In the last decade, significant progress has been made in our understanding of the genetic
alterations in melanocytic tumors. The most exciting finding is the discovery of oncogenic
BRAF mutations in both malignant melanoma and melanocytic nevi. This finding indicates
that activation of the mitogen-activated protein kinase pathway may be a critical initiating
step of melanocytic neoplasia, and that the fundamental difference between melanoma and
nevi may lie in the inhibitory machinery for this oncogenic signaling. In addition, different …