1163

Abstract

Introduction: Aneurysmal bone cyst (ABC) is a rare benign bone tumor. It most commonly occurs in the long bones or the spine, but can occur in any bone. En bloc resection carries the lowest risk of recurrence, but there is controversy over the best treatment approach with large lesions adjacent to vital structures. Case: A 17-year-old previously healthy girl presented with cough and dyspnea. Chest radiograph showed a left apical round opacity. She was treated for presumed pneumonia, but was lost to follow-up. She presented three months later with persistent symptoms. Chest radiograph showed an enlarging opacity. CT scan demonstrated a large multi-cystic lesion arising from the left third rib, expanding into the left chest with deviation of the trachea and great vessels. Biopsy was consistent with ABC. Due to concern of bleeding with surgical resection, pre-operative selective arterial embolization (SAE) was attempted. On angiography, the mass was found to have blood supply from a lower branch of the thyrocervical trunk, and it was embolized with Embozene microspheres and coils. Post-procedure, the patient did not awaken from anesthesia. Brain MRI demonstrated diffuse acute infarction prominent in the posterior circulation. She remained unresponsive and required mechanical ventilation. She had minimal neurologic recovery, and was weaned from mechanical ventilation after three weeks. Rehabilitation is ongoing. The mass is stable in size after one month, and no additional intervention has yet been attempted. Discussion: To our knowledge, this is the first reported case of ABC of the rib treated with SAE. SAE has been successfully reported in other locations as a pre-operative adjunct to reduce risk of bleeding or even as a definitive therapy. Some have proposed cautious use in spinal ABC due to concern of shared circulation with the spinal cord. In this case, embolic stroke may have been caused by unrecognized shared circulation between the mass and the vertebral artery. Primary surgical resection may be more strongly considered in rib ABC or other chest wall masses due to the potential risk of SAE when shared circulation with vital structures is possible.