A 55-year-old with a suspected choroidal melanoma undergoes B-scan ultrasonography. Which set of features on B-scan is MOST characteristic of malignant choroidal melanoma?
- A High internal reflectivity, homogeneous echoes, no shadowing
- B Flat lesion, high internal reflectivity, calcification
- C Collar-stud shape, low-to-medium internal reflectivity, orbital shadowing, choroidal excavation ✓
- D Dome shape, uniformly high echoes, no orbital shadowing
Correct answer: C. Collar-stud shape, low-to-medium internal reflectivity, orbital shadowing, choroidal excavation
Explanation
Choroidal melanoma on B-scan typically shows a collar-stud (mushroom) configuration caused by Bruch's membrane rupture, low-to-medium internal reflectivity due to vascularity, orbital shadowing (acoustic shadowing behind the mass), and choroidal excavation at the base. High internal reflectivity and calcification suggest choroidal haemangioma or calcified naevus. A flat lesion with calcification is more consistent with retinoblastoma (in children) or choroidal osteoma.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
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Written and medically reviewed by the StethoPrep medical team.