Extraskeletal osteosarcoma misdiagnosed as metastatic breast cancer: A case report

Introduction

Extraskeletal osteosarcomas are rare tumors with poor overall survival and a high propensity for recurrence. It frequently arises in the lower extremities and has been reported to metastasize commonly in the lungs. Controversy exists as to whether it should be treated as a soft tissue sarcoma or an osteosarcoma. Various adjuvant treatment approaches have also been studied with conflicting results.

Case report

We present a 73-year-old female with a painless, gradually enlarging right upper arm mass for 2 months. She previously underwent a left mastectomy 5 years ago for a stage II breast cancer. Preoperative imaging showed a resectable, heterogenous right upper arm mass. She subsequently underwent radical excision with frozen section revealing spindle cell neoplasm. Final histopathology was consistent with extraskeletal osteosarcoma. The patient remains disease-free as of most recent follow-up.

Discussion

There are several proposed mechanisms for extraskeletal osteosarcomas. Based on the history and location of the tumor, we initially thought that this was metastatic breast cancer. Preoperative imaging determines resectability and surgical approach. Radical surgery is frequently performed which largely depends on the site of the tumor. Complete primary resection with adequate margins remains to be the treatment of choice to prevent recurrence or metastasis. The role of adjuvant radiotherapy or chemotherapy is still to be established.

Conclusion

This case highlights the various treatment options and the need for further research on its clinical behavior and potential targeted therapies.