[Giant cell tumor of the C2 colonized by an aneurismal bone cyst. Report of case].

Giant cell tumor is colonized by aneurismal bone cyst in only 15% of cases and cervical localisation accounts for less than 1% of giant cell tumors. We are reporting a rare case of a C2 hypervascularized giant cell tumor colonized by an aneurismal bone cyst treated with an effective preoperative Onyx embolization followed by a full tumor resection. The patient experienced a moderate cervical spine injury 2 months prior admission followed by a progressive stiff neck and cervicalgia. CT and MRI identified a lytic lesion of the body and lateral masses of the C2 with encasement of both vertebral arteries. The angiography showed a hypervascularization of the lesion from the vertebral and external carotid arteries as well as a thrombosis of the V3 segment of the right vertebral artery at the C1 level. A posterior occipito-C3/C4 fixation and a tumor biopsy were performed. Histopathological examination concluded to a giant cell tumor colonized by an aneurismal bone cyst. Three weeks later, the patient developed a right upper extremity deficit. The MRI showed an increased C1-C2 stenosis and an increase of the hypervascularization. Three sessions of embolization by the onyx were performed. During surgery a near total tumor devascularisation was observed and a complete resection of the tumor was achieved through an anterolateral approach. Reconstruction consisted of a cementoplasty of the C2 body and odontoïd process with an anterior C3-prosthesis plate. The postoperative course was uneventful.