]] and [[neck]] [[MRI]], retinoblastoma is characterized by hyperintense [[mass]] on T1-weighted [[MRI]] and hypointense [[mass]] on T2-weighted [[MRI]]. [[Optical coherence tomography]] may be helpful in the [[diagnosis]] of Retinoblastoma. Other [[Diagnosis|diagnostic]] studies for retinoblastoma include [[fluorescein angiography]] and [[electroretinogram]]. The optimal [[therapy]] for retinoblastoma depends on the stage at [[diagnosis]]. [[Systemic]] [[chemotherapy]] via [[carboplatin]], [[etoposide]], and [[vincristine]] (CEV) is the most common regimen used to treat retinoblastoma. There are different modalities of treatment available for retinoblastoma. The feasibility of each strategy depends on the [[Cancer staging|stage]] of retinoblastoma at the time of [[diagnosis]]. There are no established measures for the [[Prevention (medical)|primary prevention]] of retinoblastoma. There are no established measures for the [[Prevention (medical)|secondary prevention]] of retinoblastoma.  
==Historic Perspective==
==Historic Perspective==
Retinoblastoma was first described in 1809 by James Wardrop.
Retinoblastoma was first described in 1809 by Dr. James Wardrop. Then, Dr. Flexner, in 1891, was the first to discover the rosette structure within the [[tumor]]. In 1953, Dr. Kupfer was the first [[ophthalmologist]] who tried a combination of [[chemotherapy]] and [[radiotherapy]] for the treatment of the [[tumor]].
==Classification==
==Classification==
Retinoblastoma may be classified into several subgroups based on the International Retinoblastoma Staging System (IRSS).
There are several [[classification]] system available for retinoblastoma. As the treatment of the [[tumor]] has evolved, a new [[classification]] system has been introduced. For intraocular [[diseases]] the available grouping systems include the International Intraocular Retinoblastoma [[Classification]] (IIRC), Intraocular [[Classification]] of Retinoblastoma (ICRB) and [[TNM|cTNMH systems]]. For extraocular [[diseases]], the International Retinoblastoma [[Cancer staging|Staging]] System (IRSS) and [[TNM Staging System|cTNMH]] schemes can be used.
==Pathophysiology==
==Pathophysiology==
On gross pathology, viable [[tumor]] [[cells]] near [[blood vessels]] and zones of [[necrosis]] in [[avascular]] areas are characteristic findings of retinoblastoma. On microscopic [[histopathological]] analysis, a small round-cell tumor of neuroepithelial origin, Flexner-Wintersteiner rosettes, and Homer-Wright rosettes are characteristic findings of retinoblastoma. Retinoblastoma can be bilateral or unilateral, spontaneous or familial. In 30% to 40% of cases retinoblastoma is accompanied by a germinal [[mutation]] in the ''RB1'' [[gene]].
Retinoblastoma is a [[neoplasm]] which is caused by the inactivation of [[RB1]] [[gene]], a [[tumor suppressor gene]], located on the long arm of the [[chromosome 13]]. [[Mutation]] in both [[alleles]] of the [[RB1]] [[gene]] is necessary for the inactivation of the [[gene]]. This [[disorder]] may occur in the [[familial]] or sporadic form. ([[Rb]]) [[gene]] product limits the [[cell]] progression from the [[G1 phase]] to the [[S phase]] of the [[cell cycle]]. Loss of this active, functional [[protein]] ([[Rb]]) causes [[cell cycle]] [[dysregulation]] and subsequent overgrowth and [[tumor]] formation.
==Causes==
==Causes==
Retinoblastoma is caused by a [[mutation]] in the ''RB1'' gene.
Retinoblastoma may be caused by [[mutation]] in both [[allels]] of [[RB1]] [[tumor suppressor gene]] or due to somatic amplification of the ''MYCN'' [[oncogene]].
==Differential Diagnosis==
==Differentiating Retinoblastoma from Other Diseases==
Retinoblastoma must be differentiated from other diseases that cause [[leukocoria]] such as [[congenital]] [[cataract]], persistent fetal [[vasculature]], [[Coats disease]], coloboma of [[choroid]] or [[optic disc]], [[toxocariasis]], [[astrocytic]] [[hamartoma]], [[retinopathy of prematurity]], [[vitreous]] [[hemorrhage]], [[uveitis]], [[retinal dysplasia]], and [[medulloepithelioma]].
