Introduction
Pigmented villonodular synovitis (PVNS) is an uncommon condition in which the lining of joints, tendons, or bursae grows excessively. It causes increased swelling and thickness in particular areas. It is not cancer and does not spread to other body parts. However, if left untreated, it can harm joints, cartilage, bone, ligaments, and tendons over time. This harm occurs because the swollen lining continues to develop and press into areas it is not supposed to. It can cause discomfort, stiffness, and a loss of normal joint motion. It is most commonly associated with the knee joint; however, it can also affect other joints. To treat it, the swollen lining must be removed surgically. If not removed, it can eventually damage the joint.
What Is the Epidemiology of Pigmented Villonodular Synovitis?
PVNS is extremely rare, affecting about one to two persons out of every million each year. It can occur at any age but is most frequent among adults between 20 to 50. It is significantly more prevalent in women than in men. The knee joint is most commonly afflicted, accounting for approximately 80 % of all cases. Following the knee, the hip, ankle, shoulder, and elbow joints may also be impacted. It rarely affects the back, hands, or feet.
What Is the Pathogenesis of Pigmented Villonodular Synovitis?
The precise cause of pigmented villonodular synovitis is unknown. Doctors have not discovered any definite inherited or environmental factors that trigger PVNS. However, research has identified several genetic alterations that appear to be associated. The primary change is the transfer of genetic material between chromosomes 1 and 2. This switch causes an overproduction of a protein known as CSF1. CSF1 regulates the formation and function of immune cells known as macrophages. When there is an excess of CSF1, macrophages develop abnormally. Up to 60 % of PVNS sufferers carry extra copies of the CSF1 gene. This results in the overproduction of CSF1. All of these genetic alterations cause excessive development of the joint lining. This enlarged joint lining causes the tumor-like lesions seen in PVNS.
Genetic alterations that elevate CSF1 stimulate abnormal macrophage proliferation, which causes the joint lining to overgrow, resulting in PVNS tumors. The causes that generate these precise genetic alterations remain unknown. More research is needed to completely understand the genetic alterations that appear to be the cause of this rare disease.
What Are the Clinical Presentations of Pigmented Villonodular Synovitis?
Patients with pigmented villonodular synovitis often develop symptoms gradually over time. They report swelling, discomfort, and stiffness in the affected joint. These symptoms frequently persist for months or even years before PVNS is diagnosed. The condition worsens progressively. As the tumor-like lesions grow, they can cause the joint to lock, snap, or catch. Even if there is no injury, patients may experience repeated blood-filled joint swelling. In severe situations, there may be thickening around the joint, tendon issues, and bone deterioration.
PVNS often only affects one joint. The knee is the most commonly affected joint. PVNS typically grows in the infrapatellar fat pad, which is located near the kneecap. This manifests as a mass at the front of the knee. PVNS in the hip frequently produces discomfort, stiffness, and soreness in the groin, inner thigh, or buttocks. The shoulder is less commonly affected, but when it is, there is widespread edema and loss of shoulder motion. The ankle and elbow can also be impacted, resulting in joint-specific edema, discomfort, and reduced mobility.
How to Diagnose Pigmented Villonodular Synovitis?
Pigmented villonodular synovitis is diagnosed with imaging exams, laboratory testing, and tissue samples because its symptoms are similar to those of other joint disorders. Regular X-rays can reveal late bone deterioration, but they usually appear normal early on. MRI (magnetic resonance imaging) scans are the greatest imaging test for detecting traditional symptoms such as thicker joint lining, fluid in the joint, and nodules. MRI can also reveal whether PVNS affects the entire joint or just one location.
An arthrocentesis, which involves inserting a needle to collect joint fluid, is another crucial diagnostic procedure. Finding blood-tinged fluid with inflammatory cells strongly supports PVNS. Under a microscope, the fluid reveals specific white blood cells, iron deposits, and even large cells. To confirm PVNS, a small portion of the joint lining must be removed and examined under a microscope.
The tissue sample shows specific features, including:
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Lumpy appearance.
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Excessive joint lining growth.
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Bleeding pigment.
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Foam cells.
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Giant cells.
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Inflammation.
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Scarring.
How to Treat Pigmented Villonodular Synovitis?
The primary treatment for pigmented villonodular synovitis (PVNS) is surgery to remove abnormal tissue. The goal is to remove all diseased synovium. This can be performed either by open surgery or arthroscopic surgery, depending on the location and severity of the condition. For localized PVNS, simply removing the nodule may be sufficient to cure the condition. However, for widespread PVNS, a larger resection of the thicker joint lining is required. Because PVNS can recur after surgery, performing the most comprehensive synovectomy possible upfront yields the best results.
Radiation therapy can be performed both before and after surgery, particularly for diffuse PVNS. It helps to reduce recurrence. For advanced PVNS that have damaged the joint, a complete joint replacement may be required. End-stage PVNS is most commonly treated with knee and hip replacements. PVNS, on the other hand, is more likely to reoccur following joint replacement than when diseased synovium is removed from native joints.
What Is the Prognosis of Pigmented Villonodular Synovitis?
The prognosis of PVNS is greatly impacted by disease severity. Localized PVNS has a slower overall progression than diffuse disease and lower recurrence rates after surgical excision. In contrast, diffuse PVNS has a higher recurrence incidence of 14 to 55 percent, even following a thorough synovectomy. The causes of recurrence are complex, including a high disease load, inadequate resection, and microscopic satellite lesions. Overall, the ten-year survival rate for PVNS is around 90 to 95 percent. PVNS rarely leads to death since it does not metastasize. However, locally aggressive illness can impair joint integrity and articular surfaces, resulting in early joint degeneration and loss of function. Regular clinical and radiographic surveillance is required for the early diagnosis of disease recurrence. This rare synovial condition requires a coordinated, interdisciplinary approach to be managed optimally.
Conclusion
In conclusion, pigmented villonodular synovitis is a rare and possibly destructive illness of the joint synovium. Due to its gradual onset and lack of distinct symptoms, diagnosis is frequently delayed. A combination of imaging, joint fluid study, and synovial biopsy can confirm the diagnosis. Treatment emphasizes thorough surgical excision, but recurrence rates are still significant, particularly for diffuse illness. Emerging radiation therapy approaches with personalized drugs provide hope for improved control of recurrent PVNS.
