Pigmented Villonodular Synovitis

Definition

  • A locally aggressive synovial tumour which affects both large joints & tendon sheaths
  • Same entity as giant cell tumour of tendon sheath

Terminology

  • Other names for this disorder have included
    • synovial xanthoma
    • synovial fibroendothelioma
    • synovial endothelioma
    • benign fibrous histiocytoma
    • xanthomatous giant cell tumour
    • myeloplaxoma
    • chronic haemorrhagic villous synovitis

Epidemiology

  • 1.8 per million
  • No sex or racial predilection
  • Most common in the 20s & 30s

Aetiology

  • Essentially unknown
  • Theories
    • Hirohata
      • localised disturbance in the metabolism of lipids
    • Trauma.
      • However, low incidence in patients with haemorrhagic disorders, & has not been consistently reproduced in experimental animals
    • Inflammation
      • Widest held theory since 1941 (Jaffe)
      • Trigger for inflammation has not been identified

Pathology

Gross

  • Tan colour
  • In the knee usually consists of multiple nodules, often with dramatic associated hyperplastic villous changes in the synovium, giving a straggly beard appearance
  • Extensive haemosiderin deposition

Microscopic

Histology of pigmented villonodular synovitis
Histology of pigmented villonodular synovitis. Image by Nephron, Wikimedia Commons, CC BY-SA 3.0.
  • Proliferating, collagen producing polyhedral cells
  • Often scattered multinucleated giant cells
  • Foam cells
  • Haemosiderin

Clinical Presentation

  • Much more frequently found as a solitary nodule & more rarely as a diffuse multinodular condition
  • Most common sites are the knees & fingers
  • Can also occur in the wrist, hip, ankle & toes
  • Usually painless or only mildly painful. Onset is insidious
  • Approximately 50% can recall an episode of trauma

Signs

  • Local warmth
  • Swelling
  • Stiffness
  • Palpable mass
  • Point tenderness in 50%

Investigations

Aspiration

  • produces a deep xanthochromic to brownish stained bloody fluid

X-ray

CT of pigmented villonodular synovitis of the hip
CT of pigmented villonodular synovitis of the hip. Image by Ruiz Santiago, Fernando, Santiago Chinchilla, Alicia, Ansari, Afshin, Guzmán Álvarez, Luis, Castellano García, Maria del Mar, Martínez Martínez, Alberto, Tercedor Sánchez, Juan, Wikimedia Commons, CC BY 4.0.
  • Fingers
    • usually only soft tissue swelling or there may be cortical erosion
  • Knee
    • major finding is soft tissue swelling which may be massive
  • Erosion may cause a lytic intramedullary lesion. Erosion is rare in the knee because a substantial bulk of tumour can be accommodated, but is more common in the hip
  • Lucencies on either side of a joint are very characteristic of PVNS
  • Findings of extension outside the joint, calcification or cortical destruction suggest the diagnosis of synovial sarcoma

MRI

  • low to intermediate signal intensity on T1 & T2 weighted images

Treatment

  • Excision
    • Options
      • arthroscopic
      • open using anterior & posterior approaches
        • In the posterior approach, a lazy S incision is made, the gastrocnemius heads are released & the capsule opened using two T shaped incisions, one medial & one lateral
        • menisci are detached both anteriorly & posteriorly & are later repaired
  • Radiation synovectomy
    • Radiocolloid yttrium-90 is injected into the knee
    • Doesn’t appear to affect the knee cartilage
  • External beam irradiation
    • may be used. One dosage that has been used is 35Gy
    • Tends to be used in recurrences
  • Arthrodesis
    • End stage destruction, particularly in the ankle, often requires arthrodesis

Prognosis

  • Metastatic disease may develop
  • MRI is effective in detecting recurrence postoperatively
  • Recurrence is common in the diffuse form of the disease
  • E.g. 33% in a series of 18 patients with PVNS of the knee
  • In the localised form recurrence is uncommon

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.