Dysplastic Nevi
Since their original characterization by Clark and colleagues in 1978,[1] dysplastic nevi have posed a management dilemma, given their position in the gray area between benign melanocytic nevi and malignant melanoma. Even their histologic typing is the subject of debate, with some pathologists preferring to avoid the common grading system of mild, moderate, or severe atypia.[2]
Dysplastic nevi are benign melanocytic tumors containing clonal populations of hyperproliferative melanocytes. Strictly speaking, dysplastic nevus is a histologic diagnosis, characterized by architectural disorder and cytologic atypia. "Atypical nevus" is the clinical correlate, typified by the classic ABCD criteria of asymmetry, border irregularity, color variegation, and size > 6 mm.
Dysplastic nevi are common in people of Northern European descent, with prevalence estimates ranging from 7% to 24%.[3] Although dysplastic nevi may progress to cutaneous melanoma, most lack the genetic mutations characteristic of cutaneous melanoma, such as CDKN2A, TP53, NF1, RAC1, and PTEN.[4]
Malignant transformation of dysplastic nevus to cutaneous melanoma is rare, with one study estimating a dysplastic nevus-to-melanoma transformation rate of 1 in 30,089 nevi in males and 1 in 39,809 nevi in females.[5]Nevertheless, patients with multiple dysplastic nevi and/or a family history of dysplastic nevus syndrome have a greater risk of developing cutaneous melanoma, with relative risk estimates ranging from 1.6 for individuals with one dysplastic nevus to 10.5 for those with five or more.
