Abstract
We describe 5 cases of osteochondroma (OC) originating from lumbosacral spine which caused radiculopathy. Four cases originated from the lumbar spine; all from L4 inferior articular process and presented L5 radiculopathy, the other one case originated from the sacrum; the case from S1 superior articular process presented L5 radiculopathy. In all cases, definitive diagnosis was made with histopathological findings; typical cartilaginous capping was confirmed. The functional recovery was completed in all 5 cases. As for imaging study, postmyelography computed tomography revealed the most diagnostic tool for understanding the relationship between nerve tissue and the tumor. In all 5 patients, the tumors contained a high signal intensity on T2-weighted images in the central medullary area. OCs are sometimes difficult to diagnose because they mimic other conditions like bony spur formation due to osteoarthritis, so we should never fail to confirm the histopathological diagnosis of such lesions when suspected.
Keywords: osteochondroma, lumbar, sacrum, radiculopathy, cartilaginous cap
Introduction
Although osteochondroma (OC) is a common benign tumor, OC of the spine is a rare manifestation. Spinal OCs are more often located in the cervical and upper thoracic vertebrae, whereas the inferior thoracic, lumbar and especially sacral levels are rarely involved. We describe 5 cases of OC originating from lumbosacral spine that caused L5 radiculopathy. In all cases, histological study confirmed the diagnosis of OC with cartilaginous capping.
Case Reports
Patient 1: A 57-year-old man presented with right leg pain over L5 dermatome for about 6 years. Computed tomography after myelography (CTM) showed a high density mass with medullary continuity between the tumor and the vertebra arising from right L4 inferior articular process, projecting into spinal canal (Fig. 1a). The lesion contained central cancellous bone displaying high signal intensity in T2-weighted image (Fig. 1b). Lumbar laminectomy was performed and the bony mass compressing right L5 nerve root was resected. The patient did not complain of symptoms at 6 years follow-up.
Fig. 1.
(Patient 1) Computed tomography after myelography showed a bony tumor (arrow) with cortical and medullary continuity with inferior articular process of the right L4 vertebra (a). The lesion contained central cancellous bone (asterisk) displaying high signal intensity in T2-weighted image (b).
Patient 2: A 63-year-old woman presented with a 9-month history of motor weakness at right lower extremity (tibialis anterior and extensor hallucis longus) and numbness over right L5 dermatome. CTM showed a bony mass with cortical and medullary continuity with superior articular process of the right S1 vertebra (Fig. 2a). Magnetic resonance imaging (MRI) showed a high intensity cancellous area in T2-weighted image (Fig. 2b). The bony mass was resected via a right partial hemilaminectomy at the L5-S1 level. The mass severely compressed dural theca and right L5 nerve root. Her motor weakness gradually improved and she did not complain of symptoms at the 7 years follow-up.
Fig. 2.
(Patient 2) Computed tomography after myelography showed a bony mass (arrow) with cortical and medullary continuity with superior articular process of the right S1 vertebra (a). Magnetic resonance imaging showed a high intensity cancellous area (asterisk) in T2-weighted image (b).
Patient 3: A 48-year-old woman presented with severe low back and left leg pain over L5 dermatome for a few years. MRI showed a high signal intensity medullary area within the tumor arising from right L4 inferior articular process. The bony mass compressing the right L5 nerve root was resected via a right partial hemilaminectomy at the L4-5 level. She is free from leg pain, but still shows slight low back pain at the 3 years follow-up.
Patient 4: A 32-year-old man presented with a 2-year history of pain involving right buttock and lateral surface of thigh. CTM showed a small bony tumor arising from inferior articular process of the right L4 vertebra (Fig. 3a). The cortex of the tumor was in continuity with the inferior articular process of the right L4 vertebra compressing right L5 nerve root. MRI showed a high signal intensity medullary area within the tumor arising from right L4 inferior articular process (Fig. 3b). The tumor with smooth surface was meticulously resected via a right partial hemilaminectomy at the L4-5 level (Fig. 4a). Histological diagnosis was OC (Fig. 4b). The patient became symptom-free immediately after surgery. At the 19 months follow-up, the postoperative course was uneventful (Fig. 4c).
Fig. 3.
(Patient 4) Computed tomography after myelography showed a small bony tumor (arrow) with cortical and medullary continuity with inferior articular process of the right L4 vertebra (a). Magnetic resonance imaging showed a high intensity cancellous area (asterisk) in T2-weighted image (b).
