Are concurrent or subsequent malignant melanomas in the skin and eye related or coincidental?

Malignant melanomas sometimes occur simultaneously or subsequently in the skin and in the eye, multicentrically, not metastatically. The phenomenon is understandable in the B-K mole syndrome, in which multiple malignant melanomas are the rule. Otherwise simultaneous or subsequent malignant melanomas in one organ alone or in two disparate organs are rare and by change.