Hypophysitis or PitNET?

Hypophysitis is defined as an inflammatory pituitary disease usually leading to pituitary deficiencies. It can be primary, the most frequent etiology being autoimmune or secondary as part of a systemic disease, such as sarcoidosis, histiocytosis, Crohn’s disease, or granulomatosis with polyangiitis for instance. Lymphocytic hypophysitis is the most common primary hypophysitis and affects preferentially young women, particularly during pregnancy. IgG4 hypophysitis could account for 30% of all cases of primary hypophysitis. Infundibuloneurohypophysitis represents the most frequent etiology of isolated AVP deficit. Hypophysitis related to immunomodulatory drugs may have low visible manifestation. Xanthomatous hypophysitis is today considered as secondary to a RCC rupture. The differential diagnosis of hypophysitis is with PitNET. In hypophysitis, the sella is not enlarged, the pituitary stalk is thickened but not deviated, the normal pituitary tissue is not visible and FLAIR demonstrates a hypersignal.