- Most common primary intraocular malignancy of childhood
- Incidence: 1 in 15,000 live births in the United States
- Girls and boys are affected equally.
- Accounts for about 4% of malignant tumors in children < 15 years of age
- Approximately 95% of affected children are diagnosed before the age of 5.
- The median age of diagnosis is 18–20 months.
- Approximately 40% of cases are heritable.
- In resource-rich countries: > 95%
- In resource-limited/developing countries: < 30%
- Retinoblastoma is caused by a genetic
Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations.
Types of Mutations of the retinoblastoma gene (RB1 or RB) in 98% of cases.
- RB1 is a key negative regulator of the G1/S cell cycle Cell cycle The phases of the cell cycle include interphase (G1, S, and G2) and mitosis (prophase, metaphase, anaphase, and telophase). The cell's progression through these phases is punctuated by checkpoints regulated by cyclins, cyclin-dependent kinases, tumor suppressors, and their antagonists. Cell Cycle transition and is directly or indirectly inactivated in most human malignancies.
- Nonheritable form: (60% of cases)
- Two spontaneous somatic mutations occur in the RB1 gene progenitor cells, leading to the development of retinoblastoma.
- Tends to be unilateral and unifocal
- Presents between the ages of 2 and 5
- Familial or heritable form: (40% of cases)
- The child inherits a non-functional allele of the RB1 gene, which is present in all somatic cells.
- Only 1 more (sporadic) mutation Mutation Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations. Types of Mutations of the 2nd allele in a neuronal progenitor cell is necessary to form a retinoblastoma.
- Tends to be bilateral and/or multifocal
- Presents before the age of 1
- Cardinal signs:
- Less common signs and symptoms:
- Decreased vision
- Ocular inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation
- Vitreous hemorrhage
- Glaucoma Glaucoma Glaucoma is an optic neuropathy characterized by typical visual field defects and optic nerve atrophy seen as optic disc cupping on examination. The acute form of glaucoma is a medical emergency. Glaucoma is often, but not always, caused by increased intraocular pressure (IOP). Glaucoma
- Rarely needed to confirm the diagnosis
- A biopsy is contraindicated because of the risk of tumor seeding.
- Three growth patterns are seen: exophytic (beneath the retina), endophytic (into the vitreous), and diffusely infiltrating (rare, grows within the retina).
- Urgent referral to ophthalmologist
- Ophthalmoscopic examination under anesthesia Anesthesia Anesthesiology is the field of medicine that focuses on interventions that bring a state of anesthesia upon an individual. General anesthesia is characterized by a reversible loss of consciousness along with analgesia, amnesia, and muscle relaxation. Anesthesiology: History and Basic Concepts, with ultrasound imaging
- Magnetic resonance imaging (MRI) of the brain and orbits
- No need for formal staging Staging Cancer is the 2nd leading cause of death in the US after cardiovascular disease. Many malignancies are treatable or curable, but some may recur. Thus, all malignancies must be assigned a grade and stage in order to guide management and determine prognosis. Grading, Staging, and Metastasis studies (i.e., bone marrow Bone marrow Bone marrow, the primary site of hematopoiesis, is found in the cavities of cancellous bones and the medullary canals of long bones. There are 2 types: red marrow (hematopoietic with abundant blood cells) and yellow marrow (predominantly filled with adipocytes). Composition of Bone Marrow examination, lumbar puncture, and/or radionuclide bone scan) → metastases rarely present at time of diagnosis
- Genetic testing is recommended.
Management and Prognosis
Treatment depends on the stage, with multiple “vision-sparing” therapies available:
- Small, uncomplicated extrafoveal tumors: cryotherapy or laser photocoagulation
- More advanced stages: local and systemic chemotherapy, radioactive plaques
- Anatomical or functional impairment by tumor: enucleation
- Metastatic disease:
- Rarely (2%–3%) present at time of diagnosis
- Autologous stem cell transplantation after intensive multimodal therapy
- Lifetime follow-up to detect secondary malignancies is necessary!
- Survival: > 95% in resource-rich countries; < 30% in countries with very limited resources
- Prognosis for vision depends on extent of tumor: 50% of patients reach a final visual acuity of 20/40 or better.
The differential diagnosis includes any condition that can cause leukocoria.
- Persistent fetal vasculature: failure of the embryonic primary vitreous and hyaloid vascular system to involute during gestation. Visual prognosis is poor.
