Objective: Intracranial dermoid cysts are pathologically characterized by a thick, stratified squamous epithelium cyst wall containing dermal elements. Rupture into the subarachnoid spaces and ventricles is extremely rare. We review the clinical, radiographic, and surgical features of eight ruptured dermoid cysts.
Methods: We retrospectively evaluated five surgically treated patients with pathologically proven ruptured dermoid cysts. Clinic notes, operative reports, and neuroimaging, including initial computed tomographic and magnetic resonance imaging scans, were reviewed. Imaging was also available on three outside patients reviewed by members of our radiology department.
Results: The most common presentations were headaches (57%) and seizures (42%), followed by hydrocephalus (29%) from intraventricular rupture. These lesions were consistently hypodense on computed tomographic scans and hyperintense on T1-weighted images with minimal to no enhancement after gadolinium administration. Disseminated fat droplets were present in the subarachnoid space in both cerebral hemispheres in all patients, and five patients had intraventricular rupture with fat-fluid levels in the ventricles. Gross to near-total resection of the primary lesion was achieved in all five surgically treated patients treated at our institution. Four patients had remnant tumor capsules adherent to neurovascular structures that were unresectable. Repeat resection was performed for one recurrence; there were no further recurrences during a follow-up period of 2 to 134 months (mean, 65.6 mo). Two patients with preoperative hydrocephalus eventually required ventriculoperitoneal shunting.
Conclusion: Ruptured intracranial dermoid cysts represent 0.18% of all central nervous system tumors surgically treated in our institution during a 12-year period. The presence of disseminated fat droplets in the subarachnoid space or ventricles on neuroimaging is diagnostic for a ruptured dermoid cyst. Gross total removal is achievable; however, residual tumor capsules adherent to neurovascular structures should be left behind to minimize complications.