Lymphocytic hypophysitis and other inflammatory conditions of the pituitary

Inflammatory lesions of the pituitary are far less common than pituitary adenomas. Although the most common of these, lymphocytic hypophysitis, is limited to the pituitary and pituitary stalk, many of the other lesions are usually part of a systemic process. Nonetheless, even these lesions, such as Langerhans’ cell histiocytosis (LCH) and sarcoidosis, sometimes present as part of disease limited to the central nervous system (CNS) and, rarely, present as isolated lesions of the hypothalamic/pituitary area. When lesions are located in the base of the hypothalamus or in the stalk, they commonly present with a combination of diabetes insipidus and hypopituitarism. In some cases, hypothalamic infiltration may be more widespread, affecting a variety of additional hypothalamic functions, such as satiety, sleep, and temperature regulation. These inflammatory lesions tend to be progressively destructive, resulting ultimately in fibrosis but the rate of progression is highly variable. When hypopituitarism or diabetes insipidus occur, they rarely recover even if the underlying process is directly treated. Thus, these lesions present more with endocrine hypofunction than with mass effects, although in early stages lymphocytic hypophysitis may well present with mass effects to the point where it can be confused with a pituitary adenoma.