The Classification of Pituitary Tumors: An Update

The classification of pituitary tumors includes the large group of common pituitary adenomas, the rare pituitary carcinoma, craniopharyngiomas, and various other primary and secondary neoplasms that arise in the region of the sella turcica. In addition, there is a group of tumorlike lesions that can mimic pituitary tumors, including cysts, inflammatory conditions, and hyperplasias. The understanding of pituitary adenoma cyto-differentiation has been greatly enhanced by the identification of transcription factors that regulate cell differentiation in this gland; these factors provide novel tools for tumor classification and diagnosis. The pathologist plays an important role in identifying the morphologic features of pituitary lesions to ensure appropriate classification and clinico-pathological correlations that will determine patient management.