Overview and clinical application in the 2017 World Health Organization classification of pituitary tumors

The fourth edition of the World Health Organization classification of tumors of the pituitary gland was promulgated in 2017. The revised classification emphasized the classification of pituitary tumors based on the origin of cell differentiation. The term of atypical pituitary adenoma was no longer recommended, and morphological parameters should be considered as an important prognostic feature in aggressive adenomas. Genetic profile and susceptibility of pituitary tumors were updated. And an additional novel aspect was the definition of some of the nonneuroendocrine tumors. The revised classification will help the pathologists to make better diagnosis, and contribute to improve our understanding of clinical outcomes for those patients. (Chin J Endocrinol Metab, 2018, 34: 623-626) Key words: Tumors of the pituitary gland; Pathological classification; Clinical application