Histologic localization of sodium fluorescein in choroidal malignant melanomas

In seven patients we studied the distribution of fluorescein after intravenous injection histologically by a freeze-drying technique and by fluorescence microscopy in seven malignant melanomas of the choroid and correlated it with angiograms of these tumors. The tumor usually showed less fluorescence than the normal choroid. Hyperfluorescence was associated with areas that showed tumor necrosis with macrophages or accumulation of epithelioid melanoma cells. Diffuse hyperfluorescent areas in the fluorescein angiogram were associated with leakage of fluorescein from the choroid through the retinal pigment epithelium into the subretinal space. Leakage occasionally occurred with a normal-appearing retinal pigment epithelium. Drusen and cystic blebs of the retinal pigment epithelium led to pinpoint hyperfluorescence. Retinal cystoid degeneration had a multilocated hyperfluorescent pattern on the angiogram. Clinically we noted orange pigment in one patient. Histologically this pigmentation was caused by an accumulation of lipofuscin within proliferated retinal pigment epithelium. The retinal pigment epithelial barrier was intact in this area, with no observable fluorescein leakage into the subretinal space on either the angiogram or fluorescence microscopy.