GNAS and pituitary gland adenoma: It is of interest that GNAS mutations were frequently detected in benign tumors such as colorectal villous adenoma (83%) [11], appendiceal low- grade mucinous neoplasm (50%) [21], pyloric gland adenoma (63%) [12], inflammatory type hepatocellular adenoma (5%)[22] and pituitary adenoma (40%)[23].