Osseous Choristoma of the Choroid (Case 1)
Because it could have also been an amelanotic malignant melanoma, B-mode ultrasonography was performed and revealed a flat lesion at the level of the choroid. The persistent echoes, even at low sensitivity levels, were typical of tissue containing calcium (see right figure); hence, the diagnosis of a bone tumor of the orbit could be made.
A bone tumor of the choroid is not a common finding, but B-scan ultrasonography can be invaluable in making the diagnosis. An 11-year old asymptomatic girl presented with 20/25 visual acuity in the left eye. Ophthalmoscopy revealed a large, slightly elevated, well-defined creamy yellow lesion shown on the left. Because of its position near and around the disc, it was thought to be an osseous choristoma or bone tumor of the choroid.
