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Univadis

Clinical Material and Methods

Sixteen patients with pathologically confirmed diagnoses of osteoid osteoma or osteoblastoma of the spine were surgically treated in our department over a 27-year period (1976–2003). On histopathological examination, any lesion with a diameter smaller than 2 cm was arbitrarily considered to be an osteoid osteoma, and one larger than 2 cm was diagnosed as an osteoblastoma. The original pathological reports confirming the diagnosis of osteoid osteoma and osteoblastoma were available in all cases. The neuroimaging findings assessed included the size and location of the lesion and the configuration and degree of sclerosis of its peripheral margin. By these criteria, five patients had an osteoid osteoma (two male and three female patients) and 11 (seven male and four female patients) had an osteoblastoma. There were nine male patients (two with osteoid osteoma and seven with osteoblastoma) and seven female patients (three with osteoid osteoma and four with osteoblastoma), showing a strong preponderance of osteoblastomas in male patients (Table 1 ).

The site of the tumor was the cervical (four patients), thoracic (six patients), and lumbar spine (six patients). In 14 patients, the tumor involved the posterior vertebral elements, with lumbar and thoracic levels the most common. Only two patients had tumor in the body of a cervical vertebra. The location of each type of tumor within the spine and within the VBs is given inTable 2 .

The mean age of the patients at the onset of symptoms was 20 years for osteoid osteoma and 19 years for osteoblastoma. The duration of symptoms prior to diagnosis was 1 to 60 months (mean 15.7 months). Symptom duration in patients with osteoid osteoma was 22 ± 14.9 months, and in patients with osteoblastoma it was 18.4 ± 16.1 months (mean ± standard deviation). The most common symptom was local pain in the area of the tumor. All patients reported continuous local pain, with only the five with osteoid osteoma noting an increase in pain at night. Eight patients reported increasing pain, with longer duration of symptoms. The descriptions of pain ranged from a dull throb to episodic sharp, stabbing pain to knifelike pain. Paravertebral muscle spasm and marked spinal stiffness were observed in 12 patients. Only one patient, who had an osteoblastoma in L-4 had scoliosis. Among the 11 patients with osteoblastoma, six experienced neurological deficits caused by extradural compression (two with paraparesis and four with monoparesis). None of the patients with osteoid osteoma had neurological deficits.

All patients underwent x-ray and CT studies; MR imaging was performed in six patients. Diagnosis based on neuroimaging findings was often difficult initially when lesions were small. The plain x-ray films aided diagnosis when lesions were located in the spinous process or transverse process. For lesions primarily involving the lamina, pedicle, or VB, the diagnosis could be made with the aid of CT and MR studies. The diameters of osteoblastomas were 3 to 8 cm (mean 4 cm), and osteoid osteomas were 1.5 to 2 cm (mean 1.7 cm) in diameter. Although the peritumoral bone was normal in patients with osteoblastoma, a sclerotic rim was observed in osteoid osteomas.

All patients underwent tumor resection. Fourteen patients were treated via a posterior approach with removal of the abnormal laminae, pedicle, transverse process, and facet joint. One patient with an osteoblastoma underwent a laminectomy and stabilization with posterior instrumentation. In another patient with an osteoblastoma invading the C-2 VB, the tumor was resected via a retropharyngeal anterolateral approach and the patient underwent a posterior occipitocervical stabilization and bone grafting. One patient with a C-5 VB osteoblastoma underwent corpectomy and bone fusion. Tumor excision was complete in 15 patients. Postoperative radiation therapy was delivered to the thoracic spine of a patient with T-10 osteoblastoma after incomplete removal of the tumor. None of the other patients received adjuvant therapy after surgery.

