Traumatic sacral dermoid cyst rupture with intracranial subarachnoid seeding of lipid particles: illustrative case

Abstract

Background: Intracranial deposits of fat droplets are an unusual presentation of a spinal dermoid cyst after spontaneous rupture and are even more uncommon after trauma. Here, the authors present a case with this rare clinical presentation, along with a systematic review of the literature to guide decision making in these patients.

Observations: A 54-year-old woman with Lynch syndrome presented with severe headache and sacrococcygeal pain after a traumatic fall. Computed tomography of the head revealed multifocal intraventricular and intracisternal fat deposits, which were confirmed by magnetic resonance imaging (MRI) of the neuroaxis; in addition, a ruptured multiloculated cyst was identified within the sacral canal with proteinaceous/hemorrhagic debris, most consistent with a sacral dermoid cyst with rupture into the cerebrospinal fluid (CSF) space. An unruptured sacral cyst was later noted on numerous previous MRI scans. In our systematic review, we identified 20 similar cases, most of which favored surgical treatment.

Lessons: Rupture of an intraspinal dermoid cyst must be considered when intracranial fat deposits are found in the context of cauda equina syndrome, meningism, or hydrocephalus. Complete tumor removal with close postoperative follow-up is recommended to decrease the risk of complications. CSF diversion must be prioritized if life-threatening hydrocephalus is present.

Keywords: CSF = cerebrospinal fluid; CT = computed tomography; MRI = magnetic resonance imaging; cyst rupture; fatty deposits; intraspinal dermoid; intraventricular and subarachnoid spaces.

FIG. 1.

Axial (A and B) and sagittal (C) cranial CT scans show multifocal intraventricular and intracisternal fat (gray arrows), which appeared new compared with positron emission tomography/CT performed 1 year before the patient’s presentation at our institution. Axial (D and E) and sagittal (F) MRI scans of the brain confirmed the presence of multifocal fat lobules within the nondependent aspects of the lateral ventricles and the basal cisterns (white arrows). A right parietal scalp hematoma was observed, with no acute intracranial hemorrhage or depressed skull fracture. Ventricles, sulci, and basal cisterns were within normal limits.

FIG. 2.

Sagittal (A) and axial (B) MRI scans from 1 year before presentation showed a sacral lesion without evidence of rupture or hemorrhage. On this admission, sagittal (C) and axial (D) MRI scans of the sacral spine revealed an intrathecal multilobulated cystic lesion centered within the central/right paracentral sacral canal at S2–3. The lesion demonstrated few foci of nodular T1 hyperintensity with subsequent saturation on short tau inversion recovery images, consistent with fatty components. Layering fluid-fluid level within the lesion was consistent with proteinaceous/hemorrhagic debris. The presence of additional layering fluid-fluid level within the distal thecal sac of the lumbosacral junction was consistent with the CSF space’s communication.

FIG. 3.

Axial cranial MRI scans showed a mild increase in the overall burden of foci of fat disseminated within the ventricular system and additional CSF spaces 1 month after patient’s fall. Specifically, there were now foci of fat over the cerebellum (A) and within the sylvian fissures (B) and interhemispheric fissure anteriorly (C). These findings represented redistribution, with decreased volume of the focal lipid signal seen in the right side of the suprasellar cistern on the previous MRI scan. Nondependent foci of fat within the right more than the left lateral ventricles and extending throughout the basal cisterns were still observed, without hydrocephalus. Six-month follow-up MRI revealed a slight decrease in prominence of fat lobules disseminated throughout the CSF spaces, which may reflect continued breakdown of larger fat lobules, with overall similar distribution of the fat in basal cisterns over the cerebellum (D) and within the sylvian (E) and interhemispheric (F) fissures. The ventricular system remained unchanged in size and configuration.

FIG. 4.

PRISMA workflow for our systematic review.