[The dysplastic nevus].

Dysplastic nevus is a controversial category of melanocytic nevi. Formerly regarded as "formal histogenetic precursors of melanoma" or intermediate lesions in the progression of "common acquired nevi" to melanoma, dysplastic nevi are now considered to be benign melanocytic nevi that may simulate melanoma histopathologically. The dysplastic nevus is a very common type of melanocytic nevus. It is limited to the epidermis and papillary dermis, with the epidermal component extending beyond the dermal one; composed mostly of melanocytes with small, monomorphous nuclei; and also known as Clark's nevus. Based on an abundance of histopathologic criteria, distinction from melanoma is usually possible even in the case of some unsual findings. The term "dysplasia," originally introduced to signify diagnostic uncertainty, remains problematic because it suggests a distinct biologic quality. When employing the term "dysplastic nevus," it should be made clear whether one is referring to the common type of nevus named after Clark or whether one is trying to signify diagnostic uncertainty.