Fact-sheet: Retinoblastoma
Updated on 09/17/2021 at 12:16 PM
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Definition
Malignant retinal tumor derived from the neuroectoderm. Epidemiology: the most common malignant intraocular tumor in children. Incidence of 1/15,000 to 30,000 births. Mean age at diagnosis 13 months. Etiology: >Sporadic non-familial form: 60% >Hereditary familial form: 40% Location: >Unilateral - 70-75% >Bilateral - 25/40% >Trilateral - rare: see below. Heredity/genetics (10%). Natural history: >Endophytic: internal intraocular growth into the vitreous. >Exophytic: external growth into the subretinal space. >Diffuse infiltrative: "plaque-like" along the retina, rare (2%), without calcifications, mimicking inflammatory involvement. Trilateral retinoblastoma: bilateral ocular involvement associated with a midline neuroblastic tumor: pineal (80%) > suprasellar (20%).
Clinical features
-Leukocoria: most suggestive sign (60%)
-Other: strabismus, severe decrease in visual acuity, inflammatory signs
-Less common: anisocoria, glaucoma, nystagmus, cataract.
Ultrasound
Irregular, heterogeneous intraocular mass, with posterior acoustic shadowing ++ (calcified).
Does not assess extraocular extension.
CT
Irregular intraocular mass, calcified ++ (95%).
Variable enhancement of the non-calcified component after contrast injection.
MRI
>T1: (mildly) hyperintense compared to the vitreous.
>T2: hypointense compared to the vitreous. Retinal detachment ++
>T2 GE: calcifications, hemorrhagic changes.
>T1 C+: moderate to marked enhancement. Assessment ++ of extension, which determines prognosis: extension to the optic nerve, to the anterior segment (sign of aggressiveness).
Search over the entire brain ++: pineal or suprasellar location?
Management
-Reduction chemotherapy: neoadjuvant.
-External beam radiotherapy: large tumor + extension
-In situ radiotherapy: (I-125) - small tumor
-Enucleation: tumor extension ++
-Cryotherapy/photocoagulation.
Classification
>Reese-Ellsworth classification: size, location, number of foci.
Relevant for radiotherapy.
Differential diagnosis
-Retinal astrocytoma: rare, +/- association with tuberous sclerosis.
-Optic drusen: idiopathic dystrophic calcifications, incidental finding.
-Retinocytoma: rare benign tumor variant.
-Foreign bodies: metallic ones most common, history of ocular trauma.
-Ocular toxocariasis: sclerosing endophthalmitis due to toxocara canis. No calcification. Enhancement of the uvea and sclera.