MEN1 and neuroendocrine neoplasm: Neuroendocrine tumors also known as carcinoid tumors, most commonly occur sporadically but may be associated with hereditary syndromes such as multiple endocrine neoplasia type 1 (MEN1), neurofibromatosis type 1 (NF1), von Hippel–Lindau disease (VHL), and, more rarely, tuberous sclerosis.