Pigmented Villonodular Synovitis (PVNS): Causes, Treatment, and Recurrence Rates
Learn about Pigmented Villonodular Synovitis, its diagnosis, treatment, and epidemiology.
Pigmented Villonodular Synovitis (PVNS) is a locally aggressive neoplastic synovial disease characterized by joint effusions, expansion of the synovium, and bony erosions. PVNS usually presents in patients between 30 and 40 years old with recurrent atraumatic knee hemarthrosis.
EPIDEMIOLOGY
| Incidence | rare 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 |
| Anatomic 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%) knee > hip > ankle > shoulder > elbow diffuse (extra-articular extension) behaves differently from localized |
ETIOLOGY
PVNS is caused by an overexpression of CSF1 gene which leads to clusters of aberrant cells creating focal areas of soft tissue hyperplasia in the synovial cells lining joints. PVNS is a locally aggressive neoplastic synovial disease.
CLASSIFICATION
| Characteristic | Localized PVNS | Diffuse PVNS |
|---|---|---|
| Location | Knee > hip > ankle | Knee (75%) |
| Age | 30-50y | <40y |
| Gender | Male = Female | Female >= Male |
| Presentation | Painless, swollen joint, longstanding | Painful, swollen, tender, limited mobility |
| Radiograph | Osseous erosion from localized pressure | Degenerative changes on both sides of the joint |
| MRI | Well circumscribed soft tissue mass | Ill-defined (poorly circumscribed) soft tissue mass |
| Recurrence | 8% after synovectomy | 30% after synovectomy |
PRESENTATION
The hallmark of PVNS is recurrent atraumatic hemarthrosis. Patients may also experience insidious onset of pain, stiffness, and swelling in the affected joint. Clinical examination typically reveals joint effusion and tenderness along the joint line.
IMAGING
Radiographs may show cystic erosions with sclerotic margins on both sides of the joint. MRI is the most sensitive imaging study and reveals joint effusion, hemosiderin deposits, expansion of the synovium, and bony erosion. Arthrocentesis typically reveals a brown fluid. Diagnostic arthroscopy is the gold standard for diagnosis and synovial biopsy should be performed.
TREATMENT
Treatment generally consists of partial or total surgical synovectomy depending on presence of localized or diffuse PVNS. Nonoperational options include observation and usage of oral medication Pexidartinib. In grossly symptomatic and painful disease, total synovectomy +/- external beam radiation is recommended.
TECHNIQUES
- CSF-1 receptor antagonist (pexidartinib): oral medication taken once daily for 24 weeks showed significant improvement of PVNS disease burden in ~40% of patients.
- Arthroscopic synovectomy of knee for PVNS: performed as thorough resection of synovium as possible through portals.
- Open posterior synovectomy of knee for PVNS: complete posterior synovectomy and resection of extra-articular disease. Posterior approach to the knee places popliteal neurovascular bundle at risk.
COMPLICATIONS
- Recurrence: 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 may lead to the need for arthrodesis or amputation.
- Skin necrosis, radiation induced sarcoma: risk factors of radiation therapy.
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.
Summary Pigmented Villonodular Synovitis
Pigmented Villonodular Synovitis (PVNS) is a neoplastic synovial disease characterized by joint effusions, synovial expansion, and bony erosions. It is a rare condition with an incidence of 9.2 cases per million per year in the United States. PVNS usually affects adults between the ages of 30 and 40, although it can occur at any age, and it is equally common in men and women. PVNS can occur locally within a joint (localized PVNS) or extend beyond the joint (diffuse PVNS). The most common site of involvement is the anterior knee, followed by the hip, ankle, shoulder, and elbow. The presentation of PVNS includes recurrent atraumatic knee hemarthrosis, as well as pain, stiffness, and swelling in the affected joint. Clinical examination reveals joint effusion and tenderness along the joint line. The etiology of PVNS involves an overexpression of the CSF1 gene, which leads to the formation of clusters of aberrant cells in the synovial tissue. This causes soft tissue hyperplasia and the characteristic features of PVNS. PVNS can be classified as either localized or diffuse based on its location, age of onset, gender distribution, presentation, radiographic findings, MRI appearance, and recurrence after synovectomy. Localized PVNS is typically painless with longstanding joint swelling, while diffuse PVNS is painful, swollen, tender, and limited in mobility. Radiographs may show cystic erosions with sclerotic margins on both sides of the joint, while MRI is the most sensitive imaging study for PVNS, revealing joint effusion, hemosiderin deposits, synovial expansion, and bony erosion. Arthrocentesis typically reveals brown fluid, and diagnostic arthroscopy with synovial biopsy is the gold standard for diagnosis. Treatment for PVNS involves surgical synovectomy, either partial or total, depending on the extent of the disease. Nonoperative options include observation or the use of the oral medication Pexidartinib. In symptomatic and painful cases, total synovectomy with or without external beam radiation is recommended. Recurrence rates after synovectomy range from 8% in localized PVNS to 30% in diffuse PVNS. Complications of PVNS include recurrence, joint destruction leading to the need for arthrodesis or amputation, and rare complications such as skin necrosis and radiation-induced sarcoma. Overall, PVNS has a high rate of recurrence and can lead to accelerated degenerative changes in the affected joint, often requiring arthroplasty.Learn about the causes, treatment options, and recurrence rates of Pigmented Villonodular Synovitis (PVNS), a rare neoplastic synovial disease that affects the joints. Find out about the symptoms, diagnosis, and surgical interventions for PVNS.