Melanocytoma of the choroid: angiographic and histopathologic findings.

A juxtapapillary choroidal melanocytoma that was clinically confused with a choroidal melanoma is described. The clinical examination of a 40-year-old female patient included ultrasonography, fluorescein, and indocyanine green angiography. Histopathologic and immunohistochemical study of the enucleated eye resulted in the identification of a markedly pigmented, 3.8 mm elevated choroidal melanocytic tumor observed nasally to the disk. A-scan ultrasonography showed a high initial spike with a low to medium internal reflectivity with decreasing amplitude. On fluorescein angiography, the tumor was surrounded by a rim of retinal pigment epithelium depigmentation with a well-defined comet-tail. The lesion was hypofluorescent in the early phases of the indocyanine green angiogram, but from the late venous phase appeared ill-defined hyperfluorescence. Histopathologic study revealed a juxtapapillary choroidal melanocytoma The pigmented tumor cells stained positive for HMB45 and vimentin but negative for S100, GFAP, NSE, and MNF116. No tumor cells stained positive for the proliferation marker Ki67. These findings conclude that choroidal melanocytoma may mimick choroidal melanoma. Abnormalities on fluorescein angiography may be a clinical hint to suspect a pigmented tumor different from a choroidal melanoma.