Abstract
Objective
Cervical spine osteochondromas are rare with approximately 3% of solitary and 7–9% of hereditary osteochondromas occurring in the spine. Almost 50% of spinal osteochondromas occur in the cervical region.
Methods
A search of osteochondroma of cervical spine was performed of our radiology database.
Results
In this study, we present 11 cases of adult cervical spine osteochondromas. These predominantly involved the posterior elements. The cartilage cap was more than 2 cm in 2 cases. There was cord compression in 1 case, foraminal narrowing in 2 patients and vertebral artery compression in 1 case. 6 patients underwent excision with majority being osteochondroma. There was only one case of chondrosarcoma.
Conclusion
Osteochondromas of cervical spine and extremely rare and symptomatology are due to mass effect. One should be aware of this entitly when analysing cervical spine for neck pain or lump.
Keywords: Cervical, Osteochondroma, Benign tumours
1. Introduction
Osteochondromas of the cervical spine are rare. They typically occur in the long bones of the body, and approximately 4% of all lesions occur in the spine.1,2 Most are asymptomatic, but the most common symptoms are a painless cosmetic deformity or a slowly enlarging exophytic mass. If large, there can be mass effect on the trachea or oesophagus.3 Neurological symptoms due to myleopathy or radiculopathy are seldom present as most lesions grow outside the spinal canal. Osteochondromas that are asymptomatic may not require treatment, however, lesions should be monitored for interval change.
Most cervical osteochondromas are solitary, but some are multiple and usually associated with the hereditary multiple exostoses (HME). The latter tends to have more serious implications for treatment when compared to solitary lesions. The risk of malignant transformation remains low (1–2% in solitary osteochondromas; 5–25% in the setting of HME).4
Most reported cases of cervical osteochondroma are seen at C2 followed by C3,C6 and usually involve the posterior elements.1 Although typically seen in children, the current literature only describes individual cases of paediatric and adult cervical spine osteochondromas. Various theories have been proposed to explain how osteochondromas can develop in children however, why they develop in the elderly population remains unknown. We present 11 cases of adult cervical spine osteochondromas, the largest series to our knowledge.
2. Methods
A retrospective review of the radiology information system at our institution was performed. Patients with cervical spine osteochondroma with cross sectional imaging of the lesion were identified. Clinical presentation, history of HME, subsequent treatment and follow-up were recorded, where available. Cross-sectional imaging was reviewed and the site and size of the osteochondroma and cartilage cap, neural foraminal narrowing, cord compression and local mass effect were also recorded.
3. Results
Cervical spine osteochondromas were identified in 11 patients with a mean age of 49.3 years (range 31–83 years, Male:female ratio of 5:6). Most osteochondromas were identified in the lower cervical spine, at C5, C6 and C7 (7 patients (63.6%), and all tumours involved a single level. 3 out of the 9 osteochondromas sited in the posterior elements were in the lamina. 2 cases were seen in the transverse processes and facet joints. Majority presented with neck pain (6). 2 cases had radicular symptoms and lump was the presenting symptom in 3 (Table 1).
Table 1.
Demographics, symptoms and management.
| Age At Event | Sex | Level | Symptoms | Management | histology |
|---|---|---|---|---|---|
| 83 | F | C7 | neck pain | left alone | |
| 33 | M | C7 | neck pain | left alone | |
| 54 | M | C7 | increasing lump | left alone | |
| 74 | F | C4 | myelopathy | excised | osteochondroma |
| 40 | F | C3 | neck pain | excised | chondrosarcoma |
| 34 | F | C3 | neck pain | excised | osteochondroma |
| 57 | F | C2 | Lump | left alone | |
| 17 | M | C6 | neck pain | excised | osteochondroma |
| 54 | F | C5 | neck pain and radiculopathy | excised | osteochondroma |
| 63 | M | C5 | neck pain | biopsy | osteochondroma |
| 31 | F | C5 | radiculopathy | excised | osteochondroma |
In our series, 6 cases were less than 3 cm and 5 cases were larger than 3 cm, with the largest osteochondroma measuring 6 cm. The mean size was 3.3 × 2.5 cm. 6 had excision, one underwent biopsy and 4 were left alone. There was only one chondrosarcoma in the cohort who had a recurrence 7 years post excision and had undergone a re-excision (Table 2).
