Suprasellar lipoma

Case contributed by A.Prof Frank Gaillard

Presentation

Vague headaches and possible visual disturbances.

Patient Data

Age: 20 years
Gender: Female
CT

CT brain

A 7 mm fat containing suprasellar mass is demonstrated. There is no significant mass effect on adjacent structures.  Elsewhere are ventricles and sulci are within normal limits. No further acute intracranial pathology, including haemorrhage seen. No suspicious bone lesions.

MRI

MRI brain

Suprasellar mass present which lies posterior to the infundibulum, likely centred in the tuber cinereum measures 4.5 x 7 x 5 (AP X CC x RL) demonstrates homogenous T1 and T2/FLAIR hyperintensity, demonstrates chemical shift artifact and saturates out on fat saturation consistent with fatty lesion. Small nodule of non fatty component is present within it measuring less than 1 mm, possibly demonstrating enhancement. 

The optic nerves and chiasm do not contact the lesion. No evidence of mass effect on the infundibulum. The midline structures are otherwise normal. 

MRI

Annotated images

Establishing a lesion is composed of fatty material can be achieved in a number of ways:

  1. Hounsfield measurement on CT (negative, typically around -90 to -110 HU)
  2. Fat saturation results in fatty tissue losing all signal and appearing black (yellow arrows). 
  3. Chemical shift artefact on MRI T2 weighted image demonstrate chemical shift artefact around the lipoma in the frequency encoding direction (superior-inferior). Note how there is signal loss superiorly (black arrows) and hyperintensity inferiorly (white arrows). This is the result of inaccurate spatial encoding, resulting in the lipoma being incorrectly placed inferior to its actual location

Case Discussion

This case demonstrates what is most likely a small suprasellar lipoma. The differential of a dermoid cyst is difficult to categorically exclude however the completely homogeneous fatty signal intensity (which completely attenuates on fat suppressed sequence), absence of evidence of previous rupture and the mere fact that they are less common than lipomas makes it far less likely. 

PlayAdd to Share

Case information

rID: 17922
Case created: 25th May 2012
Last edited: 28th Jun 2017
Inclusion in quiz mode: Included

Updating… Please wait.
Loadinganimation

Alert accept

Error Unable to process the form. Check for errors and try again.

Alert accept Thank you for updating your details.