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|LETTER TO EDITOR
|Year : 2012 | Volume
| Issue : 4 | Page : 450-452
Free fat droplets from ruptured spinal tumors
Yu Hu, Weiying Zhong, Haifeng Chen, Siqing Huang
Department of Neurosurgery, West China Hospital, Sichuan University, China
|Date of Web Publication||6-Sep-2012|
Department of Neurosurgery, West China Hospital, Sichuan University
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Hu Y, Zhong W, Chen H, Huang S. Free fat droplets from ruptured spinal tumors. Neurol India 2012;60:450-2
A 23-year-old male was admitted for neck pain and mild headache of one-month duration. He had a laminectomy for mature cystic teratoma of the conus medullaris one year back. Neurological examination revealed sensory disturbances and normal muscle strength in the upper limbs. Spinal magnetic resonance imaging (MRI) revealed a long-segment lesion from C1 to T2, hyperintense on both T1- and T2-weighted images, and rim enhancement with gadolinium administration, hypointense on fat-saturation images [Figure 1]. Brain computed tomography (CT) and an MRI scan also showed multiple free fat globules in the Sylvian fissure and lateral ventricles [Figure 2]. He had cervical hemilaminectomy and the spinal cord was punctured from the posterior midline using a 5 ml syringe and yellowish and liquefied fat droplets were aspirated. The cavity was flushed with normal saline and care was taken to prevent dissemination of the cyst contents. The cyst wall was adherent tightly to the surrounding tissues, and only a biopsy was performed. A pathological study showed evidence of chronic inflammation changes. The patient had a near-normal neurological condition, without recurrence, at the latest follow-up.
Ruptured fat-containing tumors (FCTs), with free fat droplet spillage into the intracranial subarachnoid space and ventricular system rather than into the spinal subarachnoid space and spinal cord have been frequently reported. So far only 23 spinal tumors with disseminated fat droplets have been reported in the literature. These tumors are usually benign, congenital, fat-containing tumors, such as teratoma,epidermoid, and dermoid, and are frequently located in the thoracolumbar or lumbosacral region. Although FCTs develop from the embryonic period, most of them present in adult life at an average age of 39 years (range, 20-75 years). A significant male predominance has been observed. FCTs can be spontaneous in origin, may have an iatrogenic cause, or result from a traumatic rupture, ,, and can cause acute aseptic meningitis or other chronic consequences, such as, hydrocephalus or symptomatic central canal dilation.  The symptoms mainly depend on the amount, size, and location of the free fat droplets, and the primary spinal lesion. Fatty contents are consistently hypodense on the CT scan and usually hyperintense on T1- and T2-weighted images on MRI. These fat materials are suppressed on the fat-saturation sequence, which is important to establish the diagnosis. Fat droplets in the subarachnoid space, central canal, and ventricular system usually indicate an underlying FCT,  therefore, MRI of the entire nervous system should be performed to detect the underlying lesion and the associated complications, such as, hydrocephalus and central canal dilation.
|Figure 1: Sagittal T1WI (a) shows a long segment hyperintense intramedullary signal extending from the base of the skull to the T2 level, with perilesional enhancement in the post-contrast T1W fat-saturation image (b) Post operation sagittal T1WI (c) reveals that most of the fat droplets have been removed and the central canal has collapsed|
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|Figure 2: Cranial non-contrast axial MRI (a) reveals hyperintense fat material in the frontal horns of the lateral ventricles, which is confirmed by an axial CT (b)|
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The accumulation of fat materials in the spinal central canal is controversial, because the central canal is rudimentary in adults. Barsi et al. assume that the rudimentary central spinal canal can reopen and serve as a migration pathway for free fat materials into the subarachnoid space.  The presence of an associated syrinx or hydromyia secondary to FCTs may facilitate the central canal to reopen and accumulate fat droplets.  However, free fat droplets may result in macrophages and lymphocyte infiltration, which would result in necrosis, gliosis, and fibrosis leading to the central canal passive occlusion. Discontinuous ruptured free fat droplets may also cause multi-obstructed points along the central canal.
Surgical resection is the treatment of choice for primary spinal FCTs. If possible, gross total resection must be advised, to avoid recurrence and further dissemination of fat material. During the operation, attention must be paid to avoid fat droplet dissemination into the cerebrospinal fluid and the resection bed must be flushed with normal saline.Most of the free fat droplets in the subarachnoid space, ventricles, and central canal need not necessarily be surgically evacuated, because they are clinically silent. However, a close follow-up with serial imaging is important to detect chronic complications, such as, hydrocephalus.
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[Figure 1], [Figure 2]