Pigmented Villonodular Synovitis (PVNS)

What is Pigmented Villonodular Synovitis (PVNS)?

Pigmented Villonodular Synovitis (PVNS) is a rare, non-cancerous overgrowth of the synovium (the lining of your joint). In PVNS the lining thickens, bleeds and forms a pigmented (“brown”) mass. Over time, this can damage cartilage and bone, causing pain, swelling and reduced movement in the affected joint (most often the knee). Early diagnosis and treatment help protect joint function.

Why does PVNS happen?

• Unknown trigger: The exact cause remains unclear.
• Cell signals: A faulty gene causes joint cells to over-produce a growth factor (CSF-1), leading to synovial overgrowth.
• Repeated bleeding: Fragile new vessels leak blood, depositing iron (hemosiderin) which gives PVNS its brown colour.

00Who gets PVNS?

• Age group: Most common in adults aged 20–50, rare in children.
• Gender: Affects men and women equally.
• Joint: Knee is involved in 75–80% of cases; hip, ankle, shoulder or elbow can also be affected.

Recognising the symptoms

• Joint swelling—often sudden and may be bloody
• Pain—may start mild and worsen over months
• Stiffness—difficulty fully bending or straightening
• Mechanical signs—catching, locking or a sense of your joint “giving way”
• Palpable lump—in localized PVNS, a slow-growing painless nodule may be felt

00How is PVNS diagnosed?

1. Clinical assessment: Doctor checks for effusion (fluid), tenderness and movement.
2. X-ray: May show joint swelling or early bone erosions.
3. MRI scan: The best test to see pigmented synovium, joint fluid and bony damage.
4. Joint aspiration: Fluid may appear dark brown or bloody.
5. Biopsy (arthroscopy): Gold standard—small tissue sample confirms pigmented cells and giant-cell clusters.

Treatment options

• Arthroscopic synovectomy (keyhole removal of diseased lining)—first choice for most cases
• Open synovectomy—for extensive disease, ensures complete removal
• Combined approach—keyhole plus small open incision for diffuse knee involvement
• Targeted drugs (e.g. pexidartinib)—for stubborn or widespread disease not suitable for surgery
• Radiation therapy—often used after surgery to reduce recurrence in diffuse PVNS
• Joint replacement—reserved for severe joint destruction
• Observation only—in rare, asymptomatic childhood cases

Living well with PVNS

• Early treatment protects cartilage and bone
• Regular follow-up with imaging to spot recurrence
• Physiotherapy to restore strength and range of motion
• Weight management and low-impact exercise (swimming, cycling) to ease joint load

00Clinical Pearls / Key Points

• PVNS is benign but locally aggressive—prompt removal prevents joint damage
• MRI is essential for planning surgery and assessing extent
• Diffuse PVNS has a higher recurrence (up to 50 %) than localized (≈ 8 %)
• Pexidartinib targets the CSF-1 receptor, shrinking tumours in around 40 % of cases
• Combined arthroscopic/open surgery plus radiotherapy gives best long-term control of diffuse disease

Patient FAQs

Is PVNS cancer?
No. PVNS is benign (non-malignant), but it can be aggressive locally and damage the joint if untreated.

Can PVNS spread to other joints?
PVNS normally affects only one joint. Spread to other joints is extremely rare.

What are the risks of surgery?
Key risks include infection, stiffness and recurrence of PVNS. Your surgeon will discuss ways to minimise these.

Will PVNS come back after treatment?
Diffuse PVNS recurs more often (20–50 %) than localized PVNS (≈ 8 %). Radiation or targeted drugs can reduce this risk.

How soon can I exercise after surgery?
Light movement usually begins within days. Your physiotherapist will guide a tailored rehabilitation plan.

Call-to-Action

For personalised advice, surgical consultation or rehabilitation plans, visit www.TheArmDoc.co.uk/PVNS or call 020 3384 5588 to book your appointment today.

Evidence & Guidelines

• National Institute for Health and Care Excellence (NICE): Management of soft-tissue tumours (2022)
• American Academy of Orthopaedic Surgeons (AAOS): Synovial Disorders Guideline (2023)
• Cochrane Review: Synovectomy vs observation in PVNS (2021)

Disclaimer
This page is for patient education only and does not replace professional medical advice. Always consult your clinician for individual assessment and treatment.