Study Design Case report and review of the literature.

Objective A retro-odontoid mass is a rare cause of cervical compression and myelopathy. The differential diagnosis includes the following: metastatic disease, primary tumor, collagen disorder, or inflammatory disease. Calcium pyrophosphate dihydrate (CPPD) deposition has been referred to as “crowned dens syndrome” when there are periodontoideal calcifications. There are only a few reported cases where CPPD presents as a cystic retro-odontoid mass in the atlanto-dens interval. In previous descriptions of surgical intervention, transoral resection of the mass is associated with significant morbidity and usually requires stabilization. The objective of this article is to report a case of an unusual presentation of CPPD disease of C1/C2, where we used a novel, minimally invasive surgical technique for decompression without fusion.

Patients and Methods An 83-year-old female patient presented with progressive cervical myelopathy over a 3-month period. Computed tomography and magnetic resonance imaging demonstrated a cystic odontoid mass with a separate retro-odontoid compressive mass. A novel, minimally invasive transoral aspiration was performed. Histologic confirmation of CPPD was obtained.

Results Postop imaging showed satisfactory decompression, which was maintained at the 6-month follow-up. This correlated with clinical improvement postop and 6-month follow-up.

Conclusion CPPD in the atlanto-dens interval may present as a cystic retro-odontoideal mass and should be included in the differential. We used a transoral minimally invasive approach to aspirate the cyst. This novel technique avoided the need for a stabilization procedure or morbid transoral resection and provided excellent results immediately and at 6 months.