Supra sellar rule 3 :Supra sellar hot spot

If you elicited a fatty lesion in the supra sellar area, you will see it with hypo dense appearance similar to that of the fat in CT imaging which gives CT density till 100 Hounce field units by minus .While by MRI, it will give a hyper intense signal by T1 and intermediate intense by T2.Heamorrhagic lesions in T1 MRI gives also hyper intensity.

So, first we localize the lesion in the supra sellar area, then we characterize it as a hyper intense focal lesion in MRI T1, then we must finally mention the differential diagnosis available for this characterization which are the following:

-Ectopic posterior pituitary(fatty lesion):

Here, simply look at sella and see if the posterior pituitary is located in its normal position or not, if it is not located think about ectopic site, if it is seen, look for other differential.

-Craniopharyngioma(small fatty lesion).

-Lipoma and dermoid cysts(fatty lesions), and these lesions can be differentiated easly by their non enhancement pattern.

-Teratoma of tuber synerium.

Summary

-Finding is a hyper intense lesion seen in the supra sellar area in MRI T1 imaging.

-Look to the pituitary gland in its normal position inside sella, and be sure that its posterior lobe is present or not, if not present, so the hyper intense supra sellar lesion is ectopic posterior pituitary lobe. If seen in the sella, so think about other differential as the following:

-In contrast enhanced MRI T1 with fat suppression, if it is enhanced, consider it craniopharyngioma.

If not enhanced, look to the place of the lesion, if it is centrally located, think about dermoid cyst.If it is situated at the tuber synerium, so it will be teratoma.If it is present elsewhere in supra sellar area, it could be a lipoma.