CASE REPORT Kor J Spine 5(3):215-218, 2008

A Lumbar Disc Herniation Misdiagnosed as A Type I -A Case Report-

Chang-hyun Oh, M.D., Hyeong-chun Park, M.D., Chong-oon Park, M.D., Seung Hwan Yoon, M.D.

Department of , College of Medicine, Inha University, Incheon, Korea

We describe a rare case of an extradural disc herniation mimicking an extradural spinal tumor radiologically. It is often quite difficult to differentiate a sequestered disc from an extradural tumor when the discal fragments are migrated away from the origin. Distinguishable features of clinical and radiological characteristics between sequestered discs and benign intraspinal tumors were discussed. Although a well enhancing spherical mass in the is routinely diagnosed as tumors, a free sequestered disc fragment also should be taken into consideration. This case demonstrates the role and the importance of contrast magnetic resonance imaging and of a clinical history in the diagnosis of disc herniation.

Key Words: Disc herniationㆍNeurofibromatosis type IㆍMagnetic resonance imaging

INTRODUCTION CASE REPORT

A herniated intervertebral disc is by far the most common A 57-year-old woman was admitted to hospital having soft-tissue mass lesion within the lumbar spinal canal. In the experienced pain in the lower back and right leg for 6 absence of epidural scar, computed tomography (CT) and mag- months after the accident of slip-down from a chair. She netic resonance (MR) imaging findings of such a lesion are had MR imaging films which were taken at local hospital, typical, so that the differential diagnosis usually does not and the films showed us two mass lesions on T12 verte- exist, i.e., the disc has the same signal intensity, and the mass bral body level and L5-S1 level. But, MR imaging was taken does not enhance after injection of a contrast agent. Howe- without gadolinium contrast, so we could not estimate the ver, the CT and MR imaging manifestations of a herniated local enhancement of the lesions. She had a medical history, disc2,3,10) represent a spectrum of findings that may even mimic a syncope at 2 years ago, but no medical evaluation was done. a tumor. Multiple spinal mass lesions such as Also she had a diabetic mellitus and hypertensive medical tosis type I usually represent hypointense on a T1 weighted history, and she medicationed orally. She had no history of imaging, and iso- or slightly hyperintense signal intensity on previous lower back surgery and no skin lesions. No medical a T2 weighted imaging and enhance homogenously on history of her first-degree relatives were observed. gadolinium-enhanced MR imaging4,5). A case of multiple mass revealed a positive Laseque's lesions is hereby presented that was misdiagnosed initially as sign, which distinguished from disease of the hip joint, a by imaging, but was confirmed no motor weakness and abnormal deep-tendon reflexs. Straight intraoperatively and histologically as a herniated disc. leg raise test was positive at 60°on right side. The was intact. Plain radiographs of the thoraco- lumbar spine showed nothing abnormal with preservation

● Received: July 15, 2008 ● Accepted: July 30, 2008 ● Published: September 30, 2008 Corresponding Author: Hyeong-chun Park, M.D. Address of reprints: Department of Neurosurgery, Inha University 7-206, 3-Ga, Shinheung-dong, Jung-gu, Incheon, 400-711, Korea Tel: +82-32-890-2948, Fax: +82-32-890-2947, E-mail: [email protected]

