Among the immunohistochemical stains used for diagnosis is variable expression demonstrating S100 and/or SOX10, these markers may be decreased or absent compared to other tumor types such as schwannomas, also demonstrate loss of neurofibromin expression and trimethylation of H3K27, the latter, is a key epigenetic marker that is lost in MPNST and has a relatively high specificity for diagnosis, however, close mimickers such as melanoma may also demonstrate loss [13,14]. The gene discussed is NF1; the disease is neoplasm.