Retinoblastoma in children

Retinoblastoma in children

Introduction

Although uncommon and occurring in only 1 in 18,000 to 20,000 live births, retinoblastoma is the most common tumor of the eye and usually occurs in the first few years of a child's life and most cases (90%) occur before age 5. Although not as common, older children can get retinoblastoma too, and they usually complain of eye pain or decreased vision in the affected eye. Retinoblastoma is responsible for causing 5% of the cases of childhood blindness.

Retinoblastoma in children

There is a tumor suppressor gene on the long arm of chromosome 13 and it is the retinoblastoma gene. The presence of this gene helps to suppress retinoblastoma from forming by forming a protein that is though to help regulate cell growth. If both copies of the gene are mutated or absent, then retinoblastoma can form. In familial or genetic forms of retinoblastoma, one copy of the defective gene is usually inherited and the other one becomes mutated. In non hereditary cases of retinoblastoma, both genes become mutated.

Retinoblastoma is commonly found during routine screening in high risk children, specifically newborns that have other family members with retinoblastoma. Other infants are diagnosed when they are found to not have a red reflex (or red eye) during a routine well baby checkup or if the child's eyes appear different in a photograph. Instead, they have leukocoria (cat's eye reflex) or a white pupillary reflex. Later symptoms can include redness or inflammation of the eye, strabismus or abnormalities of the pupil. Further evaluation and testing include an evaluation by a pediatric ophthalmologist and an ultrasound or CT scan of the eye. Other testing may also be required if it is though that the tumor has spread outside the eye. Retinoblastoma can be either unilateral, affecting only one eye, or it can be bilateral, affecting both eyes. Treatments depend on the size of the tumor and whether vision can be preserved, and can include laser photocoagulation or cryotherapy, external beam radiation, multi drug chemotherapy, or in some cases, surgery or enucleation (although this isn't routinely recommended anymore) if the tumor is very advanced or if vision can not be preserved. Outcomes are in general very good, especially if the retinoblastoma is only affecting one eye. Children with retinoblastoma are also at risk of developing secondary malignancies, especially osteosarcoma, a malignant bone tumor that can present with pain and swelling of the affected bone or joint.

Retinoblastoma occurs due to mutations in a tumor suppressor gene (called RB1) located on chromosome #13. Two mutations (or gene changes) are necessary to "knock-out" this gene, and cause uncontrolled cell growth. In inherited retinoblastoma (40 percent of the cases), the first mutation is inherited from a parent, while the second occurs during the development of the retina. In sporadic retinoblastoma (60 percent of the cases), both mutations occur during development of the retina. Sporadic means "occurs by chance." Alterations in the RB1 gene have also been found in other tumors, including osteosarcoma and breast ...