In the fifth patient, an obvious abnormality was found at surgery at the site identified on Met-PET, but histology was not confirmatory of a prolactinoma; however, this likely reflected a small tumor with total resection as evidenced by restoration and maintenance of normal serum prolactin following surgery—analogous to surgical/histological findings in some corticotroph tumors. Here, PRL is linked to prolactin-producing pituitary gland adenoma.