Laura Flisnik, MD

A 46-year-old male presents with headache.


On brain MRI, well-circumscribed fat containing lesion centered in the right suprasellar space with mild mass effect on the right optic tract and midbrain most characteristic for an unruptured dermoid cyst.

Dermoid cysts are benign epithelial cysts that contain dermal elements. They characteristically present as midline unilocular cystic fat containing masses. Most commonly, they are located in the suprasellar space or posterior fossa. Extracranial sites include the orbit and spine.

On CT, dermoid cysts appear as well-circumscribed hypodense structures with negative Hounsfield units occasionally associated with capsular/peripheral calcifications. Rarely, dermoids can present as hyperattentuating lesions referred to as “dense dermoids”. 

On MRI, dermoid cysts demonstrate T1 shortening with prolongation on T2 weighted sequences and loss of signal with fat-suppression technique, which is confirmatory for the diagnosis. There can be mild capsular enhancement on postcontrast imaging. When dermoid cysts rupture, fat-fluid levels within the basal cisterns can be seen, as well as fatty deposits throughout subarachnoid space.

Once again, this can be confirmed on fat-suppression sequences. Rupture can lead to chemical meningitis as evidenced by diffuse leptomeningeal enhancement best identified on postcontrast fluid attenuating imaging. Other differential considerations include epidermoid cyst, craniopharngioma, and lipoma.

Dermoid cysts most commonly affect men in their second to third decade. Patients typically present with headache or seizure. Less commonly, hypopituitarism or visual symptoms if the lesion is suprasellar in location. Large cysts can cause obstructive hydrocephalus.

Dermoids are slow growing benign tumors. There is a small potential for malignant degeneration to squamous cell cancer. Due to the risk or rupture with increased tumor size, dermoids are treated with complete surgical excision to prevent the significant morbidity and mortality that follows cyst rupture. There is a small chance of tumor recurrence with residual capsule.

1. Liu JK, et al. Ruptured intracranial dermoid cysts: clinical, radiographic and surgical features. 

2. Orakcioglu B, et al. Intracranial dermoid cysts: variations of radiological and clinical features. 

Author | Laura Flisnik, MD

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