Isolated osteoradionecrosis of the dens mimicking metastasis of nasopharyngeal carcinoma after radiotherapy.

Nasopharyngeal carcinoma (NPC) is common in southern China, and radiotherapy remains the mainstay of treatment. A rare late complication of this treatment is the development of osteoradionecrosis (ORN), which seldom involves the cervical spine. We describe a 47-year-old female with undifferentiated carcinoma of the nasopharynx, stage II (T2N0M0), who had undergone radiotherapy 51 months prior, and complained of a twitching headache on neck flexion/extension. Imaging studies, including MRI and 18-fluoro-2-deoxyglucose positron emission tomography scan, suggested the diagnosis of cervical spinal metastasis. However, plasma Epstein-Barr virus DNA was undetectable, favoring absence of tumor recurrence. The patient underwent atlantoaxial sublaminar wiring for an unstable spine and a subsequent transoral biopsy, the histopathologic diagnosis of ORN. The postoperative clinical course was uneventful and follow-up MRI, 2 years later, revealed gradual resolution of the lesion. To our knowledge this is the first report of an isolated ORN lesion of the dens confirmed surgically in a patient with a history of previously treated NPC, a lesion at the cervical spine, and inconclusive imaging and biological marker results. We recommend that ORN be suspected until proven otherwise in a previously irradiated patient.