Rare form of cancer rapidly developing from immature cells of retina, most commonly in young children. Also see appropriate Cancer programs.Encyclopedia Entry for Retinoblastoma :Retinoblastoma. Retinoblastoma is caused by a mutation in a gene that controls how cells divide. As a result, cells grow out of control and become cancerous. In about half the cases, this mutation develops in a child whose family has never had eye cancer. In other cases, the mutation occurs in several family members. If the mutation runs in the family, there is a 50% chance that an affected person's children will also have the mutation. These children will therefore have a high risk of developing retinoblastoma themselves. The cancer most often affects children younger than 7 years old. It is most commonly diagnosed in children 1 to 2 years old.One or both eyes may be affected. The pupil of the eye may appear white or have white spots. A white glow in the eye is often seen in photographs taken with a flash. Instead of the typical 'red eye' from the flash, the pupil may appear white or distorted. Other symptoms can include: Crossed eyes Double vision Eyes that do not align Eye pain and redness Poor vision Differing iris colors in each eye If the cancer has spread, bone pain and other symptoms may occur.The health care provider will perform a complete physical exam, including an eye exam. The following tests may be done: CT scan or MRI of the head Eye exam with dilation of the pupil Ultrasound of the eye ( head and eye echoencephalogram ).Treatment options depend on the size and location of the tumor: Small tumors may be treated by laser surgery or cryotherapy (freezing). Radiation is used for both a tumor that is within the eye and for larger tumors. Chemotherapy may be needed if the tumor has spread beyond the eye. The eye may need to be removed (a procedure called enucleation) if the tumor does not respond to other treatments. In some cases, it may be the first treatment.If the cancer has not spread beyond the eye, almost all people can be cured. A cure, however, may require aggressive treatment and even removal of the eye in order to be successful. If the cancer has spread beyond the eye, the likelihood of a cure is lower and depends on how the tumor has spread.Blindness can occur in the affected eye. The tumor can spread to the eye socket through the optic nerve. It may also spread to the brain, lungs, and bones.Call your provider if signs or symptoms of retinoblastoma are present, especially if your child's eyes look abnormal or appear abnormal in photographs.Genetic counseling can help families understand the risk for retinoblastoma. It is especially important when more than one family member has had the disease, or if retinoblastoma occurs in both eyes.Tumor - retina; Cancer - retina; Eye cancer - retinoblastoma.Eye Eye.Cheng KP. Ophthalmology.