Intracranial dermoid cyst - ruptured

Case contributed by Antonio Rodrigues de Aguiar Neto
Diagnosis almost certain


Headache and seizures following head trauma.

Patient Data

Age: 30 years
Gender: Male

A non-contrast computed tomography (CT scan) revealed a heterogeneous low attenuation lesion centered in the left para sellar cistern (extra-axial fat-containing mass).

Additionally, there are multiply scattered locules of fat throughout the subarachnoid space and ventricular system.

Magnetic resonance imaging (MRI) shows a large mass in the left parasellar region, relating to the middle cerebral artery anteriorly and causing extrinsic compression on the left mesencephalon.

The lesion shows heterogeneous hyperintense signal on T1 and T2 weighted sequences, with loss of signal following fat suppression sequences.

Droplets of T1 hyperintense material are present throughout the subarachnoid space and ventricular system.

Case Discussion

Intracranial dermoid cysts are benign lesions of embryologic origin that represent less than 0,6 % of all primary intracranial tumors 1,2. Dermoid cysts contain ectodermal derivatives – hair follicles, sweat glands, and sebaceous glands 1,3.
Very rarely, the lesions may rupture and disseminate their intracystic contents into the subarachnoid space and ventricles 3.
Intracranial dermoid cyst can have mixed densities on CT scan with the fatty portion and fat droplets hypodense, and areas of calcification hyperdense ². These lesions usually show a hyperintense on T1-weighted images ³, with minimal to no enhancement after gadolinium administration, but it sometimes can appear more heterogeneous because of the presence of calcifications, hair, epithelial debris, and sebaceous secretion ².

The presence of disseminated lipid droplets in the subarachnoid cisterns or ventricles on CT or MRI is diagnostic for a ruptured dermoid cyst ².

Case courtesy

  • Erick Cavalcante, MD - PGY-3, Radiology Resident, Department of Radiology
  • Antonio Rodrigues de Aguiar Neto, MD - Radiologist, Department of Radiology
  • Hospital da Restauração – Recife, PE – Brazil

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