Retinoblastoma must be differentiated from other [[diseases]] that cause [[leukocoria]]. [[leukocoria]] may occur in several ocular [[conditions]] including [[tumors]], vascular [[disease]], [[inflammatory]] [[disorders]], and also due to [[trauma]].
==Epidemiology and Demographics==
==Epidemiology and Demographics==
The incidence of retinoblastoma in the United States is approximately .43 cases per 1000,000 children under 15 years of age. The median age at diagnosis of retinoblastoma is 18 months. The average age at diagnosis of retinoblastoma for children with unilateral disease and bilateral disease is 24 months and 12 months respectively. Retinoblastoma affects males and females equally. There is no racial predilection to the development of retinoblastoma.
The [[incidence]] of retinoblastoma in the United States has been reported 1.2 cases per 100,000 child aged 4 years or younger. The median age at [[diagnosis]] of retinoblastoma is 18 months. The average age at [[diagnosis]] of retinoblastoma for children with unilateral [[disease]] and [[bilateral]] [[disease]] is 24 months and 12 months respectively. Retinoblastoma affects males and females equally. There is no [[racial]] predilection to the development of retinoblastoma.  
==Risk factors==
==Risk factors==
Common risk factors in the development of retinoblastoma are advanced paternal age, positive [[family history]], and [[viral]] exposure.
[[Risk factors]] associated with the development of retinoblastoma are [[mutation]] in [[RB1 gene]], a positive [[family history]] of retinoblastoma, living in areas with high [[incidence rate]] of the [[disease]], [[HPV]] viral exposure and other [[Environmental factor|environmental factors]].
==Screening==
==Screening==
According to the United States Preventive Services Task Force, screening for retinoblastoma is not recommended in the general population. However, children with an increased risk of retinoblastoma such as those with a known 13q deletion or [[family history]] should be evaluated by an [[ophthalmologist]] shortly after birth. Dilated fundus examinations are recommended in siblings and offspring of patients with retinoblastoma.
Early [[diagnosis]] of retinoblastoma is necessary to obtain the best outcomes for [[vision]] and eye salvage. In 2018, a group of experts in clinical retinoblastoma care and [[ophthalmic]]
[[pathology]] and [[genetics]] suggest a risk-stratified schedule for [[ophthalmic]] [[screening]] examinations. Estimated risk of retinoblastoma development is calculated according to the relativity of individuals to the family member with retinoblastoma.
==Natural history, Complications, and Prognosis==
If left untreated, retinoblastoma may progress to develop seeding in the [[eye]], leading to [[retinal detachment]], [[necrosis]] and [[invasion]] of the [[orbit]], [[optic nerve]] [[invasion]], and [[central nervous system]] invasion. The majority of untreated [[Patient|patients]] die of [[Cranium|intracranial]] extension and disseminated [[disease]] within one year. Spontaneous regression of the [[tumor]] is a rare occurrence but may occur in a small number of cases. Common [[complications]] of retinoblastoma include [[metastasis]], [[tumor]] recurrence, trilateral retinoblastoma, and subsequent [[neoplasms]]. [[Prognosis]] is generally good, and the [[survival rate]] of [[patients]] with retinoblastoma with treatment is approximately 95% in the United States.
==Daignosis==
===Diagnostic Study of Choice===
[[Ultrasound imaging]] is the [[Gold standard (test)|gold standard test]] for the [[diagnosis]] of retinoblastoma. [[Magnetic resonance imaging|MRI]] can also be helpful in the [[diagnosis]] making. A common method of retinoblastoma [[classification]] is critical to plan treatment, evaluate [[prognosis]] and compare outcomes. Available grouping systems include the International Intraocular [[Retinoblastoma]] [[Classification]] (IIRC), Intraocular [[Classification]] of Retinoblastoma (ICRB) and [[TNM|cTNMH systems]] [[diseases]].


