Extraskeletal Myxoid Chondrosarcoma of Thigh: A Case of Uncertain Origin

Abstract

Background: Extraskeletal myxoid chondrosarcoma (EMC) is a rare soft-tissue malignancy that accounts for less than 3% of all soft-tissue sarcomas. It arises in patients older than 35 years, with peak incidence during the 5th and 6th decades. It is distinguished from other sarcomas by its unique histology and a characteristic chromosomal translocation, typically t(9;22)(q22;q12.2), fusing EWSR1 to NR4A3. Case details:  A 60-year-old male presented with a slow-growing mass over the right side of his thigh for approximately one year. The patient complained of pain associated with the mass. FNAC showed a moderately cellular smear displaying chondromyxoid stroma. Suspicion of extraskeletal myxoid chondrosarcoma was made, and the mass was excised and sent to our department for histopathological examination. Grossly, the tumor was 16x14x10 cm, soft to firm, gray-tan colored, lobulated, and nodular. On the cut section, it had a gelatinous surface with cystic and solid areas. Microscopically, the tumor showed a multinodular pattern, with cells arranged in short cords and strands separated by myxoid material. Individual cells had round to oval nuclei with deeply eosinophilic cytoplasm. Few cells showed cytoplasmic vacuolization. Immunohistochemistry was done for further analysis using S100, Vimentin, and Synaptophysin. Conclusion: Extraskeletal myxoid chondrosarcoma is a tumor of uncertain differentiation. It has intermediate-grade malignant potential and can show metastasis or recurrence. Surgical excision is the treatment modality of choice.