Introduction

Osteochondromas constitute 0–15% of all bone tumors and 20–50% of all benign bone tumors [1]. Between 1.3 and 4.1% of solitary osteochondromas arise in the spine [2]. In spine, they have special predilection for the posterior elements of cervical or thoracic spine. They are usually asymptomatic, and compressive myelopathy is a rare presentation [3].

Case report

We report a case of a 16-year-old boy who presented with a history of weakness on the left side of his body with duration of 30 days which progressed to the right side for 10 days. He was able to stand and all kith support. There was also history of difficulty in holding things with both hands (left> right).

On examination, higher mental function and cranial nerve examination were normal. Fundi were normal. Tone was increased in all four limbs. Power on the left upper and lower limbs was 2/5 and on the right upper and lower limbs was 3/5. Deep tendon reflexes were brisk all over, and plantars showed bilateral extensor response. There was gross impairment of spinothalamic tract and posterior column sensations in all the limbs. Magnetic resonance imaging of the spine revealed an extradural mass lesion (Figs. 1 and 2) arising from the posterior arch of C3 vertebra leading to cord compression. Plain computed tomography of the cervical spine revealed a C3 posterior arch bony lesion projecting into spinal canal. (Figs. 3 and 4).

Fig. 1
figure 1

MRI spine (T2-weighted sagittal view): extradural mass lesion arising from the posterior arch of C3 vertebra leading to cord compression

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Fig. 2
figure 2

MRI spine (T2-weighted axial view): extradural mass lesion arising from the posterior arch of C3 vertebra leading to cord compression

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Fig. 3
figure 3

CT spine (sagittal): C3 posterior arch bony lesion projecting into spinal canal

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Fig. 4
figure 4

CT spine (axial): C3 posterior arch bony lesion projecting into spinal canal

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A vertical midline incision was made from C2 to C4 spinous process. Total excision of the tumor was carried out along with lamina of C3 vertebra. The histopathological examination was diagnostic of osteochondroma (Fig. 5). By the 2nd postoperative day, the patient had significant improvement and at the end of the 10th day of surgery, the patient had normal power in all the four limbs. There has been no recurrence at follow-up after 18 months.

Fig. 5
figure 5

Photomicrograph shows cartilaginous capsule with underlying mature bone trabeculae with interphase of enchondral ossification. ×40 (hematoxylin and eosin)

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Discussion

Osteochondromas are thought to arise through a process of progressive enchondral ossification of aberrant cartilage of the growth plate as a consequence of a congenital defect or trauma. The secondary ossification centers, which lie in the spinous process, transverse process, articular process, and end plate of the vertebral body fuse in adolescence, which completes the growth of vertebral column. The secondary ossification centers appear between the ages of 11 and 18 years in the cervicothoracic and lumbar spine, respectively, and in the sacrum during the 3rd decade of life. The more rapid the ossification processes of these centers, the greater the probability that aberrant cartilage will form. This explains the fact that osteochondromas are more frequently located in the higher segments of the vertebral column [2, 3].

Osteochondromas present as sessile or pedunculated bony lesions with periosteum and cortex that are continuous with those of the host bone. They manifest in two different patterns, solitary lesions with no genetic abnormality or as multiple lesions known as hereditary multiple exostoses. The long bones of the lower extremity are most frequently affected (50% of cases) and are more commonly involved than those of the upper extremity by a ratio of 2 to 1. Spinal involvement is unusual (2%) [1].

According to the study reported by Albrecht et al. [3], 49% of the osteochondromas which develop in the vertebrae occur in the cervical vertebra, 26% in the thoracic vertebra, and 23% in the lumbar vertebra. Osteochondromas are more common in males than females, with a male to female ratio of about 1.5:1.4. The mean age of most patients is 20 years or younger [3–5]. Our reported patient is 16 years old. Osteochondromas commonly arise from the tip of the spinous process and project outwards [6]; however, in our case, it arose from the inner surface of lamina and projected inside causing cord compression.

The clinical manifestations vary widely. The tumor may present as painful sites or as palpable masses that may or may not be painful. Neurological signs are exhibited when the lesion involves the spinal canal and these tumors may cause radiculopathy or myelopathy. It is the result of progressive encroachment of the slowly expanding osteochondroma on neural structures. Our case presented with feature of compressive myelopathy. Nevertheless, association with neurological symptoms is very rare because most lesions do not invade the spinal canal [7].

The detection of spinal osteochondroma may be difficult on plain radiography because of the many superimposed structures found on various projections [8]. Characteristic findings on CT scan are paraspinal, dumbbell, or eccentrically located, round, and sharply outlined mass in the spinal canal with bone-like density with scattered calcifications and osteosclerotic changes in the neighboring bone and lacking contrast enhancement [9]. CT scan of the cervical spine in our case exhibited a lobulated osseous mass with sclerotic margin that projected from the inner aspect of the left-sided lamina of C3 into the spinal canal. MRI is useful in demonstrating the level and extent of neural compression along with the marrow content and the cartilaginous cap, which gives the appearance of a prominent peripheral rim of low intensity corresponding to ossification and a small central core of intermediate signal similar to that of bone marrow. MRI of our patient showed a pedunculated bony lesion, arising from the left lamina of C3 vertebra showing direct medullary continuity, with a smooth overlying T2 hyperintense covering suggestive of cartilaginous cap. The lesion is seen to grow into the spinal canal and displace the cord to right side with cord compression.

On reviewing the literature, we found nine cases of cervical osteochondroma in the pediatric age group presenting with cord compression (<18 years; Table 1).

Table 1 Literature review of cases of pediatric cervical osteochondroma presenting with spinal cord compression
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Asymptomatic presentation of solitary osteochondromas can be managed conservatively due to the low rate of malignant transformation [19]. Tumor causing pain or neurological complication due to compression or the ones with indefinite diagnosis should be excised at base. Complete excision is the goal because incomplete removal of cartilaginous cap may lead to tumor recurrence [20]. Our patient presented with symptoms of cervical myelopathy which was progressive in nature. Complete excision of the lesion with partial C3 laminectomy was done to relieve the compression and prevent recurrence.

Spinal osteochondromas must be remembered as rare etiology of the spinal cord or root compression in the pediatric age group, and utmost care should be taken while excising these benign lesions.