NF1 and von Hippel-Lindau disease: Approximately 85% of NETs are sporadic and the remainder occur as part of familial cancer syndromes including multiple endocrine neoplasia-type 1 (MEN1), von Hippel-Lindau disease (VHL), von Recklinghausen's disease (neurofibromatosis 1, NF1), and tuberous sclerosis (TS) [3–5].