==Natural history,Complications and Prognosis==
===History and Symptoms===
If left untreated, retinoblastoma may progress to develop seeding in the eye, leading to [[retinal detachment]], [[necrosis]] and invasion of the orbit, [[optic nerve]] invasion, and [[central nervous system]] invasion. The majority of untreated patients die of intracranial extension and disseminated disease within one year. Spontaneous regression of the tumor is a rare occurrence but may occur in a small number of cases. Common complications of retinoblastoma include [[metastasis]], [[tumor]] recurrence, trilateral [[retinoblastoma]], and subsequent neoplasms. Prognosis is generally good, and the survival rate of patients with retinoblastoma with treatment is approximately 95% in the United States.
The hallmark of retinoblastoma is [[leukocoria]] which is an abnormal appearance of the [[retina]] as viewed through the [[pupil]], also known as amaurotic cat's eye reflex. Other common [[symptoms]] include [[strabismus]] and [[proptosis]]. The [[clinical]] presentation depends on the stage of the [[disease]].
==History and Symptoms==
===Physical Examination===
The hallmark of retinoblastoma is [[leukocoria]] which is an abnormal appearance of the [[retina]] as viewed through the [[pupil]], also known as amaurotic cat's eye reflex. A positive [[family history]] of retinoblastoma may be present. Less common symptoms of retinoblastoma include deterioration of vision, a red and irritated eye, [[eye pain]], [[proptosis]], and fever.
[[Patient|Patients]] with retinoblastoma usually appear normal. [[Physical examination]] of [[Patient|patients]] is usually remarkable for [[leukocoria]], [[strabismus]], and [[proptosis]], particularly in advanced cases. Other findings on [[physical examination]] of retinoblastoma include [[anisocoria]], [[orbital cellulitis]], [[hyphema]], [[heterochromia iridis]], poor [[visual acuity]], unilateral [[mydriasis]], [[rubeosis iridis]], [[vitreous]] [[hemorrhage]], and findings of intrinsic [[calcification]] on [[Fundoscopy|fundoscopic examination]].
==Physical Examination==
Common physical examination findings of retinoblastoma include [[leukocoria]], [[strabismus]], [[proptosis]], [[anisocoria]], [[orbital cellulitis]], [[hyphema]], [[heterochromia iridis]], poor vision, unilateral [[mydriasis]], [[rubeosis iridis]], vitreous [[hemorrhage]], and findings of chalky white-gray retinal mass on fundoscopic examination.
==Laboratory Tests==
There are no diagnostic lab findings associated with retinoblastoma.
==Chest X Ray==
There are no chest x-ray findings associated with retinoblastoma.
==CT scan==
[[Head]] and [[neck]] [[CT scan]] may be diagnostic of retinoblastoma. Findings on CT scan suggestive of retinoblastoma include retrolental mass that is usually calcified and a dense vitreous due to [[hemorrhage]].
==MRI scan==
On [[head]] and [[neck]] [[MRI]], retinoblastoma is characterized by isointense to hypointense mass on T1-weighted MRI and hyperintense mass on T2-weighted MRI.


