Extraskeletal myxoid chondrosarcoma: A case series and review of the literature

Background: Extraskeletal myxoid chondrosarcoma (EMC) is a rare malignant soft tissue sarcoma (STS) that accounts for less than 3% of all soft tissue tumors. The conventional treatment for primary EMC is wide local excision with or without radiation therapy. Materials and Methods: This study was a retrospective review of all EMC cases treated within a single institution between 1992 and 2019. EMC was diagnosed using a combination of histologic morphology and immunostaining, with confirmatory fluorescent in situ hybridization. Overall survival (OS) and disease-specific survival (DSS) were defined using Kaplan-Meier analysis. Results: Fifteen patients were evaluated, including II males and four females. The average age at presentation was 51.7 +/- 20.4 years and the mean follow-up time was 61.5 months (range, 5-286 months). The average resected tumor size at largest dimension was 7.14 cm (range, 2.4-18.7). Twelve of fifteen (80%) patients underwent wide local excision, and nine of the twelve (75%) underwent local radiation therapy. The 1 -, 5-, and 10-year OS was 80% (95% CI, 59.8-100), 72% (95% CI, 48.5-95.5), and 72% (95% CI, 48.5-95.5), respectively. The 1-, 5-, and 10-year DSS was 92.3% (95% CI, 77.8-100), 83.1% (95% CI, 61.5-100), and 83.1% (95% CI, 61.5-100), respectively. At last follow-up, II patients were alive and ten (90.9%) were disease free. Conclusions: Extraskeletal myxoid chondrosarcoma is a very rare STS most often seen in males and in the extremities. Our cohort was too small to provide meaningful statistical analysis; however, we observed lower rates of local recurrence in patients treated with radiation.