WDSM represents a variant with molecular heterogeneity and a highly variable tumor burden, despite its unique morphologic, immunophenotypic, and clinical features: mast cells are characterized by a distinct well-differentiated morphology, usually lack CD2 and CD25 but show CD30 expression, and low frequency of the typical KIT D816V mutation and other exon 17 KIT mutations [36]. This evidence concerns the gene TNFRSF8 and neoplasm.