The inflammatory lesion of the pituitary gland is unusual. A 33-year-old woman with headache, visual impairment, and menelipsis was admitted to the Second Xiangya Hospital, Central South University. The results of magnetic resonance imaging (MRI) for pituitary gland showed a sellar mass with iso-intensity on T1 weighted imaging and high signal on T2 weighted imaging. The homogeneous lesion was enhanced on contrast MRI. The pituitary stalk was thickened accompanied by the cavernous sinus invasion, which showed a "triangle" saddle occupation on the MRI coronal plane. An endocrinological examination revealed mild hypocortisolism. Th e patient was diagnosed as pituitary adenoma based on the MRI findings and endocrinological examination. Trans-sphenoidal surgery was performed. The intra-operative histological examination also suggested a pituitary adenoma. Th e histopathological examination showed accumulation of foamy cells and xanthomatous epithelioid cells, supporting the diagnosis of xanthomatous hypophysitis. Xanthomatous hypophysitis possesses certain MRI features. Th e most typical imaging features are the thickening of the pituitary stalk and the sign of "triangle" occupation on MRI coronal plane, which are very helpful to the correct diagnosis and optimal management.