CT: THE JOURNAL OF COMPUTED TOMOGRAPHY 1987:11:181-183 181 MAGNETIC RESONANCE IMAGING OF INTRASPINAL EPIDERMOID CYST: A CASE REPORT JEFFREY PHILLIPS, MD, AND LEE CHIU, MD Introspinal epidermoid cysts are considered rare le- sions. We report such a case in a IZ-year-old boy that was diagnosed by magnetic resonance imaging. The magnetic resonance imaging characteristics of the lesion and the importance of proper imaging se- quences are discussed. KEY WORDS: Intraspinal epidermoid; Spinal epidermoid cyst; Magnetic resonance imaging; Spine; Cysts The uniqueness and rarity of epidermoid cysts of the spine have prompted numerous case reports in the literature. We describe an additional case here, diagnosed by magnetic resonance imaging (MRI). CASE REPORT A l&year-old El Salvadoran boy presented with a complaint of sharp pain in the right calf that had been occurring intermittently for 5 years. He also had begun experiencing pain in his lower back, with radiation down both legs. The pain was aggra- vated by walking. The patient was the product of a normal term pregnancy. He had had multiple hospitalizations as a child in El Salvador for what was termed “asthma,” and at 3 months of age had had a lumbar puncture. Physical examination was remarkable for mild (4 + /5) weakness in the right lower extremity with From the Department of Radiology, Harbor-UCLA Medical Center, Torrance, California. Address reprint requests to: Lee Chiu, MD, Department of Ra- diology, Harbor-UCLA Medical Center, Torrance, California 90509. Received June 1986. 8 1987 by Elsevier Science Publishing Co., Inc. 52 Vanderbilt Avenue. New York, NY 10017 fl149-936X/R7/$3.,50 decreased tone bilaterally, and foot drop. Straight leg raises elicited radiating pain at 30” on the right and at 45” on the left. He had poor heel-walking ability, but could toe-walk. Plain radiographs and a computed tomography FIGURE 1. Midline sagittal image [SE Tl weighted, TE 26/TR 500) shows a low-intensity intradural lesion near L-4. The tumor is difficult to differentiate from surround- ing cerebrospinal fluid.
Transcript
CT: THE JOURNAL OF COMPUTED TOMOGRAPHY 1987:11:181-183 181
MAGNETIC RESONANCE IMAGING OF INTRASPINAL EPIDERMOID CYST: A CASE REPORT
JEFFREY PHILLIPS, MD, AND LEE CHIU, MD
Introspinal epidermoid cysts are considered rare le- sions. We report such a case in a IZ-year-old boy that was diagnosed by magnetic resonance imaging. The magnetic resonance imaging characteristics of the lesion and the importance of proper imaging se- quences are discussed.
The uniqueness and rarity of epidermoid cysts of the spine have prompted numerous case reports in the literature. We describe an additional case here, diagnosed by magnetic resonance imaging (MRI).
CASE REPORT
A l&year-old El Salvadoran boy presented with a complaint of sharp pain in the right calf that had been occurring intermittently for 5 years. He also had begun experiencing pain in his lower back, with radiation down both legs. The pain was aggra- vated by walking.
The patient was the product of a normal term pregnancy. He had had multiple hospitalizations as a child in El Salvador for what was termed “asthma,” and at 3 months of age had had a lumbar puncture.
Physical examination was remarkable for mild (4 + /5) weakness in the right lower extremity with
From the Department of Radiology, Harbor-UCLA Medical Center, Torrance, California.
Address reprint requests to: Lee Chiu, MD, Department of Ra- diology, Harbor-UCLA Medical Center, Torrance, California 90509.
Received June 1986. 8 1987 by Elsevier Science Publishing Co., Inc. 52 Vanderbilt Avenue. New York, NY 10017 fl149-936X/R7/$3.,50
decreased tone bilaterally, and foot drop. Straight leg raises elicited radiating pain at 30” on the right and at 45” on the left. He had poor heel-walking ability, but could toe-walk.
Plain radiographs and a computed tomography
FIGURE 1. Midline sagittal image [SE Tl weighted, TE 26/TR 500) shows a low-intensity intradural lesion near L-4. The tumor is difficult to differentiate from surround- ing cerebrospinal fluid.
182 PHILLIPS AND CHILI CT: THE JOURNAL OF COMPUTED TOMOGRAPHY VOL. 11 NO. 2
(CT) scan of the lumbar spine were interpreted as normal. MRI was done with a 0.5 Tesla Picker unit. Images were obtained in both sagittal and axial planes using 5-mm contiguous sections, and a data matrix of 256 X 256. Multiple spin-echo sequences in the sagittal plane were acquired using echo time (TE) of 26 msec and a repetition time (TR) of 500 msec, a TE of 120 msec and a TR of 2500 msec, and with a multiecho sequence of a TE 40 msec and 80 msec with TR of 2000 msec. Axial images were ob- tained using a TE of 40 msec and 80 msec with a TR of 1000 msec.
