Ruptured intracranial dermoid

Case contributed by A.Prof Frank Gaillard


Sudden onset headache. History of prior surgery overseas.

Patient Data

Age: 40 years
Gender: Female

CT brain

Evidence of previous right frontal craniotomy. There is a partial fat density, partial soft tissue density (fat-soft tissue level) ovoid, lobulated mass centered within the suprasellar cistern, the fatty component measuring 2.5cm (trans) x 3cm (ap) x 2.2cm (cc). The mass, predominantly its fatty component, extends through a defect in the anteroinferior sella turcica/jugum into and largely filling the left sphenoid sinus and left posterior ethmoidal air cells (a probable solid component in the left lateral wall of the sphenoid sinus) into left superior ethmoidal recess, thence along the posterosuperior nasal septum, which appears slightly fragmented. A fistulous tract to skin is not seen. No orbital extension seen.

A contiguous soft tissue density posterior component to the mass also resides within the suprasellar cistern, centered slightly to the right of the midline, effacing the floor of the third ventricle and with likely optic chiasm mass effect, poorly seen on these images.

Multiple locules of fat attenuation are seen within the subarachnoid space, within the Sylvian fissures and interhemispheric fissure. There is some subtle fat attenuation within the region of the left choroid plexus and another speck along the septum pellucidum anterosuperiorly related to the calcified pineal gland. No other hypoattenuation is seen within the ventricles.

Wider window and ROI density measurment confirms fat density. 

MRI brain

A right frontal burrhole is noted. Fat packing of the left sphenoid sinus implies previous trans-sphenoidal surgery also.

A 27 x 20 x 17 mm suprasellar mass lies between the optic chiasm superiorly and pituitary infundibulum inferiorly, compressing both structures. On this supine study, the anti-dependent 1/3 of the mass shows high T1 signal and low signal with fat suppression. The dependent 2/3 shows high T2/FLAIR and intermediate T1 signal. A fluid level is demonstrated between the two components. No diffusion restriction, magnetic susceptibility or post-contrast enhancement is appreciated.

The mass is clearly separate from the pituitary gland, which has normal appearances other than non-identification of the normal posterior pituitary bright spot.
Multiple small foci of high T1 signal are evident in the subarachnoid space of the supratentorial brain, most numerous in the frontal regions (ie anti-dependent). There is no hydrocephalus.

Case Discussion

Findings are characteristic of a supra sellar dermoid cyst with ruputre into the subarachnoid space.

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Case information

rID: 23180
Published: 27th May 2013
Last edited: 14th Aug 2019
Inclusion in quiz mode: Included

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