A 60-year-old presents with a unilateral dark-brown choroidal mass, 8 mm in diameter, with low internal reflectivity on A-scan ultrasound and 'choroidal excavation' (acoustic shadowing). What is the most likely diagnosis and what is the most important prognostic factor for metastasis?

• A Choroidal haemangioma; prognosis is excellent
• B Choroidal metastasis; primary breast cancer most likely
• C Choroidal osteoma; calcification on B-scan confirms diagnosis
• D Choroidal melanoma; largest basal diameter (LBD) is the most important prognostic factor for metastasis ✓

Explanation

Uveal (choroidal) melanoma is the most common primary intraocular malignancy in adults. A-scan low internal reflectivity and 'choroidal excavation' (shadowing) on B-scan are characteristic. The largest basal diameter (LBD) and tumour thickness are the most important factors for metastatic risk, along with cytogenetic factors (monosomy 3, chromosome 8q gain). Choroidal haemangioma shows high internal reflectivity. Choroidal metastasis is usually bilateral and from breast/lung; it shows irregular, non-pigmented flat lesions.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.