Kor J Spine 5(3) September 2008 215 CH Oh, et al. of the disc space heights. planned to remove someday because of no symptomatic lesion, On laboratory test, no definite abnormalities were seen. the small size of mass, the old age of patient, and the opera- Because of the possibility of multiple central tumors like tion refusal. neurofibromatosis type I, the brain and whole-spine MR imaging with contrast enhancement were checked. The brain DISCUSSION and cervical MR imaging were normal findings. Magnetic resornance imaging of thoraco-lumbar spine showed two A herniated intervertebral disc is by far the most com- mass lesions at the levels of a T12 vertebral body and L5- mon soft-tissue mass lesion within the lumbar spinal canal3). S1 space (Fig. 1). The sizes of mass were not changed with Lumbar disc rupture must be considered in the differential previous MR images. These mass enhanced homogenously diagnosis of mass lesions causing nerve root or cauda equina at T12 vertebral body level and heterogeneously at L5-S1 syndromes6). Many case reports show us that many ruptured level after injection of paramagnetic contrast (Gd-DTPA) disc lesions which mimic a tumor. But, there is (Fig. 2). So we diagnosed at first the lesions as a neurofi- no case which has multiple lesions, and it makes us more bromatosis type I which was misdiagnosed. confused to a correct diagnosis. Our clinical presented case At surgery, the lesion was visualized via a L5 total lami- has two spinal mass lesions of different sites in the spinal nectomy. The dura was swollen and immobile. After retra- canal, so in this case we thought neurofibromatosis type I ction of thecal sac at L5 level, the whitish spinal mass at first impression, although each of them has a different compressing thecal sac, was found. The histological finding character, such as a shape and a pattern of enhancement. showed us a degenerative fibrocartilage, which is consistent Because a different principle of surgical approaches, it is with herniation of nucleus pulposus. The patient's postope- important that distinguish between the disc herniation and rative period was uneventful and she had fully recovered the spinal cord tumor5). In the case of disc herniation, the in 1 month. The other lesion of a T12 vertebral body is minimal surgical approach is a basic principle, but in the

Fig.1. Spinal magnetic resonance images of T1 and T2 weighted image. Figure A and B demonstrated us that two multiple spinal mass lesions in T1 weighted image (WI) and T2 WI. Figure C and D demonstrated us lumbar spinal lesion at the level of L5-S1. Figure E and F demonstrated us thoracic spinal lesion at the level of T12. We can easily see that the different shape of each spinal mass.

216 Kor J Spine 5(3) September 2008 HLD Misdiagnosed as NF-I

Fig. 2. Spinal magnetic resonance images which were enhanced by gadolinium contrasts. Upper spinal mass lesion was enhanced by homogeneously, but lower lesion was enhanced by heterogeneously. contrary to remove tumors as much as surgeons can be in differentiate lumbar disc herniation from other conditions7). the surgical field is a basic principle1,8,11). So many neuro- Contrast-enhanced MRI scans are useful to differentiate a surgeons have tried to distinguish the confused mass lesion, herniated disc from a disc space infection or tumor. Peri- and many trials were presented. pheral enhancement around the non-enhancing disc frag- Neurofibromatosis type 1 which we misdiagnosed is an ment can be rarely seen on contrast MRI in cases of the autosomal dominant disorder that affects the bone, the ner- prolonged disc herniation or the disc herniation combined vous system, soft tissue, and the skin, and linked to muta- with hemorrhage9). A herniated disc fragment is rarely tion of neurofibromin chromosome 17q11.212). The diag- enhanced centrally, which is attributed to vascular granula- nostic criteria for neurofibromatosis type 1 are met if 2 or tion tissue infiltrating the fragment9). more of the features listed are present; 1/Six or more caf? Kim et al. reported a different method of a differential au lait macules larger than 5 mm in greatest diameter in diagnosis6). He said that MR imaging has helped clinicians prepubertal individuals and those larger than 15 mm in to diagnose soft tissue lesions correctly, but MRI is still greatest diameter in postpubertal individuals; 2/Two or more not completely accurate. For the purpose of overcoming of any type or 1 plexiform neurofibroma; 3/ radiological limitations, he recommended us magnetic reso- Freckling in the axillary or inguinal regions; 4/ Optic ; nance spectroscopy (MRS) for a differential diagnosis. MRS 5/Two or more Lisch nodules (iris hamartomas); 6/A dis- findings were compared to the histopathologic results from tinctive osseous lesion, such as sphenoid dysplasia or thinning biopsy, and tumor spectra were compared with the spectra of the long bone cortex, with or without pseudoarthrosis; of other benign diseases including disc herniation, which 7/A first-degree relative with NF-1 according to the above can mimic spinal cord tumor. It proved that acquisition of criteria. Although we could not found any meeting criteria in in vivo 1H-NMR signals is possible in human spinal mass this case, we diagnosed at first the lesions as a neurofibroma- lesions on a 1.5 T clinical MRI unit. Just only detection tosis because of the multiple spinal mass lesions on imaging study. of choline in the spinal tumors may indicate that there It is usually not difficult with current MRI techniques to has been some potential in using in vivo 1H-MRS to dis-

