extraskeletal myxoid chondrosarcoma

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extraskeletal myxoid chondrosarcoma

A phenotypically and genotypically distinct mesenchymal malignancy with tumour-specific fusion genes, which affects older adults and represents 2.5% of soft tissue sarcomas. ESMCS differs from the primary skeletal chondrosarcoma given the myxoid changes, and is classified as a tumour of uncertain differentiation. It arises in the deep soft tissues of the leg in 75% of cases (thigh, popliteal fossa and buttock). 80% occur in the proximal extremities and limb girdles; 20% in the trunk.

Extraskeletal myxoid chondrosarcoma
• Cellular variant without myxoid matrix;
• Classical variant;
• Dedifferentiated type;
• Epithelioid type;
• Rhabdoid type;
• Small cell type.

Imaging
Cortical erosion and buttressing.

Epidemiology
Male:female ratio, 2:1.

DiffDx
Intramuscular myxoma, myxoid liposarcoma, fibromyxoid sarcoma, myxoid embryonal rhabdomyosarcoma.
 
Differentiation
Cartilaginous, neuroendocrine, neural.

Management
Surgical excision; adjuvant chemotherapy if nodal spread or metastasis.

Prognosis
Frequent local recurrence; late metastases; 5-year, 10-year, 15-year survival, 90%, 70%, 60% respectively; continued follow-up is necessary.