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synovial sarcomaA mesenchymal spindle cell tumour which comprises ±10% of all soft-tissue sarcomas. It is most common in young (age 20 to 40) males, and occurs most commonly around the large joints—knee, ankle, foot, 60% in the legs, 23% in upper extremity. However, it can go any place, as cases have been reported in the penis, lung, vulva, abdominal wall, etc.
50% 5-year survival; extensively calcified synovial sarcomas have a higher (84%) 5-year survival; 40% metastasise to lungs, bone-regional nodes.
Good prognostic factors
Children; < 5cm; <10 mitoses/10hpf; no necrosis; complete excision in first attempt.
Older age, larger size (especially, > 35 cm), necrosis, vascular invasion, high Ki-67 index, high-grade nuclei, poorly differentiated areas, known recurrence.
Synovial sarcoma, histologic types
• Distinct epithelial and spindle cell components.
DiffDx, Spindle cell type
Malignant peripheral-nerve sheath tumour, schwanoma, solitary fibrous tumour, fasciitis.
DiffDx, Glandular cell type
Ewing sarcoma and other small round cell tumours.
synoviosarcoma[+ Gr. sarx, flesh + oma, tumor]
A rare malignant tumor that arises from synovial cells, i.e., the cells of the membranes that enclose joints.