Histogenesis of Malignant Melanomas of the Uvea

A histopathologic study of nevi of the choroid and ciliary body was undertaken to ascertain their cytologic characteristics and their effect on the overlying pigment epithelium and sensory retina. Most of the nevi were very small, and 90% measured less than 4 disc diameters in their greatest diameter. Because of their small size, frequent lack of much pigmentation, and occurrence in eyes with opaque media, 90% escaped detection clinically. In eight of the ten cases in which the nevi were discovered clinically, the lesions were mistaken for malignant melanoma and the eyes were enucleated. Study of the cytologic characteristics of uveal nevi provides basic information necessary for differential diagnosis and for determination of the occurrence of malignant change in preexisting nevi.