Retinoblastoma

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Retinoblastoma (Rb) is a rare form of cancer that develops rapidly from immature retinal cells, eye tissue that detects light. It is the primary malignant intraocular cancer most common in children, and is almost exclusively found in children.

Although most children survive this cancer, they may lose sight of the affected eye or should be removed.

Almost half of children with retinoblastoma have a hereditary genetic defect associated with retinoblastoma. In other cases, this is due to a congenital mutation in the 13th chromosome gene (protein retinoblastoma).

Video Retinoblastoma

Classification

There are two forms of disease, inherited forms and non-inherited forms (all cancers are considered genetic in the genome mutations necessary for their development, but this does not mean that they are inherited, or transmitted to the offspring). Approximately 55% of children with retinoblastoma have a form that is not inherited. If there is no family history of disease, the disease is labeled "sporadic", but this does not necessarily indicate that it is an inherited form. Bilateral retinoblastoma is generally inherited, while unilateral retinoblastoma is generally not inherited.

In about two-thirds of cases, only one eye is affected (unilateral retinoblastoma); in the other third, the tumor develops in both eyes (bilateral retinoblastoma). The number and size of tumors in each eye may vary. In certain cases, the pineal or suprasellar glands or paracellar regions (or in very rare cases, other midline intracranial sites) are also affected (trilateral retinoblastoma). The position, size and quantity of the tumor are considered when choosing the type of treatment for the disease.

Maps Retinoblastoma

Signs and symptoms

The most common and obvious sign of retinoblastoma is the abnormal retinal appearance seen through the pupil, the medical term for leukocoria, also known as the amaurotic cat's eye reflex. Other signs and symptoms include vision impairment, red eyes and irritation with glaucoma, and delayed growth or delayed development. Some children with retinoblastoma may develop a squint, commonly referred to as a "squint eye" or "cross-eyed eye" (strabismus). Retinoblastoma arises with advanced disease in developing countries and eye enlargement is a common finding.

Depending on the position of the tumor, they may be seen during a simple eye exam using the ophthalmoscope to see through the pupil. Positive diagnosis is usually done only under examination under anesthesia (EUA). Reflection of white eyes is not always a positive indication of retinoblastoma and can be caused by poorly reflected light or by other conditions such as Coats disease.

The presence of red-eye photographic errors in just one eye and not in the eyes of another may be a sign of retinoblastoma. Clearer signs are "white eye" or "cat's eye" (leukocoria).

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Cause

Mutation of genes, found on chromosomes, can affect the way cells grow and thrive in the body. Changes in RB1 or MYCN can cause retinoblastoma.

RB1 ​​â € <â € <

In children with genetically inherited forms of retinoblastoma there are mutations in the RB1 gene on chromosome 13. RB1 is the first cloned tumor suppressor gene. Although RB1 interacts with more than 100 protein cells, the negative regulator effect on the cell cycle essentially arises from the binding and inactivation of the transcription factor E2F, thus suppressing the transcription of genes necessary for phase S.

The damaged RB1 gene may be inherited from one of the parent; in some children, however, mutations occur in the early stages of fetal development. The expression of the autosomal dominant RB1 allele with 90% penetration.

The inherited form of retinoblastoma is more likely to be bilateral. In addition, uni or bilateral retinoblastoma may be associated with pineoblastoma and other malignant superficially malignant neuroectodermal tumors (PNET) with poor results; retinoblastoma together with PNET is known as trilateral retinoblastoma. A recent meta-analysis shows that the survival of trilateral retinoblastoma has increased substantially over the last few decades.

The development of retinoblastoma can be explained by a two-hit model. According to the two-hit model, both alleles need to be affected, so two events are required for the retinal or cell cell to develop into a tumor. The first mutated event can be inherited (germline or constitutional) which will then be present in all cells in the body. The second "hit" results in the loss of the remaining normal allele (gen) and occurs within a particular retinal cell. In the form of sporadic retinoblastoma and unwarranted, both mutation events occur in a single retinal cell after fertilization (somatic events); Sporadic retinoblastoma tends to be unilateral.

