A Rare Case of an Osteoid Osteoma of the Cervical Spine

Osteoid osteoma (OO), a rare bone-producing tumor, can occur anywhere in the skeleton, [1, 2] and in the spine it is frequently located in the posterior elements involving the lamina, pedicles, or the transverse and spinous processes [3, 4]. Very rarely, OO develops in the cervical spine [1], being more common in children and young patients, with 90% of the patients being aged between 5 and 25 years [5].

The early diagnosis of OO is difficult, given the deceptive symptoms and the young age of most patients, postponing complementary studies [6-8]. The first symptom is generally pain, with patients’ reporting a moderate intermittent pain near the tumor that is more severe at night. In the early stages of the disease, patients feel a temporary pain relief with nonsteroidal anti-inflammatory drugs (NSAIDS). However, cervical pain worsens becoming no longer responsive to analgesics.

Plain X-ray is usually the first imaging choice [5]. However, it is not very informative when the OO is located in the cervical spine because of the tumor’s small size and the complex anatomy of its setting. Computed tomography (CT) successfully diagnoses 20–30% of the small osteolytic lesions with dense sclerotic rings and central calcifications. CT is a precise technique as it reveals the anatomical location of the nidus with an accuracy superior to that of magnetic resonance imaging (MRI) [5, 9]. Bone scan is also used in OO diagnosis, especially when the radiographic results are ambiguous or negative [10, 11]. However, the false-negative bone scans and reduced sensitivity for bone marrow disease confines bone scan use [12, 13].

CT-guided radiofrequency ablation (RFA) is considered the firstline therapy since the early 1990s [14]. In spite of its advantages over surgery and the facility to treat high-risk localizations (e.g., spine) [15-17] with a success rate ranging from 94 to 100%, RFA is only indicated for spinal OO lesions with no neurological deficits, intact cortical bone, and abundant cerebrospinal fluid around the lesion to prevent neurological damage by heat. Otherwise, surgery is the treatment of choice [1, 18, 19], provided the vertebral canal is not within the ablation zone, and the approach (anterior or posterior) to be used is selected according to the location of the tumors [20, 21].

If surgery is the treatment option, to avoid OO recurrence, complete surgical excision of the nidus is necessary. Quite often, this is difficult due to the risk of iatrogenic instability or neurological injury [22-24]. When complete resection of the tumor is not possible, many authors propose selective embolization and, for aggressive tumors, radiotherapy as adjuvant therapies [19, 22].

Herein we present a rare case of cervical OO, on the left lamina of C7, of a 16-year-old female patient, who underwent surgical treatment with complete resection by C7 laminectomy and cervical arthrodesis (C6-T1).

The OO diagnosis was obtained by physical examination of the patient in conjunction with X-ray followed by MRI, CT scan, and single-photon emission computed tomography (SPECT)-CT. The surgical excision of the lesion was performed using the posterior approach. The histological examination of the resection specimen was used to confirm the diagnosis.

A 16-year-old female patient presented to the outpatient clinic with cervical pain and torticollis, more intense on the left side. The symptoms started 1 year before, and worsened progressively. X-ray revealed a segmental inversion of the cervical lordosis at C6-T1; however, it was not possible to identify a corresponding bone lesion (Fig. 1). MRI showed a focal area with hyperintense signal in T2-weighted images and short tau inversion recovery, hypointense signal in T1-weighted images, and enhancement after contrast in the left vertebral body of C7 (Fig. 2). Subsequent bone scan revealed a focus of intense osteoblastic hyperactivity in the left lamina of the C7, compatible with the diagnosis of OO (Fig. 3). This lesion was confirmed and better defined on the CT scan and SPECT-CT (Fig. 4, 5). The patient’s age and the central location of the edema on the left lamina of C7, where it was possible to observe a sclerotic lesion with a peripheral ring and sclerotic lamina, also suggested an OO, as this type of tumor is usually round or ovoid, with a diameter <2 cm, a nidus and well-defined margins, and flexible adjacent osteosclerosis [25]. As symptoms were persistent, surgical treatment was offered. The surgical excision of the lesion was performed through a posterior approach. This technique allowed the execution of a laminectomy, followed by cervical arthrodesis (C6-T1), in order to avoid instability and iatrogenic kyphosis (Fig. 6). 12 months after surgical resection, the patient had no pain and scored 1% on the Neck Disability Index.

