Intracranial dermoid cyst - ruptured

Case contributed by Mostafa Elfeky
Diagnosis almost certain


Seizures and intractable headaches.

Patient Data

Age: 35 years
Gender: Male

A sizable right paramidline complex cystic lesion is noted measuring 4 x 3.7 x 5.6 cm in AP, SS and CC dimensions. It is mainly located at the suprasellar and right parasellar regions, extending to the right temporal and frontal fossae. It shows heterogeneous high signal on T1 and T2 with a heterogeneous mixed signal on FLAIR. No diffusion restriction. No enhancement could be appreciated.

Evidence of rupture with fat signal droplets seen at the body of both lateral ventricles and at the cortical sulci, notably at the right posterior parietal region and at the right temporal fossa.

It exerts a mass effect in the form of a midline shift by 0.8 cm. It is compressing the medial right temporal lobe and inferior aspect of the right frontal lobe. It is compressing the third ventricle and the frontal horns of both lateral ventricles. It is displacing right MCA posteriorly and both ACAs to the left side.

Case Discussion

Features are impressive of a right paramidline intracranial dermoid cyst, complicated by rupture into the ventricular system and subarachnoid space. Imaging findings are characteristically the high signal intensity on T1 and T2, no diffusion restriction or enhancement. Most of the intracranial dermoid cysts present with rupture that results in brisk arachnoiditis explaining the acute onset of symptoms.

Diffusion shows no restriction excluding the possibility of an epidermoid cyst. It also shows blooming artifact (could be mistaken for a hemosiderin-containing lesion).

Differential diagnoses for fat-containing intracranial lesions are epidermoid cyst, craniopharyngioma, intracranial teratoma and intracranial lipoma.

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