Rupture of spinal dermoid cyst with intracranial dissemination: Report of a case and review of the literature
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.236984
Source of Support: None, Conflict of Interest: None
Dermoid cysts are dysembryogenic tumors, presumably resulting from inclusion of ectodermal elements during neurulation in the third to fifth week of embryogenesis., Most commonly located in the lumbosacral spine, they are associated with spinal dysraphism of some form in the majority of cases. Upper thoracic and cervical locations are rare., Spinal dermoid rupture is an uncommon entity resulting most commonly in chemical meningitis due to irritative effects of disseminated cholesterol debris.,, Rupture may be into the central spinal canal or the intracranial compartment (subarachnoid cisternal and intraventricular spaces).,,,,,, Management consists of treatment of meningitis and excision of the spinal lesion. The present article aims to report one such case of ruptured spinal dermoid with intracranial dissemination and also to provide a review of literature on this uncommon topic.
The details of our case were retrieved from the operative records. For review purpose, the following keywords were searched on PubMed/MEDLINE and Index Medicus: “Spinal dermoid cyst,” “dermoid rupture,” “spontaneous dermoid rupture,” “fat dissemination,” “intracranial dissemination,” and “aseptic meningitis.” Among all reported cases of spinal dermoid cyst rupture, only those articles pertaining to intracranial fat dissemination were analyzed. Cases of cranial dermoids and spinal dermoid rupture with isolated spinal spread without cranial involvement were excluded from the analysis. A detailed literature review contemplating the demographic, imaging, and outcome parameters of such lesions is provided.
An 18-year-old male patient presented to the casualty services with a high-grade fever of 1 month's duration, along with headache, vomiting, and neck stiffness of 15 days' duration. He had similar complaints 1 year back and was diagnosed as having meningitis, which was conservatively managed at an outside hospital. At presentation, he was alert and conscious, and his neurological examination was normal. There were no cutaneous stigmata of spinal dysraphism. A noncontrast computed tomography (CT) of the brain showed diffuse hypodense droplets (negative Hounsfield units) in both the lateral ventricles, subarachnoid cisternal spaces, and cerebral sulci suggestive of diffuse fat dissemination [Figure 1]a. Magnetic resonance imaging (MRI) confirmed the presence of fat droplets. These droplets were uniformly hyperintense on T1 and T2 sequences, showed suppression on fat-saturation images, and there was no enhancement [Figure 1]b,[Figure 1]c,[Figure 1]d,[Figure 1]e. Mild ventriculomegaly was noted. No intracranial dermoid was seen. With such an extensive intracranial fat dissemination manifesting as chemical meningitis, a spinal MRI was performed to rule out a dermoid cyst. A large D1–D4 intramedullary lesion was noted, which on T1 sequences had a thin rim of hyperintense tissue with a large internal hypointense component, and was mostly hyperintense with a central hypointensity on T2 sequences, suggestive of a fat-containing lesion such as a dermoid cyst [Figure 2]a,[Figure 2]b,[Figure 2]c,[Figure 2]d. Segmentation anomalies of the D3 and D4 vertebral bodies could be identified. He was operated after the meningitis was treated. A D1–D4 laminoplasty and subtotal excision was performed. The cyst contained abundant amounts of hair admixed with calcification and cheesy material [Figure 2]e. In view of the adherence of the cyst wall to the cord substance, it was subtotally excised. Postoperatively, he had transient weakness of lower limbs, which improved to a normal state in a week's duration. Postoperative MRI done at 24 months' follow-up showed a small residual portion of the cyst [Figure 3]. At the last clinical follow-up of 36 months, he was doing well, with no fresh episodes of meningitis.
