Endocrinological and MRI features of pituitary adenomas with marked xanthogranulomatous reaction.

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

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

Results: 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.

Conclusions: 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.