Synovioma
Synovial Sarcoma

• 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

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.

• 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