Neoadjuvant Radiotherapy in the Treatment of Extraskeletal Myxoid Chondrosarcoma: A Case Report

Extraskeletal myxoid chondrosarcoma (EMC) is a rare soft tissue sarcoma, constituting <3% of soft tissue tumors. Initially considered a low-grade sarcoma, but with evidence of local recurrences and distant metastases, it is now considered an intermediate-to-high-grade sarcoma. It is characterized by a chromosomal translocation t(9,22), which results in EWSR1 fusing to NR4A3. Wide local excision with or without radiotherapy remains the mainstay of treatment for localized disease. Here, we present a case report of nonmetastatic NR4A3-positive EMC, treated by neoadjuvant radiation therapy followed by wide local excision. We report the case of a 70-year-old gentleman who presented to our Oncology Clinic with complaints of progressive swelling over his left thigh for a duration of 4 months. Contrast-enhanced magnetic resonance imaging showed a large, well-defined mass involving the vastus lateralis and intermedius muscles and abutting the femoral vessels. Ultrasound-guided TruCut biopsy revealed EMC with NR4A3 translocation on molecular study. He was confirmed nonmetastatic on a whole-body positron emission tomography-computed tomography scan. He underwent neoadjuvant radiation therapy followed by wide local excision of the tumor. At 2-year follow-up, he is asymptomatic, without any clinical or radiological evidence of the disease. EMC is an ultra-rare soft tissue sarcoma with a characteristic chromosomal translocation, long indolent clinical course, and high rates of local recurrence and distant metastases. Multimodal treatment with radiation therapy and surgery, long-term follow-up has been found to reduce the rates of local recurrence and distant metastases.