Table 2.
Imaging finding.
| Age | Mean 49.3 (range 31–83) |
Site Anterior Posterior |
2 (18.2%)-vertebral body, 9 (81.8%) posterior elements-3 lamina, 2 transverse process, 2 facet joint, 1 spinous process, 1 pedicle |
| Level | Complications | ||
| C2 | 1 (9.1%) | Cord compression | 3 (27.3%) |
| C3 | 2 (18.2%) | Foraminal narrowing | 5 (45.5.%) |
| C4 | 1 (9.1%) | Mass effect | 0 |
| C5 | 3 (27.3%) | Vertebral artery | 5 (45.5%) |
| C6 | 1 (9.1%) | compression | |
| C7 |
3 (27.3%) |
Muscle oedema |
1 (9.1%) |
| Gender | Size | ||
| Male | 5 (45.5%) | Less than 30 mm | 6 (54.5%), smallest was 12 × 12mm |
| Female | 6 (54.5%) | More than 30 mm | 5 (45.5%), largest was 60 × 48mm |
| Average size |
33 × 25mm |
||
| Solitary | 9 (81.8%) | Management | |
| Multiple | 2 (18.2%) | Left alone | 4 (36.4%) |
| Biopsied | 1 (9.1%) | ||
| Excised |
6 (54.5%) |
||
| Cartilage cap | Mean 7.4 mm (range 0–30) |
4. Discussion
Osteochondromas arise due to a process of progressive enchondral ossification or aberrant cartilage of the growth plate. In vertebral bodies, the secondary ossification centres lie within the endplates, which fuse during adolescence. The secondary ossification centres appear at the approximate ages of 11 in the cervico-thoracic spine and 18 for the lumbar spine.5 The more rapid the ossification of these centres, the more likely aberrant cartilage can develop, explaining why osteochondromas are more frequent in the cervical spine. The cervical spine also suffers from more microtrauma than other parts of the vertebral column due to its increased mobility. This may displace epiphyseal cartilage, which can further stimulate growth.5
The mean age of reported osteochondromas is around 20 years for the hereditary type and 30 years in the solitary sub type.6 In our overall patient cohort mean age was 49 years. Although osteochondromas typically occur in young patients, those affecting the spine usually occur in the second to third decade of life. Sakai and co authors have suggested that degenerative changes in the vertebrae allowing the growth of aberrant cartilage may contribute to the development of osteochondromas in older patients.7 Interestingly, Yagi and co authors have reported 3 cases of cervical osteochondromas in the elderly who all had psoriatic arthritis.8 The underlying accelerated rate of bone metabolism caused by chronic inflammation from psoaritic arthritis may have led to abnormal osteochondroma enlargement in the elderly. These lesions may have been present during the adolescent years, stopped growing but then continued to grow later in life becoming symptomatic.9 A true link between an inflammatory arthropathy and development of osteochondroma remains to be established.
Cervical osteochondromas typically vary in size but can be up to 10 cm. In younger patients, the cartilage cap thickness is around 1–3 cm, and only a few millimetres in size for adults.10 For our older patient cohort group it was 7.4 mm with one patient having a cap thickness of 30 mm indicative of malignant transformation to chondrosarcoma (Fig. 4). It is important to note that the hyaline cartilage cap thickness also varies with skeletal maturity, increased cap thickness can be seen in young patients as a response to increased growth.10 Thus, cap thickness should not be used as an isolated finding of malignant transformation in skeletally immature patients.
Fig. 4.
Axial STIR (A) and CT (B) demonstrating a large osteochondroma with a large cartilage cap arising from the right articular process of C3, which was excised and histologically proven to be chondrosarcoma.
In our cohort, 7 out of 11 cases had osteochondromas within the lower cervical spine. This is in conflict with previous studies which reports C2 as the most commonly affected level, followed by C3 and C6.5 Furthermore, most lesions were seen in the lamina. Previously published data also describes the lamina as the most common location, followed by the pedicles, facets, spinous and transverse processes.10 The mean size of all the osteochondromas in our cohort was 3.3 × 2.5 cm. This is in concordance with most literature reporting an average size of 2–3 cm, however tumours as large as 7 cm have been decribed.11
The radiographic appearance of osteochondroma is a bony projection continuous with the cortex of the host bone. Morphologically, they are described as pedunculated if they present as a stalk like structure or sessile if there is no stalk. Although radiographs well demonstrate the sessile or pedunculated nature and continuity with the host bone, it typically fails to show the lesion in up to79% of cases.6 CT imaging can define the ossified cartilaginous components and demonstrate the relationship to the nearby vertebral and neural elements including the central canal and neural foramen. Typically, there is a bony mass with internal calcification and sclerotic changes in the adjacent bone.12 (Fig. 1, Fig. 2).