During the third to fifth week of embryogenesis, abnormal inclusion of ectodermal cell rests into the spinal canal at the time of neural tube closure leads to the formation of inclusion cysts such as dermoid and epidermoid cysts.,,, An iatrogenic origin has also been described.,
Dermoid cysts are rare, benign, tumor-like lesions comprising approximately 1% of both intracranial and spinal tumors.,,, They have a slight male preponderance. They are revealed most commonly during the second to third decades.,,, Their high incidence occurs in the lumbosacral region involving the conus and cauda equina. Upper thoracic (10%) and cervical (5%) lesions are rare., Dermoids are associated with a dermal sinus in 20% of the cases.,, Clinical features depend on the location of the lesion and are due to its irritative or compressive effects on adjacent structures.,
The rupture of a dermoid cyst is a well-known phenomenon and can be spontaneous, iatrogenic, or traumatic in origin., A ruptured dermoid may have myriad presentations. Chemical/aseptic meningitis is the most common feature after rupture, which is due to the irritative effects of the disseminated cholesterol debris.,,,, The patient may be asymptomatic or there may be headache, vomiting, seizures, coma, infarct, and rarely, death.,,,, Headache might occur because of compression of adjacent structures, chemical meningitis, or hydrocephalus due to obstruction of cerebrospinal fluid (CSF) pathways by lipid droplets., It has been noticed that symptoms occurring after the dermoid rupture are not seen acutely but are usually delayed for a period ranging from 3 months to 7 years. This is probably due to the time required for the irritative effects of the lipid debris to develop.,, Intracranial dermoids are most prone to rupture. Uncommonly, spinal dermoids rupture, resulting in aseptic meningitis or, rarely, bacterial meningitis (due to invasion of skin organism along a sinus track).,, Various hypotheses have been proposed for the intracranial dissemination of fat droplets. Scearce et al., stated that lipid droplets float in the CSF and are passively conveyed by CSF movement to the ventricles from the perimedullary subarachnoid space by retrograde flow through the Foramina of Luschka More Details and Magendie., Another theory postulates that direct communication between the central canal and the intracranial subarachnoid space favors this lipid spread. The latter theory, however, is unlikely in all cases, as the central canal is nonpatent in adults. Rupture of the lesion might also be related to trauma, according to a few authors.,
Fat droplets appear as highly hypodense (with negative Hounsfield units of 0 to − 150) on a CT image., The advent of MRI has increased the rate of detection of spontaneous dermoid rupture, previously considered a fatal condition.,, On MRI, dermoids are usually hyperintense on T1-weighted images and variable on T2 sequences, but the hyperintensity might be absent if there is a little amount of lipid.,,, In our case, the lipid droplets appeared uniformly hyperintense on T2 sequences. Fat suppression sequences have higher specificity, as dermoids suppress on these sequences reflecting the presence of lipid.,,,, Dermoids usually do not show enhancement on contrast images. Intracranial dissemination of a ruptured dermoid produces characteristic imaging features including free lipid droplets, seen as T1 hyperintensities in the subarachnoid spaces and as intraventricular fat–fluid levels., Rarely, hydrocephalus might be present.,, Also, floating of fat droplets in the ventricles can occasionally be seen on MRI on changing the position of the patient from supine to prone. In case of nonvisualization of an intracranial source of fat dissemination, many authors have suggested MRI of the entire spine to look for a spinal dermoid cyst.,
The mean age at presentation of such lesions is 40.6 years (range, 18–75 years), and all cases have been reported exclusively in male patients. In our article, it was an 18-year old male patient. This age is much lesser than the aforementioned mean age. The first description of spinal dermoid rupture was provided by Barsi et al., in 1992, and since then, only a handful of such cases have been reported.,,,,,,,,,, Among these, spread into the spinal subarachnoid space or the central canal is relatively common, while reports of dissemination into the intracranial compartment (either cisternal or intraventricular spaces) are very few [Table 1].,,,,,,,,,,,, All such ruptured spinal dermoids were located in the lumbosacral region.
We arbitrarily categorized them into three types based on the relationship between the spinal mass and their intracranial dissemination: Type I, symptomatic spinal–symptomatic cranial; Type II, symptomatic spinal–asymptomatic cranial; and Type III, asymptomatic spinal–symptomatic cranial. Most reports pertain to the second category.,,,, Reports by Scearce, Cavazzani, Calabro, and Goyal et al., belong to the first category.,,, Apart from our case, the only other case related to the third category was reported by Altay et al. Also, ours is the only case of an upper thoracic (D1–D4) dermoid presenting with rupture into any compartment (central canal/intracranial).
Treatment includes administration of steroids, analgesics, and antibiotics and surgical resection of the spinal lesion. The role of antibiotics is controversial. Antibiotics may be given in cases of suspected secondary bacterial infections. There is often a dramatic response to steroids, especially in the acute period, because the meningitis is usually aseptic or chemical in nature. Steroids help by reducing the inflammatory process. Maximal safe resection should be the goal of surgery. In case of adherence of the cyst to the cord substance, it is always wise to leave behind a rim of tissue and perform a subtotal or near-total resection. Reports of surgical outcome are very few. There has been one mortality reported so far. Hydrocephalus is a rare sequelae of such rupture and has been documented in two reports (four cases). Among these, two cases were managed with ventriculoperitoneal shunt for suspected congenital obstructive hydrocephalus. This obstruction occured because of fat droplets blocking the aqueduct of Sylvius or the outlet foramina of Lushka.,
Although imaging and management aspects have been well described in previous reports, the following points of uncertainty need to be addressed:
Rupture of spinal dermoids is uncommon, and intracranial dissemination is rare. MRI is the diagnostic modality of choice. Most lesions that rupture belong to the symptomatic spinal–asymptomatic cranial type and have been noted exclusively in male patients. The long-term prognosis of intracranial fat dissemination with regard to symptom recurrence and radiological resolution remains unknown. We conclude that in cases of nonvisualization of an intracranial source of cisternal and ventricular fat dissemination, especially when the phenomenon is associated with recurrent episodes of meningitis, a spinal MRI should always be done to rule out a primary spinal dermoid cyst.
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[Figure 1], [Figure 2], [Figure 3]