Fig. 4.
(Patient 4) A macroscopic photograph of the surface of the tumor. The tumor is covered with a smooth cartilaginous capping (a). A photomicrograph showing cartilaginous capping (▴), the mature trabecular bone (★) and fatty bone marrow (asterisk) (H & E, original magnification ×10, b). Postoperative computed tomography (19 months) scan shows the absence of tumor recurrence (c).
Patient 5: A 62-year-old man presented with a 6-month history of pain involving bilateral buttocks and legs. CTM showed a small bone spicule continuing with inferior articular process of the right L4 vertebra. MRI showed a high intensity mass in the T2-weighted image. The tumor was resected via a right partial hemilaminectomy at the L4-5 level. He was relieved from pain. At 1 year follow-up, the postoperative course was uneventful.
Discussion
OC is caused by the separation of a fragment of growth plate cartilage, which grows as a result of progressive enchondral ossification, leading to subperiosteal osseous excrescence with a cartilage cap that projects from the bone surface. Enchondral ossification leads to medullary bone with a fatty or hematopoietic marrow.1) OC is a common tumor affecting bone. OCs are classified as either solitary or multiple. Solitary OCs develop in a single bone and are not hereditary. Multiple OCs can occur either spontaneously or in an autosomal dominant disorder known as hereditary multiple exostoses (HME). The lesions are rarely found in the spine; only 1.3% to 4.1% of solitary OCs and 3% to 9% of HME arise in the spine.2–5)
Symptomatic OCs compressing the neural structures are rare, because the majority of these lesions grow out of the spinal canal.6,7) Spinal OCs are more often located in the cervical and upper thoracic vertebrae, whereas the inferior thoracic and lumbar levels are rarely involved, especially sacrum.8) In the English language literature, there are only 11 reported cases of symptomatic OC in the lumbar spine with sufficient information about the patient's age, sex, symptom, the situation of the tumor, and the outcome.6,7,9–14) In this report, we presented additional 4 cases of OCs arising from lumbar vertebra; all tumors originated from right L4 inferior articular process and presented L5 radiculopathy (Table 1). As to the symptomatic OC in the sacral spine, Sung et al. reported their experience of 54 primary tumors originated from the sacrum including 2 cases of OCs in 1987.15) In the report, there is little information about the patient's age, sex, symptom, the situation of the tumor, and the outcome. To the best of my knowledge, Hanakita and Suzuki reported the first case in 1988 with detailed information.16) Adding our new case (Patient 2), there are only 4 reported cases of symptomatic OCs originating from the sacrum (Table 2).16–18) Complete excision of the cartilaginous component is recommended to decrease the likelihood of local recurrence.18) Malignant transformation to chondrosarcoma is also reported to be 10% to 30% in HME as compared to 1% to 5% in solitary OC, so complete excision of such lesion is very important.6,19) In the present report, using microscope in all surgery, no recurrence was observed for more than 1 year after total excision of the tumor including the cartilaginous cap. According to 11 reported cases with present 4 cases (Table 1), the origin of symptomatic lumbar spinal OCs was from articular process in 9 cases (60%), lamina in 3 cases (20%), pedicle in 2 cases (13%), and vertebral body in 1 case (7%).6,7,9–14) Predominance of articular process is explained by the existence of so-called secondary ossification center. Secondary ossification centers lie in the spinous process, transverse process, articular process, and the endplate of vertebral body. The cartilage of these secondary ossification centers could be the origin of aberrant islands of cartilaginous tissue that cause OC to form.6)
Table 1.
