Recurrent joint pain and swelling usually result from common conditions such as osteoarthritis or inflammatory arthritis, such as gout. One rare cause of recurrent joint swelling is pigmented villonodular synovitis, or PVNS. So what is PVNS, and how do we diagnose and treat it?
What is PVNS?
PVNS occurs when the tissue lining the joint — the synovial lining — overgrows and thickens, forming villous (finger-like) projections. This abnormal tissue often contains haemosiderin, a breakdown product of blood, which causes blood-stained joint swelling. Over time, PVNS can damage the surrounding cartilage and bone. Although it’s often described as a tumour, it isn’t usually cancerous.
You may also see PVNS referred to as a tenosynovial giant cell tumour (TSGCT) — the modern term for this group of conditions. The diffuse form (affecting the whole joint lining) is sometimes called diffuse-type TSGCT, and the localised form, localised-type.
PVNS is rare, affecting roughly two people per million each year. It most often involves the knee, but can also affect the hip, shoulder, elbow, and ankle. In one study of 90 people with PVNS, over 90% of cases were in these joints. It can be localised to one area or diffuse, involving the entire synovial lining.
Symptoms and signs of PVNS
PVNS usually affects a single joint, though occasionally more than one. Common features include:
- Joint swelling — persistent, and often painless in the early stages, worsening over time. PVNS can also present as a painless lump on the wrist or lower leg.
- Pain — an aching or throbbing joint pain that worsens with activity.
- Stiffness — a reduced range of movement.
- Locking or clicking — mechanical symptoms from the swelling or tissue overgrowth.
- Warmth and tenderness over the joint.
- Recurrent hemarthrosis — blood within the joint, often after minor trauma.
How do we diagnose PVNS?
Your doctor examines the joint for swelling, tenderness, and restricted movement, then uses imaging to confirm the diagnosis.
MRI is the gold standard. It shows the characteristic features — synovial thickening, haemosiderin deposition, and joint effusion. A specific MRI sequence (gradient echo) produces a “blooming” effect that’s highly characteristic of PVNS. These sequences aren’t part of a standard joint scan, so if your doctor suspects PVNS, you may need additional sequences to confirm it.
A biopsy of the synovial tissue can give more information, which can be examined under the microscope for the cell changes typical of PVNS.
Treatment options for PVNS
Once we’ve made the diagnosis, anti-inflammatories can reduce pain and swelling in the short term. But because PVNS can cause progressive joint damage, more definitive treatment is usually needed.
Surgery is the most definitive treatment. A localised tumour can be surgically removed; a diffuse one may require arthroscopic or open synovectomy (removal of the affected joint lining). In some cases, PVNS returns after surgery.
Radiation therapy is sometimes used when the tumour has recurred or can’t be fully removed, to shrink it and reduce the risk of recurrence.
Targeted drug therapy is a newer option for diffuse or recurrent disease that isn’t suitable for surgery. Medications that block a signalling pathway driving the tumour (CSF1 inhibitors, such as pexidartinib) can reduce its size — these are specialist treatments used under the care of a sarcoma or oncology team.
Frequently asked questions about PVNS.
How rare is PVNS?
Very rare — roughly two people per million develop it each year. It most often affects the knee.
What causes PVNS?
The cause isn’t known. Around half of cases are preceded by trauma, which suggests bleeding into the joint may trigger the overgrowth of the synovium.
Is PVNS a cancer?
PVNS isn’t usually cancerous, though it’s described as a tumour because it’s an overgrowth of tissue that can behave aggressively locally, damaging cartilage and bone and recurring after treatment. Spread to other parts of the body is very rare.
Can PVNS occur outside a joint?
Yes — this is called giant cell tumour of the tendon sheath (GCTTS), the localised, extra-articular form. It’s more common in women aged 30–50 and usually affects the wrist and hand. As with PVNS, MRI with gradient-echo sequences is the gold standard for diagnosis, though ultrasound can also help.
Does PVNS come back after surgery?
It can, particularly the diffuse form. This is why some people need radiation or targeted drug therapy in addition to surgery, and why follow-up matters after treatment.
Final word from Sport Doctor London about PVNS
Pigmented villonodular synovitis is challenging because of its rarity, variable presentation, and potential to destroy a joint. If you have persistent joint swelling, pain, or dysfunction, see a sports medicine doctor for assessment. Advances in imaging, surgery, and targeted therapy continue to improve outcomes in PVNS.
If you have unexplained, recurrent joint swelling, Dr Masci can assess you in London and arrange the right imaging. Contact the team here or call +44 (0) 203 488 0350.
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