General Information About Retinoblastoma
Key Points for This Section
- Retinoblastoma is a disease in which malignant (cancer) cells form in the tissues of the retina.
- Retinoblastoma occurs in heritable and nonheritable forms.
- Treatment for both forms of retinoblastoma should include genetic counseling.
- A child who has heritable retinoblastoma has an increased risk of trilateral retinoblastoma and other cancers.
- Signs and symptoms of retinoblastoma include "white pupil" and eye pain or redness.
- Tests that examine the retina are used to detect (find) and diagnose retinoblastoma.
- Certain factors affect prognosis (chance of recovery) and treatment options.
Although retinoblastoma may occur at any age, it usually occurs in children younger than 5 years, most often younger than 2 years. The cancer may be in one eye (unilateral) or in both eyes (bilateral). Retinoblastoma rarely spreads from the eye to nearby tissue or other parts of the body.
A child is thought to have the heritable form of retinoblastoma when one of the following is true:
- There is a family history of retinoblastoma.
- There is a certain mutation (change) in the RB1 gene. The mutation in the RB1 gene may be passed from the parent to the child or it may occur at the time of conception.
- There is more than one tumor in the eye or there is a tumor in both eyes.
- There is a tumor in one eye and the child is younger than 1 year.
After diagnosis and treatment in a child with heritable retinoblastoma, new tumors may continue to form for a few years. Regular eye exams to check for new tumors are usually done every 2 to 4 months for at least 28 months.
Nonheritable retinoblastoma is retinoblastoma that is not the heritable form. Most cases of retinoblastoma are the nonheritable form.
Parents should receive genetic counseling (a discussion with a trained professional about genetic diseases) to discuss whether genetic testing is needed and the risk of retinoblastoma for the child's brothers or sisters.
A child with heritable retinoblastoma has an increased risk of a pineal tumor in the brain. When retinoblastoma and a brain tumor occur at the same time it is called trilateral retinoblastoma. The brain tumor is usually diagnosed between 20 and 36 months of age. Regular screening using MRI (magnetic resonance imaging) every 6 months for 5 years may be done for a child thought to have heritable retinoblastoma or for a child with retinoblastoma in one eye and a family history of the disease. CT scans (computerized tomography) should not be used for routine screening to avoid exposing the child to ionizing radiation.
- Pupil of the eye appears white instead of red when light shines into it. This may be seen in flash photographs of the child.
- Pain or redness in the eye.
- Eyeball is larger than normal.
- Colored part of the eye and pupil look cloudy.
- Eyes appear to be looking in different directions (lazy eye).
The following tests and procedures may be used:
- Physical exam and history : An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken. The doctor will ask if there is a family history of retinoblastoma.
- Eye exam with dilated pupil: An exam of the eye in which the pupil is dilated (opened wider) with medicated eye drops to allow the doctor to look through the lens and pupil to the retina. The inside of the eye, including the retina and the optic nerve, is examined with a light. Depending on the age of the child, this exam may be done under anesthesia.
There are several types of eye exams that are done with the pupil dilated:
- Ophthalmoscopy : An exam of the inside of the back of the eye to check the retina and optic nerve using a small magnifying lens and a light.
- Slit-lamp biomicroscopy : An exam of the inside of the eye to check the retina, optic nerve, and other parts of the eye using a strong beam of light and a microscope.
- Fluorescein angiography : A procedure to look at blood vessels and the flow of blood inside the eye. An orange fluorescent dye called fluorescein is injected into a blood vessel in the arm and goes into the bloodstream. As the dye travels through blood vessels of the eye, a special camera takes pictures of the retina and choroid to find any blood vessels that are blocked or leaking.
- Ultrasound exam of the eye: A procedure in which high-energy sound waves (ultrasound) are bounced off the internal tissues of the eye to make echoes. Eye drops are used to numb the eye and a small probe that sends and receives sound waves is placed gently on the surface of the eye. The echoes make a picture of the inside of the eye and the distance from the cornea to the retina is measured. The picture, called a sonogram, shows on the screen of the ultrasound monitor. The picture can be printed to be looked at later.
- MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body, such as the eye. This procedure is also called nuclear magnetic resonance imaging (NMRI).
- CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, such as the eye, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
- Bone scan : A procedure to check if there are rapidly dividing cells, such as cancer cells, in the bone. A very small amount of radioactive material is injected into a vein and travels through the bloodstream. The radioactive material collects in the bones and is detected by a scanner that also takes a picture of the body. Areas of bone with cancer show up brighter in the picture because they take up more radioactive material than normal bone cells do.
Retinoblastoma can usually be diagnosed without a biopsy.
When retinoblastoma is in one eye, it sometimes forms in the other eye. Exams of the unaffected eye are done until it is known if the retinoblastoma is the heritable form.
- Whether the cancer is in one or both eyes.
- The size and number of tumors.
- Whether the tumor has spread to the area around the eye, to the brain, or to other parts of the body.
- Whether there are symptoms at the time of diagnosis, for trilateral retinoblastoma.
- The age of the patient.
- How likely it is that vision can be saved in one or both eyes.
- Whether a second type of cancer has formed.