MAP2K1-mutated melanocytic tumors have reproducible histopathologic features and share similarities with melanocytic tumors with BRAF V600E mutations.

Melanocytic tumors with MAP2K1 in-frame deletion could represent another spectrum of melanocytic tumors with close genotypic-phenotypic correlation. They are largely characterized by a spectrum that encompasses desmoplastic Spitz nevus as shown in our series and Spitz and Clark nevus as shown by others. Evolutionary, they share many similarities with tumors with BRAF V600E mutations, suggesting they are better classified along the conventional pathway rather than the Spitz pathway despite the frequent spitzoid morphology.