Locally aggressive monostotic fibrous dysplasia of the cervical spine mimicking malignancy: a case report and literature review

We report the case of a 30-year-old woman with histologically proven monostotic fibrous dysplasia of C2 revealed by a pathological fracture of the odontoid process. Radiological investigations showed a ground-glass mineralization of the vertebral body, a centimetric lytic area with poorly defined margins involving the inferior part of the vertebral body and inferior endplate and a fracture through an osteolytic area in the base of the odontoid process. Owing to the vertebral instability, a surgical procedure combining C0-C5 fixation and posterior bone grafting was performed. The surgical biopsy was inconclusive and pathological confirmation was finally obtained through a percutaneous needle biopsy under fluoroscopic guidance. At 26-month follow-up, the patient still experienced mild persistent cervical posterior neck pain and stiffness possibly related to a C5-6 laxity below the intervertebral fixation. This case combines three radiological findings, which are unusual in fibrous dysplasia: monostotic presentation involving the spine, some aggressive radiographic features, and a pathological fracture.