Multiple osteochondromas of the cervical spine, a potential cause of radiculopathy in the elderly: A case report and review of literature

Highlights • Osteochondroma is the most common type of bone tumor.• It rarely arises on the cervical spine.• It rarely occurs in the elderly.• Although rare, it may be considered as a differential diagnosis of radiculopathy among the elderly.


Introduction
Osteochondroma is the most prevalent benign bone tumour, characterized by an osteocartilaginous cap and bone marrow tissue continuous to the underlying bone [1]. This lesion accounts for 10% of all bone neoplasm and 35% of benign bone lesions. It is commonly found on the appendicular skeleton, but it may rarely present on axial skeleton including on the spine [2].
Spinal osteochondroma frequently occurs in the third decade of life and rarely affects the elderly. The most common predilection of this benign neoplasm is on the cervical spine, followed by lumbar, thoracic, sacrum, and coccyx; it most commonly affects the posterior column of the spine [3,4].
We present an unusual case of symptomatic multiple osteochondromas in an elderly patient arising from the posterior arch of C1 and lamina of C2. This work is reported in line with SCARE 2018 criteria [5].

Case report
A 76-year old female presented to the authors' hospital outpatient clinic with pain and numbness of the left suboccipital and preauricular region which persisted for the last six months. There was hypoesthesia of the left C2 and C3 dermatome; there were no signs or symptoms of myelopathy (spinal cord compression). The patient's past medical and familial history was not remarkable; she never had any previous surgery, and she was not on any medication. The patient's JOA (Japanese Orthopaedic Association) score was 16 out of 17 (normal function) [6].
Plain radiographs showed no abnormality.  Laboratory examinations did not show any abnormality. Based on the clinical features and pathological radiological findings, the authors suggested that the lesion most likely could be an osseocartilaginous benign tumor or known as osteochondroma.
The authors decided to perform decompression through excision of the lesion. The lesion was explored through posterior approach, exposing level of C1 and C2. As C1 lateral mass was preserved, posterior arch osteotomy of C1 was performed. The osteochondral lesion of left lamina C2 was removed by left hemilaminectomy. The lesion excised is depicted in Fig. 4.
Diagnosis of osteochondroma was verified histopathologically. The patient could mobilize on the next day. There was no postoperative wound complication found. The clinical follow-up was performed up to seven days after surgery. The neck pain decreased, and the hypoesthesia of C2-C3 dermatome was significantly improved.
Radiologic follow-up by MRI after six months showed no sign of recurrence (Fig. 5). The latest clinical follow-up was 18 months after the operation. The patient was ambulatory, but she complained of mild fingers numbness and moderate neck pain.

Discussion
Osteochondroma is the most common benign lesion of the bone. It may be multiple or solitary; the former is caused by mutation of exostosin-1 (EXT1) and exostosin-2 (EXT2) [7]. The later can sometimes be caused by a mutation in EXT1 gene, but the exact etiology of this solitary form is still debated [8].
The majority of osteochondroma arises in the metaphyseal region of long bone [9]. It may also arise in the axial skeleton including the spine, in which the most common site affected is on the cervical part. Lotfinia et al. stated that the most common location affected is the C1 vertebrae, contrary to the previous finding which concluded C2 was the most common site [10]. In this patient, there were multiple osteochondromas involving both C1 and C2 vertebrae. The incidence of this lesion peaks during the third decade of life and usually cease to grow with the closure of growth plate during the adolescent [11]. Thus, this lesion is rarely observed in the elderly such as in this case. Some previous case reports suggest that the development of this lesion may continue beyond skeletal maturity, and it may be affected by other disease progression such as psoriatic arthritis [4].
About 29.5% of all osteochondroma of the spine would cause radiculopathy and about 27% would cause myelopathy. Moreover, the tumor growth may present as a progressive symptom not unlike degenerative changes of spinal stenosis [3]. In the present case, the patient presented with radiculopathy of C1-C2 without any myelopathy.
Other benign tumors of the spine which may occur in older patients includes neurofibroma and giant cell tumor (GCT) [12]. The gradual progression of patients' symptom may reflect other causes of radiculopathy in the geriatrics, such as ossified posterior longitudinal ligament (OPLL), which is quite common in East Asian population and often affecting the cervical spine [13].
The imaging of spinal osteochondroma usually involves multiple modalities. Conventional plain radiograph is of low diagnostic value, especially for small lesion which is often obscured by adjacent structures [14]. Likewise, in the present case, conventional radiograph didn't show any abnormality.
Computed tomography (CT) is the gold standard given the lesion's major osseous component. CT could define its exact location and its connection to the central canal and neural foramen. On MRI, the cortex would be low intensity in any sequence. The marrow would show high intensity in T1 and intermediate intensity in T2. On the other hand, the cartilage cap would show variable intensity according to its degree of calcification [14].
The treatment of this lesion usually involves the en bloc resection from the posterior approach (80.5%) due to its location propensity [3]. In this case, the authors also performed an excision through posterior approach. The posterior arch osteotomy and the laminectomy of C2 improved the patient's symptom of suboccipital pain one day after the procedure.
Symptoms duration and characteristics are variable. The shortest presentation was two months, ranging up to ten years. Most cases presented as radiculopathy or myelopathy. There are three unusual presentations of vertigo, obstructive sleep apnea, and dysphagia [21,23,24]. Seven cases were successfully treated without    any remaining symptoms or recurrences. Two cases had remaining neurologic symptoms; one case was not treated surgically, but no further growth was observed during follow-up. One case didn't report the follow-up.

Conclusion
Osteochondroma of the cervical spine is quite rare, especially in elderly patients. However, this diagnosis could be considered as a cause of progressive radiculopathy in the elderly. Precise diagnosis through careful history taking, physical examination, and multimodal radiologic examinations should be made to solve this problem.

Declaration of Competing Interest
All authors declare that there is no conflict of interest regarding this study.

Funding
This study is solely funded by the authors.

Ethical approval
This study has been reviewed by the authors' Institutional Review Board, and the patient had given a written consent.

Consent
The patient had given a written consent. All identifying details have been omiited from the manuscript.

Registration of research studies
This case report is not registered.

Provenance and peer review
Not commissioned, externally peer-reviewed.