Pigmented Villonodular Synovitis, or PVNS, is a non-cancerous condition that affects the joints. It involves an overgrowth and thickening of the synovium, which is the specialized tissue lining the inside of joints and tendons. This proliferation forms a mass or tumor within the joint space. Although it does not spread to other parts of the body, PVNS is a progressive disease that can worsen over time.
Understanding PVNS
In PVNS, the synovium, the thin tissue lining joints, thickens and overgrows. In a healthy joint, the synovium produces a small amount of lubricating fluid for cartilage and smooth movement. With PVNS, the overgrown synovium produces excess fluid, which results in joint swelling and significant pain during movement.
This condition affects only one joint, with the knee involved in approximately 80% of patients. Other joints that can be affected include the hip, ankle, shoulder, and elbow.
It can occur in individuals of all ages, but is most frequently observed in young adults (20-50 years old). The condition presents in two forms: localized and diffuse PVNS. These forms describe the extent of synovial overgrowth.
Causes of PVNS
The precise cause of Pigmented Villonodular Synovitis remains unknown. Researchers have identified certain genetic changes associated with the condition, though a direct genetic cause is not yet clear and remains an area of ongoing study.
In some individuals, cells within the affected joint lining exhibit a defect. This defect leads to excess production of a protein known as colony-stimulating factor 1 receptor (CSF-1R). Research indicates this protein plays a role in PVNS development and progression.
Recognizing Symptoms and Diagnosis
PVNS symptoms often develop gradually. Common manifestations include persistent joint pain, swelling, and stiffness in the affected area. Swelling can be pronounced, impacting joint function.
Patients may also report sensations of locking or catching within the joint, along with a feeling of instability. In some instances, especially with diffuse PVNS, hemarthrosis (blood accumulation within the joint) can occur. This bleeding can happen even with minimal or no trauma to the joint. Symptoms can fluctuate, appearing and subsiding.
Treatment Approaches for PVNS
Treatment for PVNS typically involves surgical intervention. The primary aim is to remove the overgrown and damaged joint lining, along with any resulting masses. This procedure, known as a synovectomy, helps alleviate pain and restore joint function.
Following surgery, patients require follow-up care to monitor the joint’s recovery. While often effective, PVNS can recur in some cases, necessitating ongoing observation. The specific surgical approach depends on the form of PVNS and the affected joint.