==Ultrasound==
===Laboratory Findings===
On ultrasound, retinoblastoma is characterized by echogenic soft-tissue masses with variable shadowing due to calcifications and heterogeneity due to [[necrosis]] and/or [[hemorrhage]].
There are no [[diagnostic]] [[laboratory]] findings associated with retinoblastoma.
==Other Imaging Studies==
===Electrocardiogram===
Other imaging studies for retinoblastoma include wide-field [[fundus]] photography and spectral domain optical coherence tomography.
There are no [[ECG]] findings associated with retinoblastoma.
==Other Diagnostic Studies==
===X Ray===
Other diagnostic studies for retinoblastoma include [[fluorescein angiography]], [[bone marrow aspiration]], [[lumbar puncture]], [[bone scan]], and [[genetic testing]].
There are no [[x-ray]] findings associated with retinoblastoma.
==Medical therapy==
===Echocardiography and Ultrasound===
The optimal therapy for retinoblastoma depends on several factors such as [[tumor]] size, tumor location, presence or absence of [[vitreous]] or subretinal seeds, and patient age. The various treatment modalities for retinoblastoma include [[enucleation]], external beam [[radiation therapy]], radioactive plaques (I-125 [[brachytherapy]]), [[cryotherapy]], [[laser photocoagulation]], [[thermotherapy]], and [[chemotherapy]] (which includes systemic, intra-arterial, and [[intravitreal]]).
On [[ultrasound imaging]], retinoblastoma is characterized by echogenic [[Soft tissue|soft-tissue]] [[Mass|masses]] with variable shadowing due to [[calcification]] and [[heterogeneity]] due to [[necrosis]] and/or [[hemorrhage]].
==Surgical therapy==
===CT scan===
The feasibility of surgery depends on the tumor size, tumor location, and presence or absence of vitreous or subretinal seeds at diagnosis. When the retinoblastoma is too large to be treated by other treatment modalities, [[surgery]] may be used. In these situations, enucleation may help to prevent [[metastasis]].
[[CT scan]] has been the standard [[Imaging studies|imaging study]] of retinoblastoma. Retinoblastoma usually appears as an intra-[[ocular]] [[mass]] with [[calcification]] (in 80% of the cases).
==Primary Prevention==
===MRI scan===
There are no primary preventive measures available for retinoblastoma.
[[Magnetic resonance imaging|MRI]] findings of retinoblastoma include hyperintense [[mass]] on T1-weighted [[MRI]] and hypointense [[mass]] on T2-weighted [[MRI]].
==Secondary Prevention==
===Other Imaging Findings===
Secondary prevention strategies following retinoblastoma include cessation of smoking, reduction in sun exposure, and reduction in exposure to [[ionizing radiation]].
[[Optical coherence tomography]] may be helpful in the [[diagnosis]] of Retinoblastoma.
===Other Diagnostic Studies===
Other [[Diagnosis|diagnostic]] studies for retinoblastoma include [[fluorescein angiography]] and [[electroretinogram]].
==Treatment==
===Medical therapy===
The optimal [[therapy]] for retinoblastoma depends on the stage at [[diagnosis]]. [[Systemic]] [[chemotherapy]] via [[carboplatin]], [[etoposide]], and [[vincristine]] (CEV) is the most common regimen used to treat retinoblastoma.
===Surgery===
There are different modalities of treatment available for retinoblastoma. The feasibility of each strategy depends on the [[Cancer staging|stage]] of retinoblastoma at the time of [[diagnosis]].
===Primary Prevention===
There are no established measures for the [[Prevention (medical)|primary prevention]] of retinoblastoma.
===Secondary Prevention===
There are no established measures for the [[Prevention (medical)|secondary prevention]] of retinoblastoma.
==References==
==References==
{{reflist|2}}
{{reflist|2}}
[[Category:Medicine]]
[[Category:Medicine]]
[[Category:Oncology]]
[[Category:Oncology]]
[[Category:Up-To-Date]]​
[[Category:Up-To-Date]]
[[Category:Primary care]]
[[Category:Surgery]]
[[Category:Surgery]]

