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

"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.