In 2001, a good review of Speckled Lentiginous Nevi appeared in the Archives of Dermatology. It's hypothesis: "These 10 cases, along with the arguments outlined in the article, provide strong support for the hypothesis that speckled lentiginous nevi are a subtype of congenital melanocytic nevus."
This article is now available free full-text online. These lesions should be followed and biopsies performed if there are any worrisome changes.