Kor J Spine 5(3) September 2008 217 CH Oh, et al. tinguish spinal tumors from disc herniation mimicking spinal on disorders of the spine and peripheral nerves of the cord tumors, non-multiple sclerosis myelitis, and dermoid cysts. American Association of Neurological Surgeons and the However, in spite of their encouraging data, final diagnosis of Congress of Neurological Surgeons. Neurosurgery 29:301- spinal tumor should be needed histological findings to 312, 1991 avoid incorrect managements. 2. Ashkenazi E, Pomeranz S, Floman Y: Foraminal hernia- It was not yet established the treatment of incidental spinal tion of lumbar disc mimicking neurinoma on CT and MR tumor, although it was founded occasionally. In our case, imaging. J Spi Dis 10:448-450, 1997 we initially operated the symptomatic lesion site only and 3. Buirski G: Magnetic resonance singal patterns of lumbar planned another operation in asymptomatic lesion. We discs in patients with low . Spine 17:1199-1204, thought that the incidental spinal tumor would not always 1992 meet the indication of operation and could be delayed the 4. Emamian SA, Skriver EB, Henriksen L, Corsten ME: operation until it evoked the symptom or not presented Lumbar herniated disk mimicking neurinoma. Acta Radiol malignancy character. But, the closed follow-up evaluation 34:127-129, 1993 for the tumor would be recommended. 5. Kim SJ, Song JH, Kim MH, Park HK, Kim SH, Shin Generally, the clinical symptoms of isolated HNP are far KM, et al: Sequestered disc mimicking benign neurogenic different of spinal mass lesion. Non-progressing definite tumor. Report of 2 cases. J Korean Neurosurg Soc 26: neurological symptom, a severe pain, and a short duration of 596-599, 1997 symptom can be a clue of differential diagnosis. Moreover, the 6. Kim YG, Choi GH, Kim DH, Kim YD, Kang YK, Kim radiologic findings such as a different enhancing pattern of JK: In vivo proton magnetic resonance spectroscopy of human different sites can help the differential diagnosis between the spinal mass lesions. J Spinal Disord Tech 17:405-411, neurofibromatosis type I and a herniated lumbar disc. Con- 2004 sidering clinical history of this case, we initially ignored the 7. Ramsey RG: Neuroradiology, ed 2. Philadelphia: Saunder, history of a falling injury, but after gaining histological fin- 1994, pp793 dings of simple disc herniation, we could retrospectively 8. Rossaco SJ, Berman AT: Surgical management of lumbar remind that the trauma history was the clue of feasible diag- disc disease. Radiol Clinic North Am 21:377-393, 1983 nosing a disc herniation rather than a neurofibromatosis type I. 9. Scott WA: Magnetic Resonance Imaging of the Brain and Spine, ed 3. Philadelphia: Lippincott Williams & CONCLUSION Wilkins, 2002, pp1527-1529 10. Vadala G, Dore R, Garbagna P: Unusual osseous changes We herein present a case of an extradural disc herniation in the lumbar herniated disks. CT features. J Comput at L5-S1 mimicking an extradural spinal tumor, such as a neu- Assist Tomogr 9:1045-1049, 1985 rofibromatosis type I that demonstrates the role and the 11. Williams AL, Haughton VM, Daniels DL, Grogan JP: importance of contrast MR imaging and of a clinical his- Differential CT diagnosis of extruded nucleus pulposus. tory in the diagnosis of disc herniation. Radiology 148:141-149, 1983 12. Ward K, O'Connell P, Carey JC, Leppert M, Jolley S, REFERENCES Plaetke R, et al: Diagnosis of neurofibromatosis I by using tightly linked, flanking DNA markers. Am J Hum 1. Abramovitz JN, Neff SR: Lumbar disc surgery: Results Genet 46:943-9, 1990 of prospective lumbar discectomy study of the joint section

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