OO tumors are more frequent in children and young adults. Rarely, this type of tumor appears in the cervical spine and may evolve towards an osteoblastoma [26]. It is very difficult to diagnose an OO in the cervical spine because of its small size, the complex anatomy of the cervical spine, and the obfuscation by the overlying soft tissue [27]. Due to the small size of these tumors and their location, the diagnosis may be inaccurate, particularly if thin-slice CT-scan is not performed. It may take several months to get an accurate diagnosis after the first clinical symptoms [28, 29].Tumors of a small size are very difficult to detect by MRI as the nidus may be covered by the fibrovascular zone, reactive sclerosis, and the presence of edema in the bone [30-32]. As bone scan has a limited diagnostic specificity and reduced sensitivity for OO, false-negative cases have been reported [12, 13].

This study reports the case of a 16-year-old female patient with intense cervical spine pain, worst at night, which was partially relieved with ibuprofen. Even though X-ray revealed only a segmental inversion of the cervical lordosis, the hypothesis of a spine OO emerged as causative of the patient’s symptoms due to the painful and stiff spine deformity in a young patient and the fact that the patient’s pain was relieved by NSAIDS [33]. CT scan and MRI images identified a sclerotic lesion at C7, with surrounding edema of the adjacent tissues, compatible with an OO. Yet, although OO has particular characteristics on the CT, only the tumor’s histology provided a definitive diagnosis.

Although OO may have spontaneous resolution between 2 and 8 years after its initial symptoms, the frequent and severe pain and the risk of evolution to osteoblastoma [26, 34] prompted us to offer surgical resection as the treatment option for this patient. Although RFA is the first-line therapy with a success of 94%, its use is usually recommended when there are no neurological deficits, complete bone cortex around the lesion on CT, and abundant cerebrospinal fluid between the lesion and nerve root or spinal cord (>1.0 mm) to avoid neurologic injury by heat [35]. Following the patient’s careful examination, the option for surgical resection was taken considering the risk of surgical sequellae and the risk associated with RFA ablation due to the tumor’s localization and recurrence due to incomplete ablation.

En bloc tumor resection was performed by laminectomy. It was necessary to violate the facet joint with significant resection of the superior articular facet. As a significant portion of the articular facet was resected, a cervical arthrodesis (C6-T1) was performed to avoid instability and secondary neurologic injury [14]. This procedure allowed the maintenance of stability of the posterior spine, which was potentially compromised by the lesion of the facet joint. Moreover, this resection was performed in a transitional level with a high risk of post-laminectomy kyphosis.

The diagnosis was confirmed by the histological examination of the resection specimen (Fig. 7), and the patient’s follow-up revealed complete resolution of her long-standing cervical pain and disabilities 12 months after surgical excision of the OO.

Benign cervical spine bone-producing tumors are uncommon,but their presence should be considered in children, teenagers, and young adults with stiff spine deformity and persistent cervical pain worsening during the night and partially being relieved with NSAIDS. The diagnosis of OO requires a careful physical examination and appropriate imaging to ascertain the tumor characteristics and to consider different treatment options.

Although OO may regress spontaneously by unknown mechanisms, the persistence of pain and its long-term responsiveness to NSAIDS is an indication that the tumor should be removed. In the case reported, surgery was the treatment option to remove the cervical spine OO of a young female to avoid neurologic damage and incomplete tumor ablation. Complete resection of the lesion and resolution of the symptoms were achieved, and 12 months after tumor excision, the patient showed a good functional result.

The authors thank the parents of our patient and the patient herself for their support and permission to publish this report.

This manuscript complies with the guidelines for human studies and research and was conducted ethically in accordance with the World Medical Association Declaration of Helsinki. The patient’s parents and, very recently, the patient gave their written informed consent to publish this case including the images.

All authors declare that there are no financial and personal relationships with people or organizations that could inappropriately influence their work. Therefore, all authors declare there are no conflicts of interest to disclose.

Authors worked for Serviço de Ortopedia Pediátrica do Hospital Pediátrico, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal, which provided their corresponding salaries. No additional funding was given nor required since all expenses were supported by the Serviço de Ortopedia Pediátrica do Hospital Pediátrico.

F.S.G. was involved in the surgical intervention, collected the data, and wrote the first draft of the manuscript. C.A. reviewed the manuscript and the patient data, and critically reviewed and edited the drafts. P.C. and T.P.L. are members of the spine unit, and T.P.L. is the coordinator of the unit. Both were involved in the clinical evaluation of the patient, surgical planning, intervention, and follow-up.