Synovial Sarcoma
Synovioma

• Middle-aged and older adults
• Most frequent presentation: painful swelling of the knee
• Predisposition for lower extremity
• It is a malignancy
• Can occur at any age
• Usually third and fourth decades
• Usually are extra-articular
• X-ray
• Soft tissue mass near articular surface
• Frequently, spherical and lobulated in shape
• 20-30% calcify
• About 1/3 have adjacent erosion of bone
• Look for erosions on both sides of a joint
• Osteoporosis is common secondary to disuse
• DDX from pigmented villonodular synovitis where there is rarely osteoporosis
• Can metastasize to lungs
• Mets to lungs almost never calcify
• Mets to bone itself very rare
• Prognosis is poor
• Benign variety occurs in the joint capsule around knee
• DDX:
• Tumoral calcinosis

Synovial Sarcoma. Frontal radiograph of the foot demonstrates a heavily calcified
 lesion which is arising from the dorsum of the foot between the 2nd and 3rd metatarsals (white arrows)..
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