MAP2K1-Mutated Melanocytic Neoplasms With a SPARK-Like Morphology
Michele Donati, Daniel Nosek, Pia Waldenbäck, Petr Martínek, Björn‐Anders Jonsson, Petra Galgonkova, Marcela Hawawrehova, Petra Berouskova, Liubov Kastnerova, Paolo Persichetti, Anna Crescenzi, Michal Michal, Dmitry V. Kazakov
Abstract
ABSTRACT: Specific alterations involving MAPK genes (MAP3K8 fusions, MAP3K3 fusions) have been recently detected in a subgroup of spitzoid neoplasms that seem to constitute a distinctive clinicopathologic group, occur mostly in younger patients (median age 18 years) and present with atypical histologic features associated with frequent homozygous deletion of CDKN2A, qualifying a high proportion of them as Spitz melanoma (malignant Spitz tumor). Apart from lesions with spitzoid morphology harboring MAP3K8 or MAP3K3 fusion, a single case with MAP2K1 deletion has been identified. The authors report herein 4 melanocytic lesions with a MAP2K1 mutation, all showing similar microscopic appearances, including spitzoid cytology and dysplastic architectural features, resembling so-called SPARK nevus, suggesting that these lesions may represent another distinctive group.