NF1 and neoplasm: Neurofibromatosis type 1 (NF1) is a common cancer predisposition syndrome, affecting approximately 1 in 3,000 individuals worldwide.1 All individuals with NF1 are born with a germline mutation in one copy of their two NF1 tumor suppressor genes, but develop benign tumors following somatic inactivation of the remaining NF1 allele.2 Although benign tumors predominate in children with NF1, adults with NF1 are at risk for malignancy, most commonly malignant peripheral nerve sheath tumors (MPNSTs).