PMC3038875_01
Technetium bone scan, MRI and CT. A; Technetium bone scan was useful in localizing the lesion. B, C; MRI revealed an intramedullary lesion, with isointense low signal on T1-weighted images and isointense high signal on T2-weighted images. D; Intense reactive sclerosis surrounding the nidus was seen on CT images.
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F1
Radionuclide bone scan, which revealed increased uptake of isotope in the S1 lamina on the left side, was useful in localizing the lesion (Figure 1A). C). The lesion was enhanced by gadolinium (Gd-DTPA). Computed tomography (CT) demonstrated intense reactive sclerosis surrounding the nidus (Figure 1D).
Histological feature of the nidus (x40). H.E. staining of the lesion revealed that the nidus included anastomosing trabeculae of osteoid and woven bone.
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F2
These findings yielded the pathologic diagnosis of osteoid osteoma (Figure 2).
PMC3038875_02
Conventional roentgenogram, CT and Gd-enhanced MR images. A; Anteroposterior radiograph of the thoracic spine revealed no abnormalities. B: CT revealed marked perilesional sclerosis of bone in the right facet. C, D, and E: Gd-enhanced area extended over the intervertebral foramen and the nerve root.
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F3
Anteroposterior radiographs of the thoracic spine revealed few distinct abnormalities in the thoracic spine (Figure 3A). T2-weighted images that was enhanced by Gd-DTPA was present over the T10 nerve root (Figure 3C-E). These MRI findings indicated inflammation and consequent edema. In contrast to MRI, CT revealed intense reactive sclerosis surrounding the nidus in the tip of the superior articular process of T11 (Figure 3B), with no compression of the nerve root on axial view.
Histological feature of the soft tissue around the nerve root. Photomicrograph of the soft tissue around the nerve root showing infiltration by chronic inflammatory cells including lymphocytes and plasma cells.
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F4
Some pieces of soft tissue around the facet joint and nerve root were taken for pathologic examination, which confirmed the diagnosis of osteoid osteoma and revealed the presence of chronic inflammation in the soft tissue around the nerve root (Figure 4).