Histological features of pituitary adenomas and sellar region masses

Most pituitary region masses are pituitary adenomas; however, when other sellar region masses are encountered by clinicians or pathologists, the differential diagnosis can be broad. This review will focus on updates for pituitary adenomas, as well as briefly discuss some of these other entities: Rathke cleft cyst, hypophysitis, craniopharyngioma, pituicytoma, and spindle cell oncocytoma.

The use of new immunohistochemical (IHC) tools for assessing transcription factors, pituitary transcription factor-1, steroidogenic factor-1, and the not-yet-widely available Tpit IHC have provided insights into origin particularly of clinically silent and even hormone-negative pituitary adenomas. IHC for keratins coupled with use of E-cadherin IHC can serve to easily identify sparsely granulated growth hormone adenomas that behave more aggressively and may not respond well to some therapies. Thyroid transcription factor-1 IHC has shown common embryological lineage of pituicytoma, spindle cell oncocytoma, and granular cell tumor of neurohypophysis.

IHC supplements classification of pituitary adenoma subtypes for clinicians and can confirm diagnosis of nonpituitary adenoma sellar region masses.