The scan demonstrated an intradural mass at the L3-4 level, centered predominantly at L4. The le- sion appears isointense to cerebrospinal fluid on the Tl-weighted (Figure 1) and heavily TZweighted images, but was easily seen with the more interme-
FIGURE 2. (A) Intermediate-weighted MRI study (TE JO/ TR 2000) clearly demonstrates the tumor because of en- hanced contrast between it and the surrounding cerebro- spinal fluid. (B) Second echo, more T2-weighted MRI
The patient underwent a laminectomy, at which time an epidermal inclusion cyst adherent to the nerve roots at L4 was found. The pathologic speci- men consisted of a pearly, white-tan tissue com- prising keratinaceous debris, with a border of epi- thelial tissue.
DISCUSSION
The relationship between spinal epidermoids and previous lumbar punctures has been well described and exemplified in the literature (l-4). Based largely on an extensive review by Manno and asso- ciates (l), this association is said to account for over 40% of all spinal epidermoids, and most of those
study (TE 80iTR 2000) again easily shows the mass. The protein-rich (shortened Tl) cyst appears significantly brighter than the surrounding cerebrospinal fluid.
APRIL 1987 MRI OF EPIDERMOID CYST 183
occurring in the lumbar region. Experimental work has been done to support the iatrogenic theory. Most conclusively, it was possible to produce der- moid and epidermoid tumors in the spinal canal of rats by direct implantation of skin fragments (5).
In the case described here, the patient was said to have had a spinal tap at several months of age in El Salvador for possible sepsis. Although the time interval between lumbar puncture and discovery of tumor is typically 5-6 years (l-3), instances of 12 or more years have been cited (1). It also seems likely that our patient was symptomatic for several years prior to his presentation at Harbor-UCLA Medical Center.
Until recently, radiographic diagnosis of this en- tity has been limited to myelography and metriza- mide computed tomography (6). To our knowledge, this is the first reported case of intraspinal epider- moid cyst diagnosed by MRI. The advantages of MRI for evaluating spinal pathology are now well recognized, and include its noninvasiveness, ease of multiplanar imaging, and improved tissue contrast and tissue characterization (7, 8).
The MRI tissue characterization of the lesion in this case is noteworthy. Houston and Hinke (9) re- cently published a case of a suprasellar epidermoid that was bright on Tl-weighted images because of its lipid (short Tl) content. We have seen another example of an epidermoid near the craniocervical junction that had low intensity on Tl-weighted im- ages. This would seem to agree with the findings of Kjos et al. (10). In their series of cystic intracranial lesions, they cited a pattern for proteinaceous cysts similar to that seen in our current case. To add fur- ther confusion, Monajati and colleagues (11) de- scribed the keratinous portion of a spinal teratoma as being intermediate intensity on Tl-weighted im- ages. This disparity most likely reflects variable lipid and protein composition in these lesions. Ep- idermoids are described as a mass of desquamated cells containing keratohyalin (1). Cholesterol crys- tals are characteristically present. The protein con- centration is variable and was used by Nagashima et al. (12) to explain the occasional high-density ep-
idermoid cyst on CT. As MRI experience accumu- lates with these lesions, greater histopathologic cor- relation should be possible.
It also illustrates the importance of intermedi- ately Tl/TZ-weighted or spin-density sequences in the diagnosis of some intradural masses. The lesion in our patient may have been easily overlooked on more heavily Tl- and T&weighted images because of poor contrast between cerebrospinal fluid and tu- mor. In their review of spinal cord tumors, Di Chiro et al. (7) alluded to a similar problem in distin- guishing the edges of neoplasms from cerebrospinal fluid on T2-weighted images. It is hoped that aware- ness of this phenomenon will lead to its avoidance as a diagnostic problem.
REFERENCES 1. Manno NJ, Uihlein A, Kernohan JW: Intraspinal epider-
Sarma DP, Carter CF, Weilbaecher TG: Intraspinal epider- moid cyst. J Surg Oncol 1984;25:64-6. Van Gilder JC, Schwartz HG: Growth of dermoids from skin implants to the nervous system and surrounding spaces of the newborn rat. J Neurosurg 1967;26:14-20. Donoghue V, Chuang SH, Chilton SJ, et al: Intraspinal epi- dermoid cysts. J Comput Assist Tomogr 1984;8:143-4. Di Chiro G, Doppman JL, Dwyer AJ, et al: Tumors and arte- riovenous malformations of the spinal cord: assessment us- ing MR. Radiology 1985;156:689-97. Medic MT, Hardy RW, Weinstein MA, et al.: Nuclear mag- netic resonance of the spine: clinical potential and limita- tion. Neurosurgery 1984;15:583-92. Houston LW, Hinke ML: Neuroradiology case of the day. AJR 1986;146:1094-5. Kjos BO, Brant-Zawadzki M, Kucharczyk W, et al.: Cystic in- tracranial lesions: magnetic resonance imaging. Radiology 1985;155:363-9. Monajati A. Spitzer RM, Wiley JL, Heggeness L: Case report: MR imaging of a spinal teratoma. J Comput Assist Tomogr 1986;10:307-10. Nagashima C, Takahama M, Sakaguchi A: Dense cerebello- pontine epidermoid cyst. Surg Neurol 1982;17:172-7.
