Key-words:
Osteoid osteoma body of vertebrae - scoliosis - thoracic spine
Introduction
Osteoid osteoma (OO) affecting the spine is one of the common causes of painful scoliosis
in the growing age group.[[1]] The majority of them are located in the posterior elements of the vertebrae and
affection of the body of the vertebrae is rare. In the vertebral region, the lumbar
and cervical spine are commonly affected and the thoracic location is also sparse
accounting for about 10%.[[2]],[[3]],[[4]] As such, the diagnosis can easily be missed on simple X-rays if the pain is not
severe enough to warrant further investigations.[[5]] Here, we describe an OO affection the body of a thoracic spinal vertebrae causing
painful scoliosis in a teenager and discuss the diagnostic and management challenges.
Case Report
A 15-year-old male presented with diffuse pain for 9 months in the thoracolumbar spine
with nocturnal exacerbations that was relieved with painkillers. He was neurologically
intact. Plain X-ray revealed a left thoracolumbar scoliosis with a Cobb's angle of
30° [[Figure 1]]. A computerized tomography (CT) showed a lucent area in the right posterolateral
corner (zone IVA) of the dorsal vertebral body (<2 cm) with central dense focus –
nidus suggestive of OO [[Figure 1]]. Sagittal and axial T2 magnetic resonance images showed edema in the region with
reactive sclerosis seen on CT without any associated anomalies [[Figure 1]]. With the clinical and radiological diagnosis of OO, the parents were counseled
for the surgery. Through a midline posterior approach, a right of D12-L1 hemilaminectomy
and facetectomy was contemplated after securing pedicle screws of D11, L1, and left-sided
D12 and the lesion was curetted and burred under fluoroscopic guidance [[Figure 2]]. A mesh cage with bone graft was placed in the void created and rods were fixed
[[Figure 2]]. Postoperatively, the patient was relieved of his diffuse pain and night cries.
Histopathological examination showed fragments of bony trabeculae with one of the
fragments showing central nidus and surrounding sclerosis suggestive of an OO [[Figure 3]]. Repeat CT scan confirmed the excision of the lesion [[Figure 2]]. At 6 months follow-up, the patient is doing and now lives an active, unconstrained
life.
Figure 1: Clinical picture demonstrating left-sided scoliosis in a young patient (a and b).
Posteroanterior and lateral radiographs of the same patent shows S-shaped scoliosis
with concavity toward the right (yellow arrow). No lesion could be appreciated on
the radiographs (c). Reformatted sagittal and coronal computed tomography image demonstrating
a lucent area in the posterolateral corner of the dorsal vertebral body (white arrow)
with central dense focus - nidus (d and e). Sagittal and axial T2 magnetic resonance
image show edema (red arrow) in the region of the lesion seen on computed tomography
(f and g)
Figure 2: Intraoperative fluoroscopy images showing curette and cage placement (a and b). Postoperative
posteroanterior and lateral radiographs showing a slight improvement in the alignment
of the spinal curvature with implants in place (c). Postoperative reformatted coronal
and sagittal computed tomography images (red arrows) confirming the excision of the
lesion (d and e)
Figure 3: Low power photomicrograph of the lesion showing a central nidus surrounded by bony
trabeculae, H and E stain, xioo (a). High power view of the central nidus showing
woven bone with osteoblastic and fibroblastic proliferation, H and E Stain, ˣ400 (b)
Discussion
OO presents in the adolescence as benign primary osteoid producing tumor of the bone
characterized by small size, limited growth, and disproportionate pain.[[2]],[[6]] It affects the spine in 7%–20% of cases.[[1]],[[5]] Although it manifests as painful scoliosis, yet the disease could be a painless
condition. The diagnosis is very likely to be missed on a plain radiograph if one
is not oriented due to their small size and complex anatomy of the spine.[[5]],[[7]] A complete radiographic evaluation for scoliosis is necessary before stamping as
adolescence idiopathic scoliosis, including a CT scan and magnetic resonance imaging
(MRI).[[8]]
Most studies have found posterior elements, namely, the neural arches to be affected
(33% involved lamina, 20% involve articular facets, and 15% involve pedicles) with
rarely (7%) involvement of the vertebral bodies.[[3]],[[4]],[[9]],[[10]],[[11]]
Despite innovations in diagnostic expertise, there is a lag period average onset of
symptoms and establishing a diagnosis. People have found this could vary between a
year to 5 years or even more.[[5]],[[12]] On top of it, there is a 54% chance of a misdiagnosis.[[13]] The classic MRI findings include calcification within the nidus enclosed by sclerosis
which appears as low signal intensity on T1- and T2-weighted images and enhancement
of the nidus contrast. Bone scan (Scintigraphy using technetium-99 m) has proven to
be more specific for the diagnosis of small lesions particularly with spinal involvement.[[14]] The differential diagnosis comprises osteoblastoma, aneurysmal bone cyst, giant
cell tumor, and osteomyelitis.[[15]] Malignant tumors are rare in children and adolescents. These can be differentiated
with their characteristic clinical, imaging, and histopathological features.[[15]]
Spinal OO needs surgical treatment in the form of curettage.[[2]],[[10]] Sapkas et al. and Zhang et al. did and excision and stabilization in their respective
cases due to the creation of iatrogenic instability in their respective cases.[[3]],[[5]] Sasani et al. could simply excise an OO involving the D8 body that also involved
the pedicle.[[11]] However, sometimes the OO is deep, and reaching to it creates a void as in our
case, then a bone graft for structural support is needed to prevent further kyphosis
reinforced with added instrumentation. Ransford et al. suggest that early surgery
is recommended for the complete resolution of scoliosis.[[16]] Sasani et al. did a Rosenthal et al. introduced the image-guided radiofrequency
ablation for treatment of OO that has been extrapolated to be used successfully in
the spine Wang et al.[[17]],[[18]] The facility is sophisticated and sparse in many places where surgery offers a
cheaper and complete removal. Recurrence is a known but rare complication.[[5]]
Conclusion
OO affecting the body of the spine rare cause of scoliosis. It may be painless but
needs to be differentiated from the adolescent idiopathic scoliosis to prevent misdiagnosis
as surgical management is different in both of them.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms.
In the form, the legal guardian has given his consent for images and other clinical
information to be reported in the journal. The guardian understands that names and
initials will not be published and due efforts will be made to conceal identity, but
anonymity cannot be guaranteed.
