Fig. 1. (A) Sagittal MRI scan of the head of a normal child showing the corpus callosum (cc), the optic chiasm (oc), the anterior pituitary (ap), the pituitary stalk (ps) and posterior pituitary (pp) in the normal sella turcica. Note the well-formed corpus callosum and the optic chiasm and the posterior pituitary which appears as a bright fossa within the sella turcica. (B) Sagittal MRI scan of sibling 1 with a homozygous R160C mutation in HESX1. Note that the splenium of the corpus callosum is more hypoplastic than the rest of the structure and that the sella turcica is shallow as compared with the MRI scan of sibling 2 (C). The posterior pituitary (pp) appears to be partially descended. (C) Sagittal MRI scan of sibling 2 with a homozygous R160C mutation in HESX1. The corpus callosum (cc) is severely hypoplastic, as is the optic chiasm (oc) and the anterior pituitary (ap) located in a well-formed but empty sella turcica. Note the ectopic posterior pituitary (pp) and the lack of a visible pituitary stalk. (D) Sagittal MRI of a patient with S170L mutation in HESX1. Note the atrophic posterior pituitary (pp) that has not descended completely into the fossa and an anterior pituitary (ap) gland that is hypoplastic and does not enhance well. The pituitary stalk is thin, but the optic chiasm (oc) is normal as is the corpus callosum (cc).
