To date, seven CDKN1B germline mutations have been identified in MEN4 patients primarily associated with MEN1-related lesions, including parathyroid and pituitary tumors, but the presence of other malignancies such as renal angiomyolipoma, papillary thyroid carcinoma and pancreatic masses has also been reported [8], [9], [14], [16], [17]. Here, CDKN1B is linked to pituitary tumor.