Several methods have been developed to detect RB1 gene mutations. Attempts to link the gene mutations to the stage of presentation have not shown convincing correlation evidence.

MYCN

Somatic amplification of MYCN oncogenes is responsible for some cases of unilateral, early, aggressive, unilateral retinoblastoma. Although MYCN amplification accounts for only 1.4% of cases of retinoblastoma, the researchers identified it in 18% of infants diagnosed at less than 6 months of age. The mean age at diagnosis for MYCN retinoblastoma was 4.5 months, compared with 24 months for those with non-familial unilateral disease with two RB1 gene mutations.

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Diagnosis

Screening for retinoblastoma should be a part of "good baby" screening for newborns during the first three months of life, to include:

• Red reflex: checks normal reddish orange reflections from the retina of the eye with an ophthalmoscope or retinoscope of about 30 cm/1 feet, usually in a dimly lit or dark room.
• Corneal light reflex/Hirschberg test: checks the symmetrical reflection of the light beam in the same spot on each eye as light shines into each cornea, to help determine whether the eye is crossed.
• Eye examination: check any structural abnormality.
• Bryan Shaw helps develop smart phone applications that can detect leukocoria in photos.

Differential diagnosis

1. Vitreous persistent hyperplastic primer (PHPV): congenital anomalous eye development resulting from embryological failure, primary vitreous vascularization and hyaloid to retreat, where the eyes are shorter, develop cataracts, and may present with bleeding of the pupil. dd>

2. Coats Disease: Unilateral disease characterized by abnormal development of blood vessels behind the retina, which causes abnormal blood vessels in the retina and retinal release to mimic retinoblastoma.

3. Toxocara canis: eye infectious disease associated with exposure to infected puppies, leading to retinal lesions leading to retinal release.

4. Retinopathy of prematurity (ROP): Associated with low birth weight infants who receive supplemental oxygen in the immediate aftermath period, this involves damage to the retinal tissue and may cause retinal detachment.

If an eye exam is abnormal, further testing may include imaging studies, such as computerized tomography (CT), magnetic resonance imaging (MRI), and ultrasound. CT and MRI may help determine structural abnormalities and reveal calcium deposits. Ultrasound can help determine the height and thickness of the tumor. Bone marrow examination or lumbar puncture can also be performed to determine metastasis to bone or brain.

Morphology

The gross and microscopic appearance of retinoblastoma is identical in the hereditary and sporadic types. The tumor cells can be found macro and can be found near the blood vessels, while the necrotic zone is found in a relatively avascular area. Microscopically, both distinguished and distinguished elements can be present. The undifferentiated elements appear as a collection of small round cells with a hyperchromatic nucleus; Differentiated elements include the Rosemary Flexner-Wintersteiner, the Homer Wright rosette, and the fleurettes of photoreceptor differentiation.

Genetic testing

Identifying gene mutations that cause child retinoblastoma can be important in the clinical care of affected individuals and in the care of (future) siblings and offspring. It can run in families.

1. Persons affected by bilateral and 13-15% of unilaterally affected individuals are expected to show a RB1 mutation in the blood. By identifying mutations RB1 ​​â € <â € < on affected individuals, relatives (in the future), children and other relatives can be tested for mutations; if they do not carry the mutation, the child's relatives are not at risk of retinoblastoma so there is no need to undergo the trauma and examination fees under anesthesia. For 85% of unilaterally affected patients found not to carry any of their eye tumors, a RB1 mutation in the blood, both molecular testing and sibling clinical monitoring are required.
2. If the mutations of RB1 ​​â € <â € < of the affected individual are identified, the amniotic cells in pregnancy at risk can be tested for family mutations; any fetus carrying a mutation can be delivered early, allowing early treatment of any eye tumor, leading to better visual outcomes.
3. For the case of unilateral retinoblastoma where no eye tumor is available for testing, if no detectable RB1 mutation is detected in the blood after high sensitivity molecular testing (ie & gt; 93% sensitivity of mutation detection RB1), the risk of germline mutation RB1 ​​ is reduced to less than 1%, the rate at which only clinical examination (and not anesthetic examination) affected and future offspring (National Retinoblastoma Strategy, Canada Guidelines for Treatment).

