Pigmented nevi. Induced changes in the junctional component.

The pigmented nevus represents a potentially more dynamic lesion than has been indicated by most published studies. New nevus cell clusters frequently appear in the epidermis over the residual portion of a nevus that remains after partial surgical excision. Even in relatively inactive nevi in adults, new junctional nevus cells may be induced by surgical trauma. This stimulated growth usually regresses by the time one year or more has elapsed. The growth of nevus cells is probably comparable to that induced in other cells by traumatic injury. There is no evidence to suggest that it is related to the development of melanoma in pigmented nevi.