Locally recurrent extraskeletal myxoid chondrosarcoma of the shoulder: a case of complete neoadjuvant radiotherapy response.

Background: Extraskeletal myxoid chondrosarcoma (EMC) is a rare soft tissue tumor that typically affects the lower limbs of men between the ages of 50 and 60. EMC of the shoulder is rare with a high risk of local recurrence and distant metastasis. A planned surgical excision in sarcoma referral centers (SRCs) is mandatory to obtain the best outcome. The role of chemotherapy (CHT) and Radiotherapy (RT) on soft tissue chondrosarcoma is still controversial.

Case presentation: A 47-year-old man presented to our referral center with a history of EMC in the right shoulder excised with microscopic positive surgical margins in a non-referral center. Staging imaging exams did not reveal distant metastasis or residual disease, but during follow-up a local recurrence was detected. After a multidisciplinary discussion, preoperative radiotherapy was administered with a total dose of 50 Gy, and then the patient underwent wide surgical excision. Histological examination was negative for viable tumor cells. No relapse occurred in a 24-months post-operative follow up.

Conclusions: The case here described suggests the importance of patient's management in SRCs. A planned combined treatments with both surgery and RT seems to be the best choice to improve local control. RT seems to be promising within this specific histotype. Further studies are needed to confirm if the observed efficacy of combined treatments reflects in a consistent survival benefit for EMC patients.