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Treatment

The priority of retinoblastoma treatment is to maintain a child's life, then maintain vision, and then minimize complications or side effects of treatment. Appropriate treatment will depend on the individual case and will be decided by the ophthalmologist in a discussion with pediatric oncologists. Children with eye involvement in diagnosis usually require multimodality therapy (chemotherapy, local therapy)

The various modalities of treatment for retinoblastoma include:

• Eye surgery - Most patients with unilateral disease present with advanced intraocular disease and therefore are usually enucleated, resulting in a 95% cure rate. In bilateral R b, enucleation is usually reserved for the eyes that have failed in all known effective therapies or without useful vision.
External radiotherapy (EBR) - The most common indication for EBR is for the eyes of young people with bilateral retinoblastoma who have active or recurrent disease after chemotherapy and local therapy. However, patients with inherited diseases who received EBR therapy reported a 35% risk for second cancer.
• Brachytherapy - Brachytherapy involves placement of radioactive implants (plaques), usually on the sclera adjacent to the base of the tumor. It is used as a primary treatment or, more often, in patients with small tumors or in those who fail early therapy including previous EBR therapy.
• Therotherapy - Therotherapy involves the application of direct heat to the tumor, usually in the form of infrared radiation. It is also used for small tumors
• Laser fotokoagulasi - Laser photocoagulation is only recommended for small posterior tumors. An argon laser or a diode or xenon arc is used to control all blood supply to the tumor.
• Cryotherapy - Cryotherapy induces damage to the vascular endothelium with thrombosis and secondary infarction of tumor tissue by freezing it rapidly. Cryotherapy can be used as a primary therapy for small peripheral tumors or for recurrent small tumors previously treated with other methods.
• Systemic chemotherapy - Systemic chemotherapy has been at the forefront of treatment in the last decade, in the search for world conservation measures and to avoid the adverse effects of EBR therapy. General indications for chemotherapy for intraocular retinoblastoma include large and untreatable tumors with local therapy alone in children with bilateral tumors. It is also used in patients with unilateral disease when the tumor is small but can not be controlled with local therapy alone.
• Intra-arterial chemotherapy - Chemotherapy drugs are administered locally through thin catheters channeled through the groin, through the aorta and neck, directly into the optic vessels.
• Nano-particle chemotherapy - To reduce the adverse effects of systemic therapy, subconjuctival (local) injection of nanoparticle carriers containing chemotherapy agents (carboplatin) has been developed which has shown promising results in the treatment of retinoblastoma in animal models without side-effects..
• Chemoreduction - A combined approach using chemotherapy to initially reduce tumor size, and adjuvant focal treatments, such as transpupillary therapies, to control tumors.

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Prognosis

In developed countries, retinoblastoma has one of the best healing rates of all childhood cancers (95-98%), with more than nine out of every ten patients surviving to adulthood. In the UK, about 40 to 50 new cases are diagnosed each year.

A good prognosis depends on the child's initial presentation at a health facility. The late presentation of a child in a hospital is associated with a poor prognosis.

Survivors of hereditary retinoblastoma have a higher risk of developing other cancers later on.

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Epidemiology

Retinoblastoma presents with a cumulative lifetime rate of 1 case of retinoblastoma per 18,000 to 30000 live births worldwide. Higher incidence is noted in developing countries, it has been associated with low socioeconomic status and presence of human papilloma virus sequence in retinoblastoma tissue.

Nearly 80% of children with retinoblastoma are diagnosed before 3 years of age and diagnosis in children over 6 years is very rare. In the UK, bilateral cases usually occur within 14 to 16 months, while the diagnosis of unilateral cases peaks between 24 and 30 months.

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See also

• Eye cancer
• Eye check
• Protein Retinoblastoma

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References

src: webeye.ophth.uiowa.edu

External links

directory

• Inform the retinoblastoma dari MedlinePlus
NIH/UW GeneTests retinoblastoma
• Database Mutasi RB1
• Curlie Retinoblastoma (berdasarkan DMOZ)

Source of the article : Wikipedia