These tumors are composed of neoplastic NF1-deficient Schwann lineage cells (Chen et al., 2019; DeClue et al., 1992; Kim et al., 1997; Le et al., 2011, 2009; Vogel et al., 1999; Zhu et al., 2002) and are classified as either cutaneous (discrete dermal) or plexiform (diffuse) neurofibromas. The gene discussed is NF1; the disease is plexiform neurofibroma.