Melanoma arising de novo over a 16-month period.

Choroidal melanoma is widely regarded as a slow-growing tumor. We report herein the first documented case, to our knowledge, of a choroidal melanoma present in an eye in which examination 16 months earlier disclosed no tumor. On gross examination following enucleation, the largest tumor diameter at the base was 19 mm and the height was 11 mm. The implications as to the growth rate and the precursor lesions of choroidal melanomas are discussed.