[Osteoid Osteoma in S2: Percutaneous CT Guided Resection of a Double Nidus]

The case report describes the option of percutaneous CT-guided ablation of osteoid osteoma with a double nidus to combine minimally invasive approach and CT(O-arm)-guided technique. Following X-ray, CT and MRI examinations, osteoid osteoma was diagnosed in the body of the second sacral vertebra (S2) in a 31-year-old female patient. CT reconstructions detected a double nidus with a defective, sclerotic rim. MRI demonstrated reaction in the surrounding tissue and edema in the nerve root. In consideration of the anatomic location of the osteoid osteoma and vicinity of the irritated S2 root percutaneous CT-guided intralesional resection of a double nidus was performed. There was immediate pain relief after the surgery, and the patient was discharged on the second postoperative day. The follow-up histological examination confirmed the diagnosis. During a five-year follow-up, the patient remained symptom-free and without recurrence of the disease. CT-guided minimally invasive resection of osteoid osteoma is an option in cases of benign tumor-like lesions located in the spine, as well as in cases of a double nidus. In comparison to radiofrequency ablation, percutaneous curettage enables obtaining valid histological specimens and does not bear the risk of thermal damage to neural tissue.