Atypical Nevi, Clark and Dysplastic Nevi
In 1978 Wallace Clark, a pathologist, described a pigmented lesion that was familial and associated with a family history of melanoma. He called this lesion a dysplastic nevus. These lesions are now referred to as atypical moles (AMs) or Clark nevi. The mode of inheritance is probably autosomal dominant.
The criteria for the syndrome of familial atypical mole and melanoma (FAMM) were established by the National Institutes of Health. They are (1) the occurrence of malignant melanoma in 1 or more first- or second-degree relatives; (2) the presence of numerous (often >50) melanocytic nevi, some of which are clinically atypical; and (3) many of the associated nevi show certain histologic features.
It is now known that AN also occur in individuals sporadically without a family history of melanoma. The clinical and histologic criterion of these lesions is still evolving.