Pigmented Villonodular Synovitis

Pigmented Villonodular Synovitis Definition

Pigmented villonodular synovitis (PVNS) is a disease of the joints characterized by inflammations and overgrowth of joint lining. The condition generally affects a person’s knee or hip area, but can also be seen in other parts of the body as well, such as ankle, elbow, shoulder, hand or foot. It causes swelling and growth of the joint lining known as synovium. The growth adversely affects the bone placed next to a joint. Extra fluid is released by the lining that causes swelling and makes movements painful.

The condition was described distinctly by Charles J. Sutro, H.L. Jafe and L. Lichtenstein in the year 1941.

Pigmented Villonodular Synovitis Epidemiology

PVNS is an idiopathic condition; i.e. it is not found to run in a family or is caused by certain activities or jobs. The condition affects more males than females, although localized PVNS is more predominantly found in women. The condition is rare, affecting only 2 individuals in per million populations. The localized form occurs in almost 9 instances per million populations. Although both pediatric as well as geriatric patients are known to be affected by this disorder, it is mostly common among people aged between 20 and 50 years.

Pigmented Villonodular Synovitis Classification

PVNS can be of two types: localized and diffuse. The diffuse variant of the disorder affects the whole synovium and it generally develops in the large joints like the hip or knee. It is more destructive out of the two with the treatment being relatively more challenging.

The localized or nodular form of PVNS is rather less prevalent than the other variant and mostly occurs in the smaller joints, for example, in one’s hands and feet. It generally begins as a large-sized benign tumor that develops on tendon sheaths of a joint. The tumor can damage the surrounding tissues and bones as it grows larger. Compared to the diffuse form, it is much easier to treat localized PVNS.

Pigmented Villonodular Synovitis Causes

The exact factors responsible for the development of this condition are not known. Although certain genetic changes have been identified in relation to PVNS, the evidence to suggest a genetic link is not conclusive yet.

Pigmented Villonodular Synovitis Symptoms

The symