CDKN2A and plexiform neurofibroma: Beert et al. (2011) demonstrated recurrent homozygous loss of the CDKN2A locus in 15/16 atypical neurofibromas; this finding supports the notion that atypical neurofibromas constitute intermediates between benign neurofibroma and MPNSTs and further suggests that CDKN2A loss is an early step in the progression of neurofibroma to MPNSTs [10].