Fact-sheet: Uveal melanoma
Updated on 10/07/2017 at 8:07 AM
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Definition
Melanoma arising from the choroid.
Most common malignant orbital tumor, though still rare.
The choroid is the vascular layer adjacent to the retina. It may harbor nevi (benign tumors) or melanomas (malignant tumors).
Clinical features
Visual symptoms: decreased visual acuity, photopsia, with or without associated retinal detachment.
May be an incidental finding during routine ophthalmologic examination.
Not visible to the naked eye, and painless.
Can occur at any age (with a peak around age 50).
The causal link with UV exposure is not clearly established.
About 90% of metastases are hepatic.
Ultrasound
Convex intravitreal image with low echogenicity and an area of even lower echogenicity at its posterior aspect, due to attenuation by the tumor tissue and the presence of a choroidal excavation.
CT
Spontaneous intravitreal hyperdensity (50-80 HU), homogeneous,
well-defined, enhancing after contrast injection. Allows assessment of
tumor size and detection of significant extrascleral
extension, orbital or optic nerve involvement.
MRI
T1-weighted sequences before and after injection, T2-weighted:
The lesion appears hyperintense on T1 and on proton density, markedly hypointense on T2, with marked but variable enhancement.
Melanin, owing to its paramagnetic properties,
leaves little doubt as to the highly characteristic nature of this signal, which excludes other potential diagnoses (hemangioma, vascular-type tumor).
Management
Management decided at multidisciplinary tumor board, depending on tumor size.
Enucleation or conservative treatment with iodine-125 plaque brachytherapy or proton therapy.
Long-term follow-up, as metastatic risk remains high several years after treatment.
Management of metastases (poor prognosis) with chemotherapy and immunotherapy.
Differential diagnosis
-Choroidal metastases
-Choroidal nevus
-Choroidal hemangioma
-Choroidal osteoma