Literature review of reported cases of symptomatic lumbar exostoses
| Author & year | Age (yrs), sex | Level | Site | Presentation | Lesion type | Outcome |
|---|---|---|---|---|---|---|
| Urso et al. (1977)12) | 9, M | L4 | Lamina | Cauda equina synd. | HME | Good |
| van der Sluis et al. (1992)13) | 26, F | L4 | AP | L5, S1 radiculopathy | SOC | ? |
| Fiumara et al. (1999)6) | 35, F | L5 | AP | S1 radiculopathy | SOC | Good |
| Fiechtl et al. (2003)9) | 8, F | L4 | Lamina | L4, 5 radiculopathy | HME | Good |
| Ohtori et al. (2003)7) | 56, M | L3 | AP | L4 radiculopathy | SOC | Good |
| 55, F | L4 | AP | L5 radiculopathy | SOC | Good | |
| Gürkanlar et al. (2004)10) | 35, M | ?? | ?? | L4, 5 radiculopathy | SOC | Good |
| Xu et al. (2009)14) | 38, M | L5 | Lamina | L5 radiculopathy | SOC | Good |
| Lotfinia et al. (2010)11) | 29, M | L4 | Pedicle | L5 radiculopathy | HME | Good |
| 58, M | L5 | VB | Cauda equina synd. | SOC | Good | |
| 17, M | L3 | AP | L4 radiculopathy | HME | Good | |
| Present study | 57, M | L4 | AP | L5 radiculopathy | SOC | Good |
| 48, F | L4 | AP | L5 radiculopathy | SOC | Good | |
| 32, M | L4 | AP | L5 radiculopathy | SOC | Good | |
| 62, M | L4 | AP | L5 radiculopathy | SOC | Good |
AP: articular process, F: female, HME: hereditary multiple exostoses, M: male, SOC: solitary osteochondroma, VB: vertebral body.
Table 2.
Literature review of reported cases of symptomatic sacral exostoses
| Author & year | Age (yrs), sex | Level | Site | Presentation | Outcome |
|---|---|---|---|---|---|
| Sung et al. (1987)15) | ? | Below S3 | ? | Good | |
| ? | ? | ||||
| Hanakita et al. (1988)16) (our case) | 42, F | S1 | Lamina | Urinary disturbance, hypesthesia | Good |
| Agrawal et al. (2005)17) | 14, M | ? | Sacral ala | Leg pain | ? |
| Samartzis and Marco (2006)18) | 11, M | S2 | Lamina | Leg pain | Good |
| Present study | 63, F | S1 | AP | Drop foot, numbness | Good |
AP: articular process, F: female, M: male.
As the neuroradiological examination tools, plain X-rays are insufficient in some cases, because of overlapping of osseous structures of the spine.16,17,19) The computed tomography (CT) scan is necessary, allowing radiologic diagnosis by showing cortical and medullary continuity between the tumor and the vertebra.17) At CT, all of our 5 cases contained honeycomb appearance or low density area in the central portion of the tumor. At MR imaging, the lesion manifests with a high intensity in the central area corresponding to the central cancellous bone in T2 -weighted image. Cartilaginous cap also displays high intensity in T2-weighted image.20) A chondroid tumor matrix in the cap may show increased signal intensity on T2-weightd images, but if the cap is thin or highly cellular, distinctive signal characteristics may be absent.21) Low signal intensity mineralization that serves as a boundary between the medullary space and a thin cartilaginous cap may be present, especially in children.1) With age, cartilage tends to thin and disappear at numerous points on the surface of an OC.22) In our 5 patients, cartilaginous cap, confirmed pathologically, could not be detected neither with CT nor MRI. However, all the tumors contained the central cancellous bone displaying high signal intensity on T2-weighted images (Figs. 1b, 2b, 3b).
