Choroidal Melanoma Board Review
Master choroidal melanoma board clues: shape, orange pigment, ultrasound findings, key mimics and COMS-based management.
Which part of the uveal tract is the most common site for uveal melanoma?
Choroidal Melanoma in 30 Seconds
Choroidal melanoma is the most common primary intraocular malignancy in adults and the second most common site of melanoma after the skin. It arises from uveal melanocytes and may threaten vision, the globe and life through metastatic disease. Early recognition matters because subtle lesions can mimic benign choroidal tumors.
Classic Clinical Features
- Shape: dome-shaped early, developing a mushroom or collar-button configuration after rupture through Bruch membrane. Exam relevance: mushroom shape strongly supports melanoma.
- Color: pigmented or amelanotic. Exam relevance: lack of pigment does not exclude melanoma.
- Orange pigment: orange lipofuscin pigment overlying the tumor. Exam relevance: lipofuscin is a key suspicious feature.
- Subretinal fluid: exudative retinal detachment. Exam relevance: fluid raises concern for active tumor growth.
- Size: thickness greater than 2 mm, larger basal diameter than a nevus. Exam relevance: increasing size favors melanoma over nevus.
- Symptoms: blurred vision, photopsia, visual field loss or asymptomatic. Exam relevance: symptoms depend on tumor location and associated fluid.
- Risk factors: light skin, light iris color and ocular or oculodermal melanocytosis, also called nevus of Ota. Exam relevance: predisposing factors are occasionally tested.
Diagnosis and Imaging
- B-scan ultrasound: low-to-medium internal reflectivity, acoustic hollowness and choroidal excavation. Exam relevance: these findings support melanoma over hemangioma.
- Fundus exam and photography: document tumor size and growth. Exam relevance: serial growth strongly supports malignancy.
- Fluorescein angiography: double circulation pattern in some tumors. Exam relevance: this finding can support the diagnosis but is not required.
- Diagnosis is largely clinical, and biopsy is rarely needed. Exam relevance: do not make biopsy the routine diagnostic step.
4 Facts Exams Always Ask
- Choroidal melanoma is the most common primary intraocular malignancy in adults and arises from uveal melanocytes.
- Mushroom or collar-button configuration occurs when the tumor ruptures through Bruch membrane.
- B-scan typically shows low-to-medium internal reflectivity with acoustic hollowness.
- The Collaborative Ocular Melanoma Study established plaque brachytherapy for medium tumors and enucleation for large tumors, with no survival benefit shown for pre-enucleation radiotherapy.
The Classic Trap
Differentiate melanoma from choroidal nevus and circumscribed choroidal hemangioma. Melanoma shows low-to-medium reflectivity and acoustic hollowness, while hemangioma typically shows high reflectivity. For nevus, apply TFSOM-UHHD: thickness, fluid, symptoms, orange pigment, margin near disc, ultrasound hollowness, absent halo and absent drusen. Review the Choroidal Nevus lesson with this differential.
Clinical Pearl
The Collaborative Ocular Melanoma Study, or COMS, established plaque brachytherapy as the standard globe-sparing treatment for appropriate medium tumors, with survival comparable to enucleation. Metastasis is hematogenous and favors the liver, which is the first site of spread in the large majority of patients with metastatic uveal melanoma. This drives systemic surveillance.
Checkpoint 1
A mushroom or collar-button shape in choroidal melanoma suggests rupture through which structure?
Checkpoint 2
Which imaging feature is more typical of choroidal melanoma than choroidal hemangioma on ultrasound?
A patient has a pigmented choroidal mass with a dome-shaped configuration, orange pigment and surrounding subretinal fluid. B-scan shows low-to-medium internal reflectivity with acoustic hollowness. What diagnosis should be highest on the differential?
Which shape is classically seen in many untreated choroidal melanomas?
Sources & Reviewer Info
References
- AAO BCSC Section 4: Ophthalmic Pathology and Intraocular Tumors.
- Shields CL, Shields JA. Clinical Ocular Oncology.
- AAO EyeWiki: Choroidal Melanoma.
- Collaborative Ocular Melanoma Study reports.
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