Endocrinological and MRI features of pituitary adenomas with marked xanthogranulomatous reaction

The study aims to describe the endocrinological and magnetic resonance imaging (MRI) features of the rarely reported xanthogranulomas associated with pituitary adenoma.

Of 231 consecutive pituitary adenomas treated surgically, those with xanthogranulomatous reaction on histology were reviewed.

Five patients (2.2%) had an adenoma with marked xanthogranulomatous reaction. They were all nonfunctioning macroadenomas and presented with anterior pituitary insufficiencies. On MRI, all adenomas showed mixed signal intensities on T1- and T2-weighted images with heterogeneous gadolinium enhancement, reflecting their complex histological features: Cholesterol clefts typically showed T1 high- and T2 low-signal intensities. Preoperative diagnosis was difficult in a case predominantly featuring xanthogranuloma. Although none of them had episodes of pituitary apoplexy, hemosiderin deposits and cysts with xanthochromic-like fluid were observed in five and four cases, respectively.

Xanthogranulomatous reaction may develop in macroadenomas, probably triggered by hemorrhagic processes despite no apoplectic episodes. They typically exhibit complex mixed signal intensity on MRI, particularly T1 high- and T2 low-signal intensities, and patients present with pituitary dysfunction.