Precursor lesions of melanoma: do they exist?

The question of whether definite precursors to melanoma exist is answered in the affirmative. Three cutaneous lesions likely to be such precursors are described and discussed as to their clinical and histologic appearance and incidence. Additionally, a type of conjunctival melanosis that has been associated with malignant melanoma of the conjunctiva is discussed and an attempt is made to define it; a proposed classification of this entity is reviewed. Basic approaches to management and analysis of precursor lesions are elaborated.