References
- 1). Rodallec MH, Feydy A, Larousserie F, Anract P, Campagna R, Babinet A, Zins M, Drapé JL: Diagnostic imaging of solitary tumors of the spine: what to do and say. Radiographics 28: 1019– 1041, 2008. [DOI] [PubMed] [Google Scholar]
- 2). Albrecht S, Crutchfield JS, SeGall GK: On spinal osteochondromas. J Neurosurg 77: 247– 252, 1992. [DOI] [PubMed] [Google Scholar]
- 3). Dahlin DC, Unni KK: Bone Tumors. General Aspects and Data on 8,542 Cases, ed 4 Springfield, Charles C. Thomas, 1986, pp 228– 229 [Google Scholar]
- 4). Robbins SE, Laitt RD, Lewis T: Hereditary spinal osteochondromas in diaphyseal aclasia. Neuroradiology 38: 59– 61, 1996. [DOI] [PubMed] [Google Scholar]
- 5). Royster RM, Kujawa P, Dryer RF: Multilevel osteochondroma of the lumbar spine presenting as spinal stenosis. Spine 16: 992– 993, 1991. [DOI] [PubMed] [Google Scholar]
- 6). Fiumara E, Scarabino T, Guglielmi G, Bisceglia M, D'Angelo V: Osteochondroma of the L-5 vertebra: a rare cause of sciatic pain. Case report. J Neurosurg 91(2 Suppl): 219– 222, 1999. [DOI] [PubMed] [Google Scholar]
- 7). Ohtori S, Yamagata M, Hanaoka E, Suzuki H, Takahashi K, Sameda H, Moriya H: Osteochondroma in the lumbar spinal canal causing sciatic pain: report of two cases. J Orthop Sci 8: 112– 115, 2003. [DOI] [PubMed] [Google Scholar]
- 8). Bess RS, Robbin MR, Bohlman HH, Thompson GH: Spinal exostoses: analysis of twelve cases and review of the literature. Spine 30: 774– 780, 2005. [DOI] [PubMed] [Google Scholar]
- 9). Fiechtl JF, Masonis JL, Frick SL: Spinal osteochondroma presenting as atypical spinal curvature: a case report. Spine 28: E252– E255, 2003. [DOI] [PubMed] [Google Scholar]
- 10). Gürkanlar D, Aciduman A, Günaydin A, Koçak H, Celik N: Solitary intraspinal lumbar vertebral osteochondroma: a case report. J Clin Neurosci 11: 911– 913, 2004. [DOI] [PubMed] [Google Scholar]
- 11). Lotfinia I, Vahedi P, Tubbs RS, Ghavame M, Meshkini A: Neurological manifestations, imaging characteristics, and surgical outcome of intraspinal osteochondroma. J Neurosurg Spine 12: 474– 489, 2010. [DOI] [PubMed] [Google Scholar]
- 12). Urso S, Carfagni A, Amorese V: Vertebral compression syndrome in multiple exostoses (case report). Ital J Orthop Traumatol 3: 333– 340, 1977. [PubMed] [Google Scholar]
- 13). van der Sluis R, Gurr K, Joseph MG: Osteochondroma of the lumbar spine. An unusual cause of sciatica. Spine 17: 1519– 1521, 1992. [DOI] [PubMed] [Google Scholar]
- 14). Xu J, Xu CR, Wu H, Pan HL, Tian J: Osteochondroma in the lumbar intraspinal canal causing nerve root compression. Orthopedics 32: 133, 2009. [PubMed] [Google Scholar]
- 15). Sung HW, Shu WP, Wang HM, Yuai SY, Tsai YB: Surgical treatment of primary tumors of the sacrum. Clin Orthop Relat Res 91– 98, 1987. [PubMed] [Google Scholar]
- 16). Hanakita J, Suzuki T: Solitary sacral osteochondroma compressing the caudaequina—case report. Neurol Med Chir (Tokyo) 28: 1010– 1013, 1988. [DOI] [PubMed] [Google Scholar]
- 17). Agrawal A, Dwivedi SP, Joshi R, Gangane N: Osteochondroma of the sacrum with a correlative radiographic and histological evaluation. Pediatr Neurosurg 41: 46– 48, 2005. [DOI] [PubMed] [Google Scholar]
- 18). Samartzis D, Marco RA: Osteochondroma of the sacrum: a case report and review of the literature. Spine 31: E425– E429, 2006. [DOI] [PubMed] [Google Scholar]
- 19). Miyakoshi N, Hongo M, Kasukawa Y, Shimada Y: Cervical myelopathy caused by atlas osteochondroma and pseudoarthrosis between the osteochondroma and lamina of the axis: case report. Neurol Med Chir (Tokyo) 50: 346– 349, 2010. [DOI] [PubMed] [Google Scholar]
- 20). Bernard SA, Murphey MD, Flemming DJ, Kransdorf MJ: Improved differentiation of benign osteochondromas from secondary chondrosarcomas with standardized measurement of cartilage cap at CT and MR imaging. Radiology 255: 857– 865, 2010. [DOI] [PubMed] [Google Scholar]
- 21). Quirini GE, Meyer JR, Herman M, Russell EJ: Osteochondroma of the thoracic spine: an unusual cause of spinal cord compression. AJNR Am J Neuroradiol 17: 961– 964, 1996. [PMC free article] [PubMed] [Google Scholar]
- 22). Gille O, Pointillart V, Vital JM: Course of spinal solitary osteochondromas. Spine 30: E13– E19, 2005. [PubMed] [Google Scholar]