Ruptured intracranial dermoid cysts: Imaging at acute presentation and follow-up

Intracranial dermoid cysts are rare, benign congenital lesions that can rupture spontaneously, leading to dissemination of fatty contents within the subarachnoid or ventricular spaces. Though often asymptomatic, rupture can produce a range of neurological symptoms and distinct imaging features. We aim to evaluate the clinical presentation, imaging characteristics, and outcomes of patients with ruptured intracranial dermoid cysts.

We conducted a retrospective review of patients diagnosed with ruptured intracranial dermoid cysts at a tertiary academic medical center from July 1997 to July 2024. Rupture was confirmed by the presence of fat droplets in the CSF spaces on CT and/or MRI. Imaging findings were independently reviewed by two radiologists.

Twenty-two patients (14 female, 8 male; mean age 51.7 years) met inclusion criteria. The most common presenting symptoms were headaches (31.8%). Imaging revealed intraventricular fat in 72.7% of cases and subarachnoid fat in 81.8%, with visible primary cysts in 31.8%. MRI findings included T1 hyperintense fat droplets in all cases, hypointense rims on T2 in 35% of cases, and susceptibility signal loss on SWI in 71%. Follow-up imaging (available in 14 cases) did not show complete resolution of fat droplets, though a reduction in the number of droplets was observed over time.

Ruptured intracranial dermoid cysts are rare but recognizable by their characteristic imaging features, particularly on T1-weighted MRI. While symptoms often improve, residual fat globules persist for years.