Latest revision as of 23:59, 29 July 2020

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sahar Memar Montazerin, M.D.[2] Simrat Sarai, M.D. [3]

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Retinoblastoma is the abnormal overgrowth of the retina, the most inner layer of the eye. RB1 gene mutation is the common cause of this malignancy. This tumor affects mostly young children and may result in loss of the vision. Retinoblastoma was first described in 1809 by Dr. James Wardrop. Then, Dr. Flexner, in 1891, was the first to discover the rosette structure within the tumor. In 1953, Dr. Kupfer was the first ophthalmologist who tried a combination of chemotherapy and radiotherapy for the treatment of the tumor. There are several classification system available for retinoblastoma. As the treatment of the tumor has evolved, a new classification system has been introduced. For intraocular diseases the available grouping systems include the International Intraocular Retinoblastoma Classification (IIRC), Intraocular Classification of Retinoblastoma (ICRB) and cTNMH systems. For extraocular diseases, the International Retinoblastoma Staging System (IRSS) and cTNMH schemes can be used. Retinoblastoma is a neoplasm which is caused by the inactivation of RB1 gene, a tumor suppressor gene, located on the long arm of the chromosome 13. Mutation in both alleles of the RB1 gene is necessary for the inactivation of the gene. This disorder may occur in the familial or sporadic form. (Rb) gene product limits the cell progression from the G1 phase to the S phase of the cell cycle. Loss of this active, functional protein (Rb) causes cell cycle dysregulation and subsequent overgrowth and tumor formation. Retinoblastoma may be caused by mutation in both allels of RB1 tumor suppressor gene or due to somatic amplification of the MYCN oncogene. Retinoblastoma must be differentiated from other diseases that cause leukocoria. leukocoria may occur in several ocular conditions including tumors, vascular disease, inflammatory disorders, and also due to trauma. The incidence of retinoblastoma in the United States has been reported 1.2 cases per 100,000 child aged 4 years or younger. The median age at diagnosis of retinoblastoma is 18 months. The average age at diagnosis of retinoblastoma for children with unilateral disease and bilateral disease is 24 months and 12 months respectively. Retinoblastoma affects males and females equally. There is no racial predilection to the development of retinoblastoma. Risk factors associated with the development of retinoblastoma are mutation in RB1 gene, a positive family history of retinoblastoma, living in areas with high incidence rate of the disease, HPV viral exposure and other environmental factors. Early diagnosis of retinoblastoma is necessary to obtain the best outcomes for vision and eye salvage. In 2018, a group of experts in clinical retinoblastoma care and ophthalmic pathology and genetics suggest a risk-stratified schedule for ophthalmic screening examinations. Estimated risk of retinoblastoma development is calculated according to the relativity of individuals to the family member with retinoblastoma. If left untreated, retinoblastoma may progress to develop seeding in the eye, leading to retinal detachment, necrosis and invasion of the orbit, optic nerve invasion, and central nervous system invasion. The majority of untreated patients die of intracranial extension and disseminated disease within one year. Spontaneous regression of the tumor is a rare occurrence but may occur in a small number of cases. Common complications of retinoblastoma include metastasis, tumor recurrence, trilateral retinoblastoma, and subsequent neoplasms. Prognosis is generally good, and the survival rate of patients with retinoblastoma with treatment is approximately 95% in the United States. Ultrasound imaging is the gold standard test for the diagnosis of retinoblastoma. MRI can also be helpful in the diagnosis making. A common method of retinoblastoma classification is critical to plan treatment, evaluate prognosis and compare outcomes. Available grouping systems include the International Intraocular Retinoblastoma Classification (IIRC), Intraocular Classification of Retinoblastoma (ICRB) and cTNMH systems diseases. The hallmark of retinoblastoma is leukocoria which is an abnormal appearance of the retina as viewed through the pupil, also known as amaurotic cat's eye reflex. Other common symptoms include strabismus and proptosis. The clinical presentation depends on the stage of the disease. Patients with retinoblastoma usually appear normal. Physical examination of patients is usually remarkable for leukocoria, strabismus, and proptosis, particularly in advanced cases. Other findings in physical examination of retinoblastoma include anisocoria, orbital cellulitis, hyphema, heterochromia iridis, poor visual acuity, unilateral mydriasis, rubeosis iridis, vitreous hemorrhage, and findings of intrinsic calcification on fundoscopic examination. There are no diagnostic laboratory findings associated with retinoblastoma. There are no x-ray findings associated with retinoblastoma. On ultrasound imaging, retinoblastoma is characterized by echogenic soft-tissue masses with variable shadowing due to calcifications and heterogeneity due to necrosis and/or hemorrhage. CT scan has been the standard imaging study of retinoblastoma. Retinoblastoma usually appears as an intra-ocular mass with calcification (in 80% of the cases). On head and neck MRI, retinoblastoma is characterized by hyperintense mass on T1-weighted MRI and hypointense mass on T2-weighted MRI. Optical coherence tomography may be helpful in the diagnosis of Retinoblastoma. Other diagnostic studies for retinoblastoma include fluorescein angiography and electroretinogram. The optimal therapy for retinoblastoma depends on the stage at diagnosis. Systemic chemotherapy via carboplatin, etoposide, and vincristine (CEV) is the most common regimen used to treat retinoblastoma. There are different modalities of treatment available for retinoblastoma. The feasibility of each strategy depends on the stage of retinoblastoma at the time of diagnosis. There are no established measures for the primary prevention of retinoblastoma. There are no established measures for the secondary prevention of retinoblastoma.

Historic Perspective

Retinoblastoma was first described in 1809 by Dr. James Wardrop. Then, Dr. Flexner, in 1891, was the first to discover the rosette structure within the tumor. In 1953, Dr. Kupfer was the first ophthalmologist who tried a combination of chemotherapy and radiotherapy for the treatment of the tumor.

Classification

There are several classification system available for retinoblastoma. As the treatment of the tumor has evolved, a new classification system has been introduced. For intraocular diseases the available grouping systems include the International Intraocular Retinoblastoma Classification (IIRC), Intraocular Classification of Retinoblastoma (ICRB) and cTNMH systems. For extraocular diseases, the International Retinoblastoma Staging System (IRSS) and cTNMH schemes can be used.

Pathophysiology

Retinoblastoma is a neoplasm which is caused by the inactivation of RB1 gene, a tumor suppressor gene, located on the long arm of the chromosome 13. Mutation in both alleles of the RB1 gene is necessary for the inactivation of the gene. This disorder may occur in the familial or sporadic form. (Rb) gene product limits the cell progression from the G1 phase to the S phase of the cell cycle. Loss of this active, functional protein (Rb) causes cell cycle dysregulation and subsequent overgrowth and tumor formation.

Causes

Retinoblastoma may be caused by mutation in both allels of RB1 tumor suppressor gene or due to somatic amplification of the MYCN oncogene.

