MEN1 and parathyroid gland adenoma: According to MEN1 clinical practice guidelines, a patient is diagnosed with MEN1 by meeting one of the following three criterion: the manifestation of at least two primary MEN1-associated endocrine tumors (i.e., parathyroid adenoma, enteropancreatic tumor, and pituitary adenoma); the occurrence of one MEN1-associated tumor in a first degree relative of a patient with a clinical diagnosis of MEN1; and the detection of a germline MEN1 mutation in an individual, who may be asymptomatic without biochemical or radiological evidence of MEN1 [2].