An osteoblastoma is a vascular, osteoid, bone-forming lesion located mostly in the long bones and posterior elements of the spine. Corpus involvement is rare and extension is usually through the pedicles. Isolated corpus osteoblastomas are very rare.
Only two cases of osteoblastomas of the C2 corpus have been reported [7,8
]. Two other reports of osteoblastomas of the C2 odontoid process have been reported, and a histologically-similar lesion (osteoid osteoma) has also been reported to occur in the C2 corpus in several case reports [5,6,9
In the case reported by Camitta et al. [8
], the surgical excision was incomplete, which inevitably led to a recurrence. The recurrent lesion was treated with chemotherapy consisting of methotrexate, doxorubicin, and cisplatin.
Local recurrences have been reported in 9.8% to 15% in other series of spinal osteoblastomas [3,4,7
]. The main reason for this high rate of recurrence has been as attributed to incomplete resections. To avoid recurrences, meticulous and safe tumor curettage should be the primary goal of surgery. Considering the highly vascular nature of osteoblastomas, some authors have recommended pre-operative embolization to enhance visualization, while other authors obtain multiple biopsies to determine the exact extension of the tumor [2,5
]. Another characteristic of osteoblastomas that can impair complete resection is the frequent association of epidural invasion with osteoblastomas, which causes a higher incidence of torticollis with cervical lesions, as reported by Raskas et al. [10
]. Our case also had torticollis and epidural invasion was present, but we did not perform pre-operative embolization or obtain biopsies to determine the extent of the tumor. We suggest that visualization of the intraoperative surgical field is a determining factor for complete resection and the choice of surgical route is thus important.
We used an upward extension of the classical anterior cervical route for accessing the body of C2. This approach provided us with good surgical visualization and we achieved a complete resection. The transoral route is another way to reach C2, has been used by many authors, and has been reported to provide a good and safe approach to C1-C2 in experienced hands [5,9
Osteoblastomas can be locally aggressive with a high tendency for recurrence and metastasis. Osteoblastomas can even undergo malignant transformation to osteosarcomas, although this is rare [3,8,9
]. Radiotherapy and chemotherapy can be used for osteoblastomas, but the potential risk of post-radiation sarcomas must be kept in mind.