Pigmented Villonodular Synovitis
PVNS is a very rare condition that may affect the foot or ankle. It is a painful thickening of the synovial tissue that lines a joint capsule or tendon sheath. PVNS tends to act like a slow-growing local tumor. However, it does not metastasize like a true cancer. Treatment requires surgical removal of all of the tissue. Recurrence of the PVNS is not uncommon.
Patients with PVNS have swelling around a joint or a tendon. Synovitis is inflammation and thickening of the smooth thin lining (synovium) of the tendon sheath or joint capsule. Synovitis is common, but PVNS is very rare. In fact it is usually only definitively diagnosed after surgical resection and analysis of the tissues by the pathologist. Patients with painful synovitis characterized by a thickened swollen painful tissue surrounding a tendon or joint may in rare instances turn out to have PVNS. PVNS Keeps on steadily growing like a localized tumor. However it does not metastasize.
Patients with PVNS will have localized painful swelling of the joint capsule or the tissue surrounding a tendon. Affected tissue is usually confined to one area unlike some other causes of synovitis such as rheumatoid arthritis.
Plain x-rays of the involved joint will usually be negative although there may be some subtle signs of a soft tissue shadow. If the PVNS has been present for a long time there may be some destruction of the associated joint.
MRI investigation can be helpful. It will demonstrate mark thickening of the associated synovium. It can help identify the extent of the synovitis.
Initially, the PVNS is likely to be treated like a typical synovitis. This would include activity modification, bracing, and possibly a corticosteroid injection. This approach will not be successful in the long run in patients with true PVNS as the tissue will keep growing.
Ultimately the inflamed synovium associated with PVNS needs to be removed surgically. Like a localized tumor, all of the tissue needs to be removed or it will tend to grow back and recur. This can be a challenge depending on the extent of the PVNS.
For difficult to eradicate or recurrent PVNS, it is sometimes necessary to consider other options in addition to surgery such as radiation treatment.
Edited May 23, 2017