Retinoblastoma

Michael P. D'Alessandro, M.D.
Peer Review Status: Internally Peer Reviewed

Etiology/Pathophysiology:
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. It is the most common malignant intraocular tumor in kids, causeing 5% of childhood blindness and 1% of childhood cancer deaths.

Pathology:
Not applicable

Imaging Findings:
On CT is a well defined orbital calcified mass that does not enhance. Metastatic lesion are less frequently calcified and often enhance. Orbital extension can be seen as thickening of the optic nerve.

DDX:
Intraocular Calcification

• Foreign body
• Post inflammatory atrophy of globe
• Toxocara canis granulomas
• Retrolental fibroplasia
• Chronic hypercalcemia
• Tuberous Sclerosis
• Cataracts
• Coats disease - congenital vascular anomaly of retina

References:
See References Chapter.

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