[Hypophysitis : Types and differential diagnosis]

Inflammatory findings in the pituitary glands account for approximately 1 % of operations in the sellar region. Primary inflammation (e.g. lymphocytic and idiopathic granulomatous hypophysitis) have to be differentiated from secondary types (e.g. concomittant inflammation with Rathke's cleft cysts, craniopharyngiomas and germinomas) and involvement of the pituitary in generalized inflammation (IgG4-related disease, sarcoidosis and septicopyemia). Langerhans cell histiocytosis also has to be considered for the differential diagnostics. Lymphocytic hypophysitis shows lymphocytic infiltrations of varying density, predominantly of the T‑cell type. Granulomatous hypophysitis has the features of sarcoidosis and can only be diagnosed by exclusion of generalized sarcoidosis. Secondary hypophysitis has a mixed cell infiltration, especially by histiocytic infiltration and predominantly originates from ruptures or bleeding from Rathke's cleft cysts. The frequently very sparse remnants of cyst epithelium should be confirmed by pankeratin immunostaining.