Sixty-six percent of the cases are seen in children less than 3 years old, and it is rarely seen after 6 years old.
Tumor arises from the retina and extends into the vitreous cavity.
Spreads extraocularly via infiltration into the optic nerve with direct extension via the subarachnoid space around optic nerve. Can also spread to the choroid plexus where it can metastasize hematogenously. Once tumor fills the orbit it also can spread directly through the skull and brain. Metastasizes to brain, bone, liver, kidney, lung, testes, and lymph nodes. If treated with radiation patient is at risk for osteosarcoma 10 years later.