C4 cervical spine osteoblastoma associated with secondary aneurysmal bone cyst in an adolescent patient: 2-year follow-up.

Introduction: Osteoblastoma and aneurysmal bone cyst (ABC) are rare bone tumors with individual prevalence of <1%. Their combined occurrence is a rare subclass of tumors in the spinal column with only a few cases reported in literature. Case presentation: The present case is a rare combination of aggressive osteoblastoma with secondary aneurysmal bone cyst masquerading as neck pain, arising from cervical C4 vertebra in a 19-year-old male. The patient presented with complaints of neck pain for 7 months, gradual in onset, dull, aching, and progressively increasing in severity. Neurological examination was normal. Radiology showed an expansile lytic mass arising from the posterior elements of C4 vertebra involving the left lateral mass. Piecemeal total removal was done and a posterior fusion from C3 to C5 was performed for stability. Histopathology confirmed the osteoblastoma with a secondary aneurysmal bone cyst. Postoperatively the patient recovered well, and no recurrence was seen on a 2-year follow-up. Discussion: Simultaneous presence of an osteoblastoma with a secondary ABC arising from various bones, such as cranial fossa, ethmoid sinus, skull, and mandibular condyle, has rarely been reported. It is often diagnosed late due to nonspecific symptoms; but it has a good prognosis if early and complete resection is performed. Thorough surgical excision is always a challenge in spine cases due to surrounding important structures and meticulousness is required to prevent any recurrences. Hence, we recommend a surgical team comprising both spine and musculoskeletal oncologic surgeons to achieve best results. © International Spinal Cord Society 2019.