- Retinopathy of prematurity Retinopathy of prematurity Retinopathy of prematurity (ROP) is a condition seen in premature infants of low birth weight that is characterized by progressive and excessive neovascularization. In this condition, the inappropriate proliferation of blood vessels and fibrovascular tissue behind the lens prevents retinal development. Retinopathy of Prematurity (ROP): a potentially blinding eye disorder that primarily affects premature infants. The disorder is caused by neovascularization with abnormal and fragile vessels due to growth factors released by incompletely developed peripheral retinal vessels. The vessels bleed easily and cause scarring. Most cases of ROP are mild.
- Cataract: a congenital or acquired condition in which the lens of the eye becomes progressively opaque, resulting in blurred vision.
- Coats disease: an idiopathic disorder characterized by retinal telangiectasia with breakdown of the blood-retinal barrier. Most commonly affects children. Can cause retinal detachment Retinal detachment Retinal detachment is the separation of the neurosensory retina from the retinal pigmented epithelium and choroid. Rhegmatogenous retinal detachment, the most common type, stems from a break in the retina, allowing fluid to accumulate in the subretinal space. Retinal Detachment and blindness.
- Vitreous hemorrhage (VH): the presence of blood within the vitreous cavity. Three conditions cause most VH cases: ocular trauma, posterior vitreous detachment associated with retinal detachment Retinal detachment Retinal detachment is the separation of the neurosensory retina from the retinal pigmented epithelium and choroid. Rhegmatogenous retinal detachment, the most common type, stems from a break in the retina, allowing fluid to accumulate in the subretinal space. Retinal Detachment, and proliferative diabetic retinopathy.
- Ocular toxocariasis Toxocariasis Toxocariasis is caused by the nematodes Toxocara canis and T. cati. These species frequently infect dogs and cats and are most commonly transmitted to humans via accidental ingestion of eggs through the fecal-oral route. Toxocara are not able to complete their life cycle in humans, but they do migrate to organs (including the liver, lungs, heart, brain, and eyes), where they cause inflammation and tissue damage. Toxocariasis (ocular larva migrans): a rare infection caused by roundworms, Toxocara Toxocara Toxocariasis is caused by the nematodes Toxocara canis and T. cati. These species frequently infect dogs and cats and are most commonly transmitted to humans via accidental ingestion of eggs through the fecal-oral route. Toxocara are not able to complete their life cycle in humans, but they do migrate to organs (including the liver, lungs, heart, brain, and eyes), where they cause inflammation and tissue damage. Toxocariasis canis, and Toxocara Toxocara Toxocariasis is caused by the nematodes Toxocara canis and T. cati. These species frequently infect dogs and cats and are most commonly transmitted to humans via accidental ingestion of eggs through the fecal-oral route. Toxocara are not able to complete their life cycle in humans, but they do migrate to organs (including the liver, lungs, heart, brain, and eyes), where they cause inflammation and tissue damage. Toxocariasis cati. Presents with posterior uveitis Uveitis Uveitis is the inflammation of the uvea, the pigmented middle layer of the eye, which comprises the iris, ciliary body, and choroid. The condition is categorized based on the site of disease; anterior uveitis is the most common. Diseases of the Uvea and is associated with reduced vision, photophobia, floaters, and leukocoria.
- Familial exudative vitreoretinopathy: a group of rare inherited diseases with abnormal retinal angiogenesis causing incomplete vascularization of the peripheral retina. Can lead to secondary neovascularization with progression to blindness.
- Coloboma: a development disorder due to failure of the optic (choroid) fissure to fuse so that a defect may be present anywhere along the inferior portion of the eye, from the optic disc to the iris. A large optic disc and chorioretinal coloboma can cause leukocoria.
- Retinal astrocytic hamartoma: a usually indolent tumor that occurs in roughly half of patients with tuberous sclerosis Tuberous sclerosis Tuberous sclerosis or tuberous sclerosis complex (TSC) is an autosomal dominant disorder with mainly neurocutaneous symptoms. Mutation in the TSC genes causes excessive tumor-like growths in the brain, eyes, heart, kidney, and lungs. Cutaneous manifestations include hypopigmentation (i.e., ash leaf spots, confetti lesions) or excessive growth (i.e., angiofibroma, shagreen patch). Tuberous Sclerosis complex. The condition is also associated with neurofibromatosis.
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