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What is retinoblastoma?

Retinoblastoma is a malignant tumour that starts in cells of the retina in the eye. Malignant means that it can spread, or metastasize, to other parts of the body.

The retina is part of the eye, which is the organ that lets you see. The retina is the inner layer of cells in the back part of the eyeball. It is made up of special nerve cells that are sensitive to light.

When the eyes are developing, they have cells called retinoblasts. These cells divide into new cells and fill the part of the eye that will become the retina. Sometimes there is a change, or mutation, in a gene in a retinoblast called the retinoblastoma (RB1) gene. This mutated gene causes the retinoblast to change and grow out of control. The abnormal cells caused by this mutation form a tumour called retinoblastoma. Retinoblastoma is the most common type of eye cancer in children. It is usually found in children under the age of 2 years.

Other types of cells in the eye can sometimes change and cause non-cancerous, or benign, conditions or tumours that have some of the same symptoms as retinoblastoma. These include congenital cataract, pseudoretinoblastoma, retinopathy of prematurity (ROP) and retinocytoma.

Diagram of the eyeball


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