NF1 and neurofibroma: NM-SC, rather than myelinating Schwann cells, are the key neoplastic element in neurofibroma despite both cell types harboring loss of NF1. Homozygosis loss of NF1 is the key factor leading to rapid cell growth and hyperplasia, but this alone is insufficient for formation of PN which may require cross-talk with other infiltrating cell types [28].