Nonfluorescent malignant melanoma of the choroid diagnosed with the radioactive phosphorus uptake test.

A 57-year-old white woman presented with a small malignant melanoma of the choroid in the macular area of the right eye. The lesion failed to produce a visual field defect or to show fluorescence with angiography, but the radioactive phosphorus uptake(P) test was positive. Histologically, the retinal pigment epithelium was intact over the tumor and the sensory retina was normal. This unusual finding was the most likely explanation for the normal visual field. The intact retinal pigment epithelium over this nonfluroescent melanoma suggests that the destruction of the retinal pigment epithelium occurring with most choroidal melanomas may partially explain why these tumors usually demonstrate fluorescence. This case emphasizes the great accuracy of the P test for diagnosing small malignant tumors of the choroid, even before other popular diagnostic modalities indicate the malignancy of the lesion.