Pituitary Disorders

Hypopituitarism usually results from a deficiency of anterior pituitary hormones or, rarely, from tissue resistance to these hormones. Deficiency may be from primary pituitary disease, pituitary stalk disorders, hypothalamic disease, or an extrasellar disorder impinging on, or infiltrating, the hypothalamic-pituitary unit. Primary pituitary disease results from the loss of anterior pituitary cells and may be congenital or acquired. Common causes are pituitary tumors and their surgical or radiotherapeutic ablation. Infrequent causes include pituitary infarction (eg, postpartum pituitary necrosis, also known as Sheehan syndrome), pituitary apoplexy, lymphocytic hypophysitis, infiltrative diseases (eg, hemochromatosis), and metastatic disease (eg, from breast or lung).

Diseases of the Pituitary Gland

A wide variety of distinct pathological conditions may affect the pituitary, causing hormonal dysfunction and/or compression of surrounding structures. This chapter describes and illustrates the main pituitary lesions. Pituitary adenomas represent 10% to 20% of intracranial neoplasms in neurosurgical series. Their classifications are based on multiple factors, including histology and immunohistochemistry, ultrastructure and endocrine activity. Pituitary carcinomas are extremely rare. Pituitary hyperplasia is a rare cause of pituitary hyperfunction. Inflammatory (lymphocytic hypophysitis, granulomatous hypophysitis) and vascular (pituitary infarction, pituitary apoplexy, Sheehan syndrome) lesions can cause hypopituitarism. Craniopharyngiomas are the second most common neoplasm of the sellar region, following pituitary adenomas, and the most common suprasellar neoplasm in children.