Villonodular synovitis

A joint disease characterized by inflammation and overgrowth of the synovial membrane

Villonodular synovitis is a rare, benign condition that affects the synovial membrane of joints, tendon sheaths, and bursae. It is characterized by the proliferation of the synovial tissue, leading to swelling and pain in the affected area. This condition is also known as pigmented villonodular synovitis (PVNS) when it involves the joints, and tenosynovial giant cell tumor when it affects the tendon sheaths.

Classification

Villonodular synovitis can be classified into two main types:

• Localized type: This form is usually confined to a specific area within the joint or tendon sheath. It is less aggressive and often presents as a solitary nodule.
• Diffuse type: This form involves a more widespread area of the synovial membrane and is more aggressive, often leading to joint destruction if not treated.

Pathophysiology

The exact cause of villonodular synovitis is not well understood. It is thought to be a neoplastic process, where the synovial cells undergo abnormal proliferation. The condition is characterized by the presence of hemosiderin deposits, multinucleated giant cells, and lipid-laden macrophages within the synovial tissue.

Clinical Presentation

Patients with villonodular synovitis typically present with:

• Joint pain and swelling
• Limited range of motion
• Joint stiffness
• Occasionally, a palpable mass

The knee is the most commonly affected joint, but other joints such as the hip, ankle, and shoulder can also be involved.

Diagnosis

Diagnosis of villonodular synovitis is based on clinical examination, imaging studies, and histological analysis.

• Imaging: Magnetic resonance imaging (MRI) is the preferred method for visualizing the extent of the disease. It typically shows a mass with low to intermediate signal intensity on T1-weighted images and low signal intensity on T2-weighted images due to hemosiderin deposition.
• Histology: A biopsy of the synovial tissue reveals characteristic features such as villous projections, hemosiderin deposits, and multinucleated giant cells.

Treatment

The primary treatment for villonodular synovitis is surgical intervention. Options include:

• Arthroscopic synovectomy: Minimally invasive procedure to remove the affected synovial tissue.
• Open synovectomy: More extensive surgical procedure for diffuse disease.

In some cases, adjuvant therapies such as radiation therapy or targeted therapies may be used to reduce the risk of recurrence.

Prognosis

The prognosis for patients with villonodular synovitis is generally good, especially with early diagnosis and treatment. However, the diffuse form has a higher risk of recurrence and may lead to joint damage if not adequately treated.

Related pages

• Synovial membrane
• Joint disease
• Magnetic resonance imaging
• Arthroscopy