Pituitary in Systemic Diseases

Abstract

Systemic diseases represent a group of diseases of unknown origin that affect the body as a whole. Therefore, they are known to develop in multiple organs and may sometimes involve the sellar region. There, they can be located within the anterior pituitary lobe, resulting in hypophysitis and hypopituitarism; in the stalk or the infundibulum, being a source of diabetes insipidus and sometimes mimicking a suprasellar tumor; a combination thereof; or in the parasellar meninges, cavernous sinus, skull base, or neighboring brain. Two opposite situations may lead to the diagnosis of a systemic disease lesion in the sellar region: first, the diagnosis is straightforward when the underlying systemic disease is already known and MRI depicts a lesion there; second, which is more delicate, when a lesion is depicted in the sellar region and the radiologist has to evoke the diagnosis of a specific systemic disease. Clues hopefully exist, and together with the knowledge of particular patterns suggestive of each disease, make the diagnosis feasible or, at least, help the radiologist to suggest it. In general, in patients with a sellar/suprasellar mass and unusual clinical presentation such as diabetes insipidus or associated neurological deterioration, granulomatous lesions should be carefully considered in differential diagnosis. Systemic diseases are numerous and encompass various autoimmune diseases, connective tissue diseases, granulomatosis, and vasculitis. Autoimmune hypophysitis have been detailed in Chap. 40. Here, granulomatous hypophysitis and other lesions located in the sellar region in the setting of nonautoimmune systemic diseases, such as sarcoidosis, histiocytosis, or Wegener granulomatosis, are illustrated.