Postradiation Extraskeletal Osteosarcoma Masquerading as an Axillary Artery Pseudoaneurysm.

BACKGROUND

A 68-year-old woman with a thoracoabdominal aortic aneurysm recently status after first-stage elephant trunk procedure with right brachiocephalic artery endarterectomy and reimplantation of the innominate and left carotid using a 14 × 10-mm branch graft presented to clinic with increasing pain in her right arm and shoulder for 2 weeks. She also had a remote history of radiation to the right axilla for breast cancer. On physical examination, she had a tender mass under her clavicle, numbness in shoulder and right hand weakness. Computed tomography scan revealed a 5.3 × 4.3-cm coarsely rim calcified lesion in the right axillary region reported as a pseudoaneurysm.

METHODS

She was taken to the operating room for exploration. After obtaining proximal and distal control, the mass revealed to be a solid tumor. The mass was removed, taking care to avoid the axillary artery and medial and lateral cords of the brachial plexus.

RESULTS

Pathology revealed an extraskeletal osteosarcoma.

CONCLUSIONS

Extraskeletal osteosarcoma is an extremely rare primary bone cancer, making up <1% of all osteosarcomas. Less than 350 cases are described in the literature. Of the cases described in the literature, less than 5% involve the upper extremity and/or thorax. They are aggressive tumors located in the soft tissue and not an extension of bone. Treatment involves multimodality therapy with surgical resection and adjuvant chemoradiation.