Partial ectopic posterior pituitary

Abstract

Ectopic posterior pituitary is one of the leading causes of pituitary dwarfism related to a growth hormone deficiency. It can be either isolated or associated to other abnormalities, the most widely known being the pituitary stalk interruption syndrome [1]. Although it is a rare entity, partial ectopy consists of the coexistence of both an orthotopic and an ectopic posterior pituitary gland [2,3] (Figure 1A). It appears as a T1 hyperintensity or bright spot at the posterior sellae, consistent with the normally expected neurohypophysis [4]. A second midline bright spot located in the infundibulum (Figure 1B), or above the optic chiasm or at the floor of the third ventricle is considered the ectopic posterior pituitary gland. It features high T1 signal intensity with and without fat suppression, making it easy to distinguish from a lipoma or a supra sellar dermoid with lipid content. Contrast enhancement is similar to the normal pituitary parenchyma (Figure 1C).