Fig. 1.
Axial CT (A), axial MRI (B) and sagittal MRI (C) demonstrating a large osteochondroma arising from the spinous process of C6 causing cord compression.
Fig. 2.
Axial CT (A and C) and axial MRI (B and D) of two different patients with large osteochondromas arising from C5 vertebral bodies causing marked left foraminal narrowing and left vertebral artery compression.
MRI shows the medullary and cortical components of the lesion, the latter having the same signal characteristics as the normal bone.12 (Fig. 1, Fig. 2) The central fatty marrow is hyperintense on T1 and T2 with a surrounding area of hypointense signal representing the cortex. MRI is ideal in quantifying any malignant transformation, whereby the cartilage cap is usually over 2 cm but can have varied appearances due to the amount or stages of mineralisation (non mineralised cartilage, calcified cartilage, and ossification with yellow marrow).12 Other signs of malignant transformation include invasive bony destruction, a soft tissue mass and increased osteolysis. Any nerve root or spinal cord compression can also be visualised on MRI (Fig. 1, Fig. 2). Adjacent paravertebral oedema has only been described in a few published cases and is usually seen with osteochondromas found in the posterior elements (Fig. 3). This could be related to denervation of muscles. Another cause for muscle and soft tissue oedema adjacent to an osteochondroma is due to fracture of the osteochondroma and CT is the best modality to identify this.
Fig. 3.
Sagittal STIR (A) and T2*(B) weighted MRI demonstrating a large osteochondroma arising from the right pedicle of C5 with marked oedema of the adjacent paravertebral muscles.
Due to the typical imaging appearances, there is a limited differential diagnosis for cervical osteochondroma however low grade chondrosarcoma does need to be excluded. Imaging can also play a role in assessing unusual presentation or complications of cervical osteochondroma including Horner’s syndrome, vertebral artery occlusion and rarely occipital nerve neuralgia.13
In our study, 5 patients showed imaging features of foraminal narrowing and 3 had signs of cord compression. In general, cord compression tends to be rare as most lesions grow out of the spinal canal. However, an increased incidence of spinal cord compression has been reported in HME cases when compared with solitary osteochondromas.14 The reported incidence of myelopathy or radiculopathy caused by the tumour is 0.5–1%.15 Osteochondromas arising from the anterior cervical vertebral body can compress surrounding tissues giving symptoms of dysphagia, sleep apnoea and respiratory distress although these are rare.10,16
Asymptomatic lesions are normally followed up with imaging. Solitary asymptomatic cervical osteochondromas can be managed conservatively due to the low rate of malignant transformation. However, symptomatic or indeterminate lesions should be excised at the base. The aim is complete excision given that incomplete removal of the cartilaginous cap can lead to tumour recurrence.14 Most spinal osteochondromas presenting with cord compression are treated with laminectomy or hemi-laminectomy owing to their posterior origin. Most operations include insitu marginal or wide excision with or without instrumentation.14 Standard surgical procedures are usually sufficient and the approach mainly depends on the location and relationship to nearby neurovascular structures.
The overall recurrence after resection is very low at 2%.9 Treatment of HME patients is much more problematic, and surgery is normally directed at fixing associated deformities rather than just the bony exostoses. Malignant transformation of osteochondroma to chondrosarcoma is generally treated with wide surgical resection, chemo/radiotherapy is not typically used.9
5. Conclusion
We present the largest, single-centre series of adult cervical spine osteochondromas to our knowledge. These have a predilection for posterior elements and neck pain is the most common presenting symptom in our series. Although uncommon, radiologists and clinicians should be aware of the spectrum of clinical and radiological features of these lesions and their potential complications.
Funding
No financial disclosures.
Declaration of competing interest
The authors declare that there are no conflicts of interest regarding publication of this paper.
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