Synonyms
retinal tumor
What is a retinoblastoma?
A retinoblastoma is a tumor of the retina (at the back of the eye). This tumor is genetic, i.e. hereditary. It usually occurs in childhood and is malignant.
How common is retinoblastoma?
Retinoblastoma is a congenital tumor or it develops in early childhood. It is the most common eye tumor in childhood. In about one third of the cases both eyes are affected.
More than one tumor can also develop in one eye. In most cases the tumor develops before the age of 3. The affected children are often free of symptoms, i.e. they do not express any pain.
Occasionally it can happen that the children squint with a retinoblastoma. For this reason, the fundus of the eye is always examined during the initial examination (see fundus examination) in order to exclude such a tumor. Also an inflammation of the eye, which exists for a long time, can be an indication of a retinal tumor.
However, the typical recognition feature of retinoblastoma is of a completely different nature: the parents come to the doctor with the child because they noticed a difference in the pupils in photos of the child. The children have a normal, red pupil and a different looking, whitish pupil. The medical term for this is leukocoria (Greek leukos = white, kore = pupil).
At this stage, the retinoblastoma tumor is already so far advanced that it fills a large part of the vitreous cavity, which extends from the lens to the rear pole of the eye. It is also called a cat’s eye. The diagnosis of retinoblastoma is made by the ophthalmologist by means of the ocular fundus mirror.
This is done by looking through the pupil and lens into the back of the eye with a light source and a magnifying glass. Preferably, the vitreous cavity and retina are examined. The tumor can be easily recognized by its bulbous, whitish structure.
If the tumor becomes too large, it breaks into the vitreous cavity. Parts of the tumor may float in the vitreous cavity. Ultrasound, X-ray or a CT scan of the eye can also be performed.
Here, calcification foci are typically seen. However, these methods are more likely to be used for doubtful diagnoses and are not part of the routine. Computer tomography can also rule out scattering along the optic nerve.
As explained above, the retinoblastoma tumor is already well advanced and therefore relatively large at the time of diagnosis. In these cases the eye must be removed. During this so-called enucleation, the largest possible section (1 cm) of the optic nerve must be removed to avoid possible scattering of tumor cells.
Smaller tumors can also be treated with chemotherapy. In this case, the tumor usually shrinks somewhat and the sewing on of a radiating body is possible. This belongs to the large group of radiotherapy procedures.
Tumors that are still small when diagnosed can be treated with such a radiating body from the beginning. If these retinoblastoma tumors are located quite far out on the retina, cold therapy (cryotherapy) can be used. Since retinoblastoma is hereditary, it cannot be prevented.
However, regular follow-up examinations help to detect a possible recurrence of retinoblastoma at an early stage. These follow-ups must be carried out for 5 years. The second eye must also be thoroughly examined.
To ensure this, the children should be put under a short anaesthetic. The pupils are dilated with special eye drops. During the first two years, the check-ups are carried out every three months, then every six months or annually.
Retinoblastoma mainly affects children. This is due to the fact that it is a hereditary disease passed on from parent to child. If the child possesses the affected genes, retinoblastoma often develops within the first 3 years of life.
In childhood it is the most common eye tumor, which is why it is very well researched. Researchers have discovered that the gene for a retinoblastoma is located on the 13th chromosome, more precisely on the locus chromosome 13q14. This chromosome contains all information for the tumor suppressor retinoblastoma protein Rb.
A tumor suppressor is a protein that controls the growth of a cell.If the DNA is damaged or mutated (changed), they can send the cell into self-destruction, thus preventing further damage. In retinoblastoma, however, this tumor suppressor Rb is altered by a mutation and has lost its physiological function. As a result, this natural defense function is missing and further mutations are not destroyed, so that the cell can continue to grow uncontrolled. This leads to the development of a tumor.