On histological examination osteoid osteoma consists of a small (< 1.5–2 cm), yellowish to red nidus of osteoid and woven bone with interconnected trabeculae, and a background and rim of highly vascularized, fibrous connective tissue. Varying degrees of sclerotic bone reaction may surround the lesion. Benign osteoblastoma is virtually indistinguishable from osteoid osteoma. The usual appearance included a fibrovascular stroma with numerous osteoblasts, osteoid tissue, well-formed woven bone, and giant cells. The osteoblasts were generally small and regular in shape. A typical case of osteoblastoma and its histological features is depicted in Figs. 1 and 2, and a case of osteoid osteoma and its histological features is depicted in Figs. 3 and 4.

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Case 8. Diagnostic images of C-2 osteoblastoma. This 10-year-old boy presented with neck pain, and on physical examination local swelling was found on right cervical region. Lateral x-ray films (a) showed a soft-tissue swelling in the retropharyngeal space. Lateral (b) and coronal (c) MR images demonstrating tumor in the C-2 body and a soft-tissue mass from C1–6. Axial CT scan (d) demonstrating a typical osteoid nidus with peritumoral sclerotic rim on the right side of the C-2 body. Technetium bone scan (e) also displays pronounced uptake in this region. We performed tumor excision via an anterolateral retropharyngeal approach (f) occipitocervical fixation by using two axis plates and titanium wires (g). Lateral x-ray films obtained immediately after (h) and 2 years postsurgery (i) showing solid fusion.

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Case 8. Histological studies of osteoblastoma.Upper: Photomicrograph showing packed, small, irregular trabeculae composed of pure woven bone and osteoid. A shell of ossification (arrows), (expanded and thinned cortex) is seen at the periphery of the osteoblastoma. Intertrabecular stroma is abundant and cellular.Lower: Photomicrograph showing that intense proliferation of cells occurs between irregularly serrated, thick woven bone trabeculae. The cells consist of osteoblasts (small arrows), osteoclasts (large arrows), and spindly stromal cells. This field also shows numerous dilated capillaries (C) and foci of hemorrhage (H). H & E, original magnifications × 40 (upper) and × 200 (lower).

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Case 14. Diagnostic images of C-5 osteoid osteoma. This 16-year-old man presented with neck pain only. Axial CT scan (left) revealing that a tumor arising from the left C-5 pedicle is compressing the left C-5 root. A technetium bone scan (center) displays high uptake of contrast material. Axial CT scan (right) demonstrating that left hemilaminectomy was sufficient to remove the tumor.

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Case 14. Histological studies of osteoid osteoma.Upper: Photomicrograph in which the nidus reveals contiguously joined trabeculae of well-calcified, woven bone at the left side. The thick bone trabeculae at right consist of host lamellar woven bone. The interface between the lesion and the surrounding host bone trabeculae is demarcated by a sheet of loose fibrovascular tissue.Lower: Photomicrograph showing a prominent single row of osteoblastic rim (white arrows), curved trabeculae of primitive woven bone (B), and a few osteoclasts (black arrows). The loose fibrovascular stroma is generally rich in thin-walled, dilated capillaries (C). H & E, original magnifications × 40 (upper) and × 400 (lower).

The results of surgery have been satisfactory in all cases, with follow-up periods ranging from 2 months to 13 years (mean 3 years). Complete pain relief was achieved in 15 patients; the remaining patient described mild pain with activity. There has been no tumor recurrence except in one patient with osteoblastoma.

There were two complications: in one patient with a T-6 osteoid osteoma, the initial surgical procedure was performed at the wrong level and a second operation was required to remove osteoid osteoma from the facet joint. In the other patient, a 14-year-old boy with T-5 osteoblastoma, a revision surgery was necessary because of instrument failure. This patient had undergone posterior fixation with a hook and rod system after tumor removal. Two years postsurgery the upper hooks on one side had loosened and the rod was dislocated, necessitating removal of the instrument. Repeated MR imaging demonstrated no recurrence of osteoblastoma.

Neurosurg Focus. 2003;15(5) © 2003  American Association of Neurological Surgeons

Cite this: Osteoid Osteomas and Osteoblastomas of the Spine - Medscape - Nov 01, 2003.