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Retinoblastoma

Updated : March 12, 2024





Background

Retinoblastoma is a rare type of cancer that affects one out of every 18000 youngsters; however, it is the most prevalent primary intraocular tumor in adolescents, accounting for 3% of all juvenile cancer cases. After uveal melanoma, it is the second-highest common intraocular malignant cancer.

Survival rates in specialized treatment centers can reach ninety-five percent, with most patients retaining their vision, but they are lower in underdeveloped countries. Retinoblasts are the cells that make up retinoblastoma (scanty cytoplasm and basophilic cells containing hyperchromatic nuclei).

The majority of retinoblastomas are unclassified, although due to the creation of structures known as rosettes, variable levels of differentiation are present. The tumor might be endophytic (in the vitreous) with cancer cells spreading all across the eye, exophytic (in the subretinal region), or have a heterogeneous appearance.

When a tumor extends into the brain and subarachnoid space, it can cause optic nerve invasion. The metastatic spread affects the lungs, local lymph nodes, brain, liver, and bones.

Epidemiology

Retinoblastomas are the most prevalent primary intraocular cancer in children, accounting for three percent of all malignancies in this age group. It’s also the second-highest frequent malignant tumor in the eye. Retinoblastoma affects 1 in every 14000 to 1 in every 20000 births. Every year, 300 new cases are reported in the United States.

Retinoblastoma affects both men and women equally and has no sexual inclination. 90 percent of instances appear before the child reaches the age of three. The disease has a variable prevalence in different parts of the world. Research shows four cases per million in the US and six cases per million in Mexico. The countries with the highest rates include India and Africa.

Anatomy

Pathophysiology

The photoreceptor components of the inside layer of the retina give rise to retinoblastoma. Retinoblastomas are soft and brittle under the microscope and tend to overrun the blood supply, resulting in calcification and necrosis. Dissemination inside the retina and vitreous in the form of tiny, white nodules is prevalent due to its friability.

The appearance of retinoblastomas relies on the level of differentiation under the microscope. Small, spherical, closely packed cells with hyperchromatic nuclei and minimal cytoplasm make up undifferentiated retinoblastoma.

The Homer-Wright rosettes, which are mostly seen in other neuroblastic cancer such as medulloblastoma and neuroblastoma and infrequently seen in retinoblastomas; the Flexner-Wintersteiner rosettes, which are specific for retinoblastomas and seen in seventy percent of neoplasms; and the fleurettes, which are highly characteristic of well-differentiated cancers, have all been described.

Retinoblastoma spreads by a variety of mechanisms. Choroidal invasion opens a vast vascular network, which can act as a conduit for distant metastases. In advanced patients, the tumor extends directly into the orbit via the sclera. Retinoblastoma can spread to the local lymph nodes after invading the iris and ciliary body. Finally, retinoblastomas can invade the cerebral cavity and subarachnoid space by extending along the optic nerve.

Etiology

Retinoblastoma is caused by a mutation in the RB1 cancer suppressor genome, located at locus 14 on the long arm of chromosome 13 at (13q14). A tumor is formed when both copies of the Retinoblastoma 1 gene are altered. There is a 98 percent chance that the mutation in bilateral retinoblastomas is germline.

About five percent of retinoblastoma cases have a hereditary background. Retinoblastoma is spontaneous in 95% of instances, with sixty percent of patients having unilateral disease with a zero-linked genetic mutation. The remainder of the individuals have germline mutations and have developed numerous malignancies.

Heritable

All body cells in this kind of retinoblastoma have an alteration in one of the genes of, the RB1 gene. The malignant transformation of cells occurs when the other allele is mutated because of a mutagenic event. Most of these youngsters develop multifocal retinoblastoma and bilateral because of the mutation in all cells.

Nonocular cancers such as osteosarcoma, pineoblastoma, melanomas, and soft tissue sarcomas are common among heritable illness patients, and these cancers frequently arise in a specific age group. The probability of a second neoplasm is six percent, but it raises 5-fold when the initial tumor is treated with external radiation.

Non-Heritable

Retinoblastomas that are not heritable are unilateral and do not spread. Non-ocular malignancies are not a concern in these groups. It is non-heritable retinoblastomas in the case of unilateral retinoblastoma with negative family background, and the corresponding changes in each patient’s offspring and sibling are one percent. Nonhereditary retinoblastomas account for over ninety percent of unilateral retinoblastoma.

Genetics

Prognostic Factors

Patients with intraocular retinoblastomas, especially those with access to contemporary health care, have a good overall survival rate and prognosis of more than ninety-five percent of developed nations.

Extraocular extension, either through the optic nerve invasion or sclera, is the most crucial risk factor linked with a poor prognosis. Patients who survive bilateral retinoblastomas are more likely to acquire nonocular tumors later in life.

The latent period for the formation of the second tumor is typically nine months. In the first 30 years of life, external beam radiation shortens the inactive period and raises the chance of second cancer. Sarcoma is the most common type of the second neoplasm. Patients who develop sarcoma have a survival rate of fewer than 50%.

