The sellar region is a crowded and convergent crossroad of central and peripheral neural, meningeal, vascular, bone and soft tissue structures that predicts a wide diversity of primary or metastatic neoplasms arising from within any of these elements. The principle neoplasm of the sellar region is the anterior pituitary adenoma followed by neoplasms arising from the posterior pituitary. Knowledge of the surrounding anatomy predicts the types of symptoms that may arise from mass lesions in this region such as visual disturbances due to optic nerve compression; cranial neuropathies involving cranial nerves III, IV, V, and VI in the adjacent cavernous sinus; hypopituitarism or other more isolated endocrinopathies; and many others.

PITUITARY ADENOMAS

Benign pituitary adenomas account for the vast majority of tumors of the sellar region, and account for 10–15% of intracranial neoplasms. They are distinctly rare in children, only representing around 2% of all pituitary adenomas (Diamond, 2006; Kane et al., 1994). Pituitary adenomas were once classified along histochemical staining lines; however, this has been replaced by immunohistochemical profiling of adenomas and is an important adjunct to clinical care.

Pituitary adenomas cause clinical symptoms in one of two general ways: as a mass lesion or through abnormal hormone secretion. A large surgical series of pituitary adenomas indicates that the most common immunohistochemical subtypes of pituitary adenomas in decreasing frequency are prolactinomas, combined sparsely and densely granulated growth hormone–cell adenomas and null cell adenomas, followed by approximately equal frequencies of corticotroph cell adenomas and gonadotroph cell adenomas (Horvath et al., 2002).