NGF and neoplasm: In this context, neurofibromin‐deficient Schwann cells (Nf1 −/−) secrete chemotactic factors (Kit ligand) to stimulate the migration of haploinsufficient mast cells (Nf1 +/−), which in turn can locally secrete neural growth factor (NGF) and vascular endothelial growth factor (VEGF) in the tumor microenvironment.33 Ultimately, this indicates the potential implication of the interaction of Schwann cells and mast cells and inflammation in the pathogenesis of neurofibromas.