Pituitary Abscess with Panhypopituitarism Showing T1 Signal Hyperintensity of the Marginal Pituitary Area: A Non-invasive Differential Diagnosis of Pituitary Abscess and Pituitary Apoplexy

Abstract

Abstract

Unusual Presentation of Recurrent Pituitary Abscess

“…T1 signal hyperintensity is observed mainly at the periphery as a hyperintense rim, like that in brain abscess. This appearance may correspond to paramagnetic T1 shortening due to the presence of free radicals, the products of actively phagocytosing macrophages in the capsule wall 1,16 . High T1 signal intensity noted in the centre of the lesion may reflect a small amount of blood products in the proteinaceous purulent contents of the abscess 1,16 .…”

“…Pituitary abscess may show variable signal intensity on T1-weighted images. The signal intensity of this lesion may be modified by its protein content or the presence of haemorrhage 1,4,12,12,16 . A hyperintense signal may be noted either at the periphery or within the abscess.…”

“…It was also reported that pituitary apoplexy occasionally demonstrates ring enhancement after gadolinium injection 1 . Pituitary abscess has also been reported to show high signal intensity on diffusion-weighted imaging (DWI) 1,17,18 . On the other hand, pituitary apoplexy also demonstrates high signal intensity on DWI due to ischemic injury or deposit of blood derived substances.…”

“…However, the clinical diagnosis is difficult because there are no clinical symptoms typical for pituitary abscess. It is frequently indistinguishable clinically or with neuroimaging from other pituitary lesions [1][2][3][4][5] . Since the first description by Simmonds in 1914, more than 210 cases of pituitary abscesses have been reported in the medical literature, mostly as isolated case reports [6][7][8][9][10][11] .…”

T1 Hyperintense Cystic Lesion – an Epidermoid or an Abscess?

“…Our case shows that an abscess situated in the same location can have identical signal characteristics. T1 hyperintensity in an abscess has been reported [10][11][12]. The capsule of a brain abscess may be hyperintense due to T1 shortening resulting from the presence of free radicals that accumulate as products of phagocytosis by macrophages [11].…”