1983 NIH Consensus Development Conference: "Dysplastic nevi are acquired pigmented lesions of the skin whose clinical and histologic definitions are evolving. They differ from common, acquired pigmented nevi in several respects and some cannot be clinically distinguished from melanoma. . . . Typical dysplastic nevi measure 5 to 12 mm in diameter and tend to be larger than common nevi. Dysplastic nevi have both macular and papular components and have borders that usually are irregular and frequently are ill-defined. Their color is variegated, ranging from tan to dark brown on a pink background."

1992 NIH Consensus Development Conference: "Atypical moles (dysplastic nevi) are acquired pigmented lesions of the skin whose clinical and histological appearances are different from those of typical common moles (common nevi). . . . Atypical moles vary in size and are often larger than common moles. Atypical moles have macular and/or papular components and have borders that usually are irregular and frequently are ill-defined. Their color is variegated, ranging from tan to dark brown, often on a pink background."

Critique: The Panels of both Consensus Development Conferences "bought in" completely to Clark's concept that DN are different, clinically and histopathologically, from common acquired nevi (CAN) and that they are similar clinically, if not identical, to melanoma.11–14 Both perceptions are incorrect and are the basis for the wrong notion of Kopf and co-workers that the ABCDs (Asymmetry, Border irregularity, Color variability, and Diameter greater than 6.0 mm) apply equally to clinical diagnosis of DN and of melanoma.15–16 In actuality, DN are the most common acquired nevus, and they usually are distinguishable readily from melanomas clinically, a not surprising assertion when one considers how very different they are histopathologically from melanomas. Neither the Consensus Development Conference of 1983 nor of 1992 addressed the matter of criteria for clinical diagnosis of "common acquired nevus," the reason being that there is no single kind of common acquired nevus, but rather there are several different types of common acquired nevi, e.g., Unna's, Spitz's, and Clark's.