Pituitary MRI Features in Acromegaly due to Ectopic GHRH Secretion from a Neuroendocrine Tumor: Analysis of 30 cases

Ectopic acromegaly is a consequence of rare neuroendocrine tumors (NET) that secrete growth hormone releasing hormone (GHRH). This abnormal GHRH secretion drives growth hormone (GH) and insulin-like growth factor 1 (IGF-1) excess, with a clinical presentation similar to classical pituitary acromegaly. Identifying the underlying cause for the GH hypersecretion in the setting of ectopic GHRH excess is, however, essential for proper management both of acromegaly and the NET. Owing to its rarity, the imaging characteristics of the pituitary in ectopic acromegaly have not been analyzed in depth in large series.Characterize pituitary magnetic resonance imaging (MRI) features at baseline and after NET treatment in patients with ectopic acromegaly.Multicenter, international, retrospective.Tertiary referral pituitary centers.30 ectopic acromegaly patients due to GHRH hypersecretion.None.MRI characteristics of pituitary gland, particularly T2-weighted signal.In 30 patients with ectopic GHRH-induced acromegaly, we found that most patients had hyperplastic pituitaries. Hyperplasia was usually moderate but was occasionally subtle, with only small volume increases compared to normal ranges for age and sex. T2-weighted signal was hypointense in most patients, especially in those with hyperplastic pituitaries. After treatment of the NET, pituitary size diminished and T2-weighted signal tended to normalize.This comprehensive study of pituitary MRI characteristics in ectopic acromegaly underlines the utility of performing T2-weighted sequences in the MRI evaluation of patients with acromegaly as an additional tool that can help to establish the correct diagnosis.