False-positive magnetic resonance imaging of a metastatic carcinoma simulating a malignant melanoma.

Previous studies have shown the value of magnetic resonance imaging (MRI) in the diagnosis of malignant melanoma of the choroid. We describe the case of a patient with a choroidal mass whose MRI study was characteristic of malignant melanoma. Subsequently the eye was enucleated. However, on histopathologic examination, the mass was a metastatic carcinoma to the choroid. This false-positive study makes us question the value of MRI in the diagnosis of malignant melanoma of the choroid.