The retina is made up of nerve tissue that senses light as it comes through the front of the eye. The retina sends signals through the optic nerve to the brain, where they are interpreted as images.
Retinoblastoma occurs when nerve cells in the retina develop genetic mutations that cause them to proliferate unchecked and escape the body’s mechanisms for eliminating them. The resulting mass of accumulating cells turns into a malignant tumor.
The disease often affects only one eye in babies and children. However, about 40% of children with retinoblastoma develop cancer in both eyes. If left untreated, retinoblastoma cells can spread to other parts of the body, including the brain.
Some children inherit the genetic mutation that leads to retinoblastoma from a parent. In most cases, however, there is no family history of the disease.
Types of Retinoblastoma
There are two types of this eye cancer, based on when and where the genetic mutation occurs.
Hereditary retinoblastoma. In about 40% of children with retinoblastoma, the gene mutation is present in most or all cells in the body, either as a result of inheriting the mutation from a parent or developing the mutation very early in fetal development.
Children with this form of retinoblastoma tend to develop the disease at an earlier age and often develop multiple tumors in both eyes.
Later in life, these individuals can pass on the mutation to their children, and they are at increased risk of developing other types of cancer, including:
- Pineoblastoma, a brain cancer that arises in or around the pineal gland, which usually arises by age 5 or 6.
- Melanoma, an aggressive form of skin cancer usually seen in younger adults
- Osteosarcoma, a type of bone cancer that arises in the teenage years
- Soft tissue sarcomas, cancers of soft tissues such as muscle, which usually appear in the teenage years
Non-hereditary retinoblastoma. In about 60% of children with retinoblastoma, the gene mutation develops in only one cell of one eye and is not present in any other cells in the body. In most cases, this mutation is thought to arise as a random mistake made by the cell while copying the DNA. A child who has somatic retinoblastoma develops only one tumor in one eye, is not at increased risk for other cancers, and does not pass on this mutation to their children. Non-hereditary retinoblastoma is often found in slightly older children.
Signs and Symptoms of Retinoblastoma
Because retinoblastoma mostly affects infants and small children, symptoms such as pain are rare, and young children rarely complain of vision loss. Retinoblastoma is almost always discovered when the child’s caregiver or pediatrician notices unusual changes in a child’s eye.
The most common first sign of retinoblastoma is a visible whiteness in the pupil called leukocoria, meaning “white pupil” and sometimes known as “cat's eye reflex.” It is most noticeable in dim light or in photographs taken with a flash.
The second most common sign of retinoblastoma is the drifting in or out of an eye, a condition called strabismus, or crossed eyes. While retinoblastoma is a rare cause of strabismus, it needs to be ruled out in children presenting with this condition.
Uncommon signs and symptoms of retinoblastoma include:
- A different color in each iris, the colored part of the eye
- A pupil that doesn’t get smaller when exposed to bright light
- Bleeding in the front part of the eye
- Bulging of the eye
- Eye pain
- Redness of the white part of the eye
- Redness, soreness, or swelling of the eyelids
- Vision loss in older children where vision can be measured
Many of these signs and symptoms are more likely to be caused by something other than retinoblastoma, but it’s important for parents to be aware of any unusual symptoms and to make an appointment to see a pediatrician if they have any concerns about their child’s health.
