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  • PVNS is a locally aggressive neoplastic synovial disease (not a true neoplasm) characterized by joint effusions, expansion of the synovium, and bony erosions
  • PVNS most commonly involves the knee, and typically presents with joint pain and swelling. Diagnosis is typically confirmed with MRI.
  • Treatment usually consists of surgical synovectomy. 
  • Epidemiology
    • incidence 
      • 9.2 per million per year in the United States
    • demographics
      • most commonly in adults age 30-40 but can occur at any age 
      • equal incidence in men and women
    • location
      • may occur locally (within a joint) or diffusely
      • localized (intra-articular or classic form) 
        • anterior knee is the most common site of involvement (80%) 
          • most commonly affects the patellofemoral compartment at the infrapatellar fat pad
        • knee > hip > ankle  > shoulder > elbow
      • diffuse (extra-articular extension)
        • behaves differently from localized
  • Pathophysiology
    • pathobiology
      • caused by an overexpression of CSF1 gene  
        • overexpression leads to clusters of aberrant cells creating focal areas of soft tissue hyperplasia in the synovial cells lining joints
      • a locally aggressive neoplastic synovial disease (not a true neoplasm) 
  • Genetics
    • mutations
      • locations of chromosome 1p13 in majority of cases
      • 5q33 chromosomal rearrangement 
  • Associated conditions
    • Giant Cell Tumor of Tendon Sheath  
      • also known as pigmented villonodular tumor of the tendon sheath (PVNTS)
  • Prognosis
    • PVNS is associated with a high rate of recurrence and accelerated degenerative changes of the knee ultimately requiring arthroplasty
      • TKA in patients with PVNS is associated with complication rates
Localized PVNS
Diffuse PVNS
Knee > hip > ankle
Knee (75%)
Gender Male = Female Female =/> Male
Painless, swollen joint, longstanding
Painful, swollen, tender, limited mobility
Osseous erosion from localized pressure
Degenerative changes on both sides of the joint
Well circumscribed soft tissue mass
Ill-defined (poorly circumscribed) soft tissue mass
8% after synovectomy
 30% after synovectomy
  • History
    • 50% of patients will have a prior history of trauma to the area
  • Symptoms
    • common symptoms
      • insidious onsent of pain in affected joint
      • stiffness in the affected joint
      • swelling in the affected joint
    • recurrent atraumatic hemarthrosis
      • is hallmark of disorder
  • Physical exam
    • inspection
      • joint effusion
      • erythema
    • palpation
      • tenderness along joint line
    • motion
      • limited motion of affected joint
  • Radiographs
    • recommended views
      • AP and lateral of affected joint
    • findings
      • soft tissue swelling
      • may show cystic erosion with sclerotic margins on both sides of the joint 
  • CT
    • indications
      • to evaluate for extent of cystic bone loss
    • findings
      • may show cystic erosions on both sides of the joint similar to radiographs  
  • MRI 
    • indications
      • most sensitive imaging study
      • provides excellent delineation of both intra-articular and extra-articular disease 
    • findings
      • reveals joint effusion, hemosiderin deposits, expansion of the synovium, and bony erosion 
      • low signal intensity on T1   
        • due to hemosiderin deposits
        • presence of fat signal (T1) within the lesion  
      • low signal intensity on T2  
      • "blooming artifact
        • signal loss on gradient-echo sequences 
        • because of iron in hemosiderin
      • extra-articular extension 
        • commonly see posterior extension outside of the knee joint of an intra-articular process
  • Labs
    • CRP and ESR
      • often normal despite signs of soft tissue swelling
  • Arthrocentesis
    • indication
      • recurrent hemarthrosis
    • findings
      • grossly bloody effusion 
  • Diagnostic arthroscopy
    • indications
      • gold standard for diagnosis 
      • synovial biopsy should be performed
    • findings
      • brownish or reddish inflamed synovium is typical of PVNS  
      • frond-like pattern of papillary projections
  • Histology
    • gross histology
      • shows a proliferative mass extending from the synovium  
    • low power
      • mononuclear stromal cells infiltrating the synovium 
      • highly vascular villi lined with plump hyperplastic synovial cells 
    • high power
      • hemosiderin stained multinucleated giant cells   
      • pigmented foam cells (lipid-laden histiocytes)
      • mitotic figures common
  • Synovial chondromatosis  
  • Hemophilia/hemarthrosis  
  • Rheumatoid arthritis 
  • Septic joints 
  • Other neoplasia
  • Nonoperative
    • observation
      • indications
        • asymptomatic disease only
    • CSF-1 receptor antagonist (pexidartinib) 
      • indications
        • approved in 2019 for use in patients with extensive disease who are not likely to benefit from surgical intervention
  • Operative
    • partial synovectomy 
      • indications
        • local form of PVNS   
      • technique
        • if lesion is accessible from anterior knee, this is can be done arthroscopically
        • posterior or extra-articular lesions should be performed open
    • total synovectomy +/- external beam radiation  
      • indications
        • in grossly symptomatic and painful disease
      • technique
        • total synovectomy is classified as marginal excision 
        • techniques range from arthroscopic to fully open total synovectomy depending on extent and location of disease
      • outcomes
        • improved functional and range of motion outcomes with arthroscopic technique
        • frequent recurrence is common
          • mostly due to incomplete synovectomy
      • external beam irradiation
        • technique
          • 30-35Gy in 15 fractions, or 50Gy in 25 fractions
        • outcomes
          • when combined with total synovectomy, reduces rate of recurrence to 10-20%
    • total synovectomy and total joint arthroplasty
      • indications
        •  advanced disease with severe degenerative joint changes i knee, hip, and shoulder
    • total synovectomy and arthrodesis
      • indications
        • severe disease of the ankle
  • CSF-1 receptor antagonist (pexidartinib)
    • technique
      • oral medication taken once daily for 24 weeks showed significant improvement of PVNS disease burden in ~40% of patients. 
    • complications
      • cholestatic hepatotoxicity was a noted side-effect of the drug
  • Arthroscopic synovectomy of knee for PVNS
    • approach 
      • routine arthroscopic portals for knee, ankle, and shoulder
    • technique
      • perform as thorough resection of synovium as possible through portals
      • can be challenging to access the posterior portions of the joint or extra-articular disease
  • Open posterior synovectomy of knee for PVNS
    • approach
      • posterior approach to the knee via transverse or S-shape incision across popliteal fossa 
      • approach between medial and lateral heads of gastrocnemius
      • retract neurovascular bundle to access posterior joint capsule
    • technique
      • disease is often seen posterior and extra-articular to the knee
      • complete posterior synovectomy and resection of extra-articular disease
    • complications
      • posterior approach to the knee places popliteal neurovascular bundle at risk
  • Recurrence 
    • incidence
      • recurrence is the most frequent complication for both intra-articular and extra-articular disease 
        • 30%-50% recurrence rate despite complete synovectomy
          • same rates for complete open vs open+arthroscopic
        • rates can be reduced with addition of external beam radiation
  • Joint destruction
    • moderate to severe joint deformity
    • treatment
      • may lead to the need for arthrodesis or amputation
  • Skin necrosis, radiation induced sarcoma
    • risk factors
      • radiation therapy

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