Differentiating Retinoblastoma from Other Diseases

Retinoblastoma must be differentiated from other diseases that cause leukocoria. leukocoria may occur in several ocular conditions including tumors, vascular disease, inflammatory disorders, and also due to trauma.

Epidemiology and Demographics

The incidence of retinoblastoma in the United States has been reported 1.2 cases per 100,000 child aged 4 years or younger. The median age at diagnosis of retinoblastoma is 18 months. The average age at diagnosis of retinoblastoma for children with unilateral disease and bilateral disease is 24 months and 12 months respectively. Retinoblastoma affects males and females equally. There is no racial predilection to the development of retinoblastoma.

Risk factors

Risk factors associated with the development of retinoblastoma are mutation in RB1 gene, a positive family history of retinoblastoma, living in areas with high incidence rate of the disease, HPV viral exposure and other environmental factors.

Screening

Early diagnosis of retinoblastoma is necessary to obtain the best outcomes for vision and eye salvage. In 2018, a group of experts in clinical retinoblastoma care and ophthalmic pathology and genetics suggest a risk-stratified schedule for ophthalmic screening examinations. Estimated risk of retinoblastoma development is calculated according to the relativity of individuals to the family member with retinoblastoma.

Natural history, Complications, and Prognosis

If left untreated, retinoblastoma may progress to develop seeding in the eye, leading to retinal detachment, necrosis and invasion of the orbit, optic nerve invasion, and central nervous system invasion. The majority of untreated patients die of intracranial extension and disseminated disease within one year. Spontaneous regression of the tumor is a rare occurrence but may occur in a small number of cases. Common complications of retinoblastoma include metastasis, tumor recurrence, trilateral retinoblastoma, and subsequent neoplasms. Prognosis is generally good, and the survival rate of patients with retinoblastoma with treatment is approximately 95% in the United States.

Daignosis

Diagnostic Study of Choice

Ultrasound imaging is the gold standard test for the diagnosis of retinoblastoma. MRI can also be helpful in the diagnosis making. A common method of retinoblastoma classification is critical to plan treatment, evaluate prognosis and compare outcomes. Available grouping systems include the International Intraocular Retinoblastoma Classification (IIRC), Intraocular Classification of Retinoblastoma (ICRB) and cTNMH systems diseases.

History and Symptoms

The hallmark of retinoblastoma is leukocoria which is an abnormal appearance of the retina as viewed through the pupil, also known as amaurotic cat's eye reflex. Other common symptoms include strabismus and proptosis. The clinical presentation depends on the stage of the disease.

Physical Examination

Patients with retinoblastoma usually appear normal. Physical examination of patients is usually remarkable for leukocoria, strabismus, and proptosis, particularly in advanced cases. Other findings on physical examination of retinoblastoma include anisocoria, orbital cellulitis, hyphema, heterochromia iridis, poor visual acuity, unilateral mydriasis, rubeosis iridis, vitreous hemorrhage, and findings of intrinsic calcification on fundoscopic examination.

Laboratory Findings

There are no diagnostic laboratory findings associated with retinoblastoma.

Electrocardiogram

There are no ECG findings associated with retinoblastoma.

X Ray

There are no x-ray findings associated with retinoblastoma.

Echocardiography and Ultrasound

On ultrasound imaging, retinoblastoma is characterized by echogenic soft-tissue masses with variable shadowing due to calcification and heterogeneity due to necrosis and/or hemorrhage.

CT scan

CT scan has been the standard imaging study of retinoblastoma. Retinoblastoma usually appears as an intra-ocular mass with calcification (in 80% of the cases).

MRI scan

MRI findings of retinoblastoma include hyperintense mass on T1-weighted MRI and hypointense mass on T2-weighted MRI.

Other Imaging Findings

Optical coherence tomography may be helpful in the diagnosis of Retinoblastoma.

Other Diagnostic Studies

Other diagnostic studies for retinoblastoma include fluorescein angiography and electroretinogram.

Treatment

Medical therapy

The optimal therapy for retinoblastoma depends on the stage at diagnosis. Systemic chemotherapy via carboplatin, etoposide, and vincristine (CEV) is the most common regimen used to treat retinoblastoma.

Surgery

There are different modalities of treatment available for retinoblastoma. The feasibility of each strategy depends on the stage of retinoblastoma at the time of diagnosis.

Primary Prevention

There are no established measures for the primary prevention of retinoblastoma.

Secondary Prevention

There are no established measures for the secondary prevention of retinoblastoma.

References