Clinical History

Physical Examination

Age group

Associated comorbidity

Associated activity

Acuity of presentation

Differential Diagnoses

Laboratory Studies

Imaging Studies

Procedures

Histologic Findings

Staging

Treatment Paradigm

by Stage

by Modality

Chemotherapy

Radiation Therapy

Surgical Interventions

Hormone Therapy

Immunotherapy

Hyperthermia

Photodynamic Therapy

Stem Cell Transplant

Targeted Therapy

Palliative Care

Medication

Media Gallary

References

https://www.ncbi.nlm.nih.gov/books/NBK545276/

https://www.ncbi.nlm.nih.gov/books/NBK13830/

Retinoblastoma

Updated : March 12, 2024




Retinoblastoma is a rare type of cancer that affects one out of every 18000 youngsters; however, it is the most prevalent primary intraocular tumor in adolescents, accounting for 3% of all juvenile cancer cases. After uveal melanoma, it is the second-highest common intraocular malignant cancer.

Survival rates in specialized treatment centers can reach ninety-five percent, with most patients retaining their vision, but they are lower in underdeveloped countries. Retinoblasts are the cells that make up retinoblastoma (scanty cytoplasm and basophilic cells containing hyperchromatic nuclei).

The majority of retinoblastomas are unclassified, although due to the creation of structures known as rosettes, variable levels of differentiation are present. The tumor might be endophytic (in the vitreous) with cancer cells spreading all across the eye, exophytic (in the subretinal region), or have a heterogeneous appearance.

When a tumor extends into the brain and subarachnoid space, it can cause optic nerve invasion. The metastatic spread affects the lungs, local lymph nodes, brain, liver, and bones.

Retinoblastomas are the most prevalent primary intraocular cancer in children, accounting for three percent of all malignancies in this age group. It’s also the second-highest frequent malignant tumor in the eye. Retinoblastoma affects 1 in every 14000 to 1 in every 20000 births. Every year, 300 new cases are reported in the United States.

Retinoblastoma affects both men and women equally and has no sexual inclination. 90 percent of instances appear before the child reaches the age of three. The disease has a variable prevalence in different parts of the world. Research shows four cases per million in the US and six cases per million in Mexico. The countries with the highest rates include India and Africa.

The photoreceptor components of the inside layer of the retina give rise to retinoblastoma. Retinoblastomas are soft and brittle under the microscope and tend to overrun the blood supply, resulting in calcification and necrosis. Dissemination inside the retina and vitreous in the form of tiny, white nodules is prevalent due to its friability.

The appearance of retinoblastomas relies on the level of differentiation under the microscope. Small, spherical, closely packed cells with hyperchromatic nuclei and minimal cytoplasm make up undifferentiated retinoblastoma.

The Homer-Wright rosettes, which are mostly seen in other neuroblastic cancer such as medulloblastoma and neuroblastoma and infrequently seen in retinoblastomas; the Flexner-Wintersteiner rosettes, which are specific for retinoblastomas and seen in seventy percent of neoplasms; and the fleurettes, which are highly characteristic of well-differentiated cancers, have all been described.

Retinoblastoma spreads by a variety of mechanisms. Choroidal invasion opens a vast vascular network, which can act as a conduit for distant metastases. In advanced patients, the tumor extends directly into the orbit via the sclera. Retinoblastoma can spread to the local lymph nodes after invading the iris and ciliary body. Finally, retinoblastomas can invade the cerebral cavity and subarachnoid space by extending along the optic nerve.

Retinoblastoma is caused by a mutation in the RB1 cancer suppressor genome, located at locus 14 on the long arm of chromosome 13 at (13q14). A tumor is formed when both copies of the Retinoblastoma 1 gene are altered. There is a 98 percent chance that the mutation in bilateral retinoblastomas is germline.

About five percent of retinoblastoma cases have a hereditary background. Retinoblastoma is spontaneous in 95% of instances, with sixty percent of patients having unilateral disease with a zero-linked genetic mutation. The remainder of the individuals have germline mutations and have developed numerous malignancies.

Heritable

All body cells in this kind of retinoblastoma have an alteration in one of the genes of, the RB1 gene. The malignant transformation of cells occurs when the other allele is mutated because of a mutagenic event. Most of these youngsters develop multifocal retinoblastoma and bilateral because of the mutation in all cells.

Nonocular cancers such as osteosarcoma, pineoblastoma, melanomas, and soft tissue sarcomas are common among heritable illness patients, and these cancers frequently arise in a specific age group. The probability of a second neoplasm is six percent, but it raises 5-fold when the initial tumor is treated with external radiation.

Non-Heritable

Retinoblastomas that are not heritable are unilateral and do not spread. Non-ocular malignancies are not a concern in these groups. It is non-heritable retinoblastomas in the case of unilateral retinoblastoma with negative family background, and the corresponding changes in each patient’s offspring and sibling are one percent. Nonhereditary retinoblastomas account for over ninety percent of unilateral retinoblastoma.

Patients with intraocular retinoblastomas, especially those with access to contemporary health care, have a good overall survival rate and prognosis of more than ninety-five percent of developed nations.

Extraocular extension, either through the optic nerve invasion or sclera, is the most crucial risk factor linked with a poor prognosis. Patients who survive bilateral retinoblastomas are more likely to acquire nonocular tumors later in life.

The latent period for the formation of the second tumor is typically nine months. In the first 30 years of life, external beam radiation shortens the inactive period and raises the chance of second cancer. Sarcoma is the most common type of the second neoplasm. Patients who develop sarcoma have a survival rate of fewer than 50%.

https://www.ncbi.nlm.nih.gov/books/NBK545276/

https://www.ncbi.nlm.nih.gov/books/NBK13830/

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