Ectopic Posterior Pituitary Lobe and Periventricular Heterotopia: Cerebral Malformations with the Same Underlying Mechanism?
L. Anne Mitchella,e,g,
Paul Q. Thomasd,
Margaret R. Zacharinb and
Ingrid E. Schefferc,f,h
a Department of Radiology, Royal Children’s Hospital, Melbourne, Australia
b Department of Endocrinology and Diabetes, Royal Children’s Hospital, Melbourne, Australia
c Department of Neurology, Royal Children’s Hospital, Melbourne, Australia
d The Murdoch Children’s Research Institute, Royal Children’s Hospital, Melbourne, Australia
e Department of Radiology, Austin & Repatriation Medical Centre, Melbourne, Australia
f Department of Neurology, Austin & Repatriation Medical Centre, Melbourne, Australia
g Department of Radiology, University of Melbourne, Melbourne, Australia
h Department of Medicine, University of Melbourne, Melbourne, Australia
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FIG 1. Images from case 1, with typical findings of ectopic posterior pituitary lobe.
A, Unenhanced midline sagittal spin-echo T1-weighted image (625/13/4) shows hyperintensity corresponding to ectopic posterior pituitary lobe at the median eminence (short arrow). The pituitary gland and sella turcica are small, with a thin infundibulum (long arrow).
B, Coronal T1-weighted spoiled gradient-recalled image shows a small heterotopic nodule, isointense to gray matter, above the left trigone (arrow).
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FIG 2. Images from case 2.
A, Unenhanced midline sagittal spin-echo T1-weighted image (625/13/4) shows a small hyperintensity at the median eminence typical of ectopic posterior pituitary lobe, with a second small hyperintensity extending downward into the upper infundibulum (arrows). The infundibulum is thinned, with a small pituitary gland and sella turcica. The splenium of the corpus callosum is small.
B, Axial fast spin-echo T2-weighted images (5200/102/3) show small heterotopic nodules isointense to gray matter, above the frontal horns (arrowheads).
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FIG 3. Image from case 3. Unenhanced midline sagittal view spin-echo T1-weighted image (625/13/4) shows hyperintensity at the median eminence, typical for ectopic posterior pituitary lobe (short arrow). A small hyperintense focus can also be seen lying posterosuperiorly on the superior aspect of the small pituitary gland (curved arrow), which probably also represents ectopic pituitary tissue. The sella has an abnormal morphology, with a sloping anterior wall. It contains a thin layer of soft tissue lining the floor of the dysplastic anterior sella and more recognizable pituitary tissue in the base of the sella. The infundibulum is difficult to definitely identify because it is markedly thinned but may lie more anteriorly than usual (long arrow).
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FIG 4. Images from case 4.
A, Unenhanced midline sagittal spin-echo T1-weighted image (625/13/4) shows two brightly hyperintense foci: one involving the mammillary bodies and the other in the interpeduncular cistern (black arrowheads). There is also a smaller less hyperintense focus located at the expected site of the median eminence, suggestive of ectopic posterior pituitary lobe (white arrow). The pituitary gland and sella are small, with a suggestion of a tiny posteriorly angled infundibulum.
B, Unenhanced sagittal spin-echo T1-weighted image (650/9/2) with fat suppression, obtained at the same position as the image shown in A, shows suppression of the two larger more posteriorly located hyperintensities (black arrowheads), indicating that these represent lipomas. The smaller anterior hyperintensity of ectopic posterior pituitary lobe does not suppress (white arrow). A little flow-related artifact is seen in the floor of the third ventricle between the median eminence and the mammillary bodies.
C, Contrast-enhanced sagittal spin-echo T1-weighted image (650/9/2) with fat suppression shows enhancement of the median eminence, confirming that the anterior hyperintensity lies at a typical location for ectopic posterior pituitary lobe (short arrow). Enhancement of the infundibulum can also be seen (long arrow). The two lipomas remain suppressed, with no enhancement (arrowheads).
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