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Pigmented Villonodular Synovitis

  • PVNS is an uncommon lesion characterized by diffuse proliferation of the synovium to form yellow-brown villous projections.
  • The knee is the most commonly affected joint, followed by the hip and shoulders.
  • Lesions almost always are unilateral.
  • Synonyms: Giant cell tumor of the tendon sheaths and joints; Hemorrhagic villous synovitis
  • Usually found in young to middle-aged adults
  • No definite gender correlation; may have slight female predominance
Risk Factors
PVNS may have a slight association with recurrent hemarthrosis, but it has not been established definitively.
No known correlation exists.
  • The cause is unknown.
  • Studies in animals have produced similar lesions in response to recurrent hemarthroses, but lesions resolve when the inciting stimulus is removed.
  • In humans, slow progression of PVNS is the rule.
Associated Conditions
None are known.
Signs and Symptoms
  • Insidious onset
  • Slow progression
  • Recurrent nontraumatic effusions
  • Symptoms:
    • Pain
    • Swelling
    • Limitation of ROM
  • Joint possibly warm to the touch
  • Mild to moderate effusion
  • Tender mass occasionally palpated (especially in the suprapatellar pouch of the knee)
Physical Exam
  • Perform a complete examination of the knee, looking for the following:
    • Ligamentous and meniscal status
    • Possible effusion
    • Warmth at the joint
    • Pain
    • Swelling
    • Tender mass
  • Determine the ROM of the affected joint.
  • Assess for muscle atrophy.
  • With shoulder, ankle, and hip involvement, no physical findings or only subtle findings may be present, such as muscle atrophy or decreased ROM.
Joint aspiration reveals reddish brown fluid.
  • Radiography:
    • Early findings:
      • Frequently no abnormalities
      • Subtle erosions or periosteal reaction in nonweightbearing regions
    • Late findings:
      • Erosive lesions on both sides of the joint
      • Possible diffuse joint space narrowing seen in late cases
  • MRI:
    • Increasingly helpful in establishing the diagnosis and directing treatment
    • Areas of extremely low signal are seen in the synovial lining on both T1- and T2-weighted images (signal dropout).
    • Characteristically, joint effusion and irregularity of the synovial lining are seen.
Pathological Findings
  • Lesions may be large and diffuse or more discrete.
  • Grossly, PVNS is characterized by villous projections or matted nodules stained with hemosiderin.
  • Microscopically, elongated villi or nodules contain inflammatory infiltrates, foamy histiocytes, and hemosiderin deposits.
Differential Diagnosis
  • Inflammatory arthritis
  • Traumatic effusions
  • Infection
  • Synovial sarcoma
  • Hemosiderosis
  • Hemochromatosis
General Measures
  • PVNS is a benign lesion.
    • The potential for malignant degeneration has been reported but is extremely rare.
  • In diffuse lesions:
    • It is almost impossible to remove the entire lesion without injuring important ligaments and capsular structure.
    • Therefore, the recurrence rate is high.
  • In severe or recurrent cases, radiotherapy has been effective.
  • Make appropriate referrals to establish the diagnosis and consider treatment options.
  • Treat patients symptomatically with:
    • Immobilization
    • Splinting
    • NSAIDs
    • Analgesics
Special Therapy
  • External beam irradiation is commonly used for recurrent PVNS.
  • Radiation synovectomy with an intra-articular injection of radioactive isotope also has been used.
  • Analgesics
  • Arthroscopic synovectomy through multiple portals is the 1st line of treatment for diffuse PVNS.
    • An open posterior synovectomy may be necessary with extensive posterior extra-articular extension.
  • Some surgeons prefer both open anterior and posterior synovectomies for diffuse PVNS.
  • Localized, nodular PVNS responds well to simple excision (open or arthroscopic).
Patients are followed every 6-12 months with MRI scans and physical examination.
The prognosis is good.
  • Recurrence is common.
  • Articular damage and bone loss may occur in long-standing disease.
  • Joint replacement may be necessary.
Patient Monitoring
  • MRI is effective in detecting early local recurrences.
  • Patients with asymptomatic local recurrences are treated with observation.
215.3 Benign neoplasm, knee
Patient Teaching
Even with appropriate care, the recurrence rate is high, especially in diffuse PVNS.
After surgery, ROM exercises are important to prevent contractures.
Q: Is irradiation effective in controlling recurrent disease?
A: External beam irradiation, when combined with repeat surgery, can be very effective.
Q: How do patients know if they have PVNS in 1 of their joints?
A: Patients most commonly present with severe joint pain and palpable swelling in superficial joints.
Q: When do patients with PVNS need a joint replacement?
A: Joint replacement surgery is needed when the joint surfaces have been destroyed or the bone involvement is so severe that curettage and grafting is not feasible.

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