A rare case of "Brown tumor" of the axis with parathyroid adenoma and tertiary hyperparathyroidism

Abstract

"Brown tumors (BTs)" of the spine are benign rare lesions, seen in about 5%-13% of all patients with chronic hyperparathyroidism (HPT). They are not true neoplasms and are also known as osteitis fibrosa cystica or occasionally osteoclastoma. Radiological presentations are often misleading and may mimic other common lesions such as metastasis. A strong clinical suspicion is therefore necessary, especially in the background of chronic kidney disease with HPT and parathyroid adenoma. Surgical spinal fixation in case of instability due to pathological fracture may be required along with excision of the parathyroid adenoma being the treatment of choice, that maybe usually curative and carries a good prognosis. We would like to report one such rare case of BT involving the axis, or C2 vertebra, presenting with neck pain and weakness that was treated surgically. Only a few cases of spinal BTs have been reported so far in the literature. Involvement of cervical vertebrae and in particular C2 is rarer still with the one in this report only being the fourth such case.

Keywords: Brown tumor; C2 cervical vertebra; chronic kidney disease; hyperparathyroidism; myelopathy; parathyroid adenoma.

Figure 1

Graph showing laboratory biochemical data from the onset of detection to date

Figure 2

MRI of the cervical spine – T2WI (A: Sagittal, B: Axial, C: Coronal) showing an expansile lytic lesion involving the C2 vertebra, causing collapse with posterior impingement on the thecal sac and cord. MRI: Magnetic resonance imaging

Figure 3

CT of the cervical spine – (A: Sagittal, B: Axial, C: Coronal) showing an expansile lytic lesion (red arrows) involving the vertebral body, odontoid process, and left pedicle of C2 vertebra, causing collapse with posterior and left lateral subluxation; diffuse radiologic lucencies (osteopenia vs. multiple lytic lesions) in the other visualized bones including multiple vertebrae (blue arrows). CT: Computed tomography

Figure 4

H and E stained histopathology sections showing scanty fragments of viable and necrotic cortical bone with very scanty fragments of fascicles of spindle-shaped fibrous stromal cells with bland nuclear features and admixed few osteoclastic giant cells and foci of hemosiderin-laden macrophages and focal new bone formation; no evidence of cytologic atypia, mitosis or malignant chondroid, or osteoid; no evidence of malignancy or metastasis

Figure 5

Postoperative AP and lateral X-ray showing occipitocervical fusion with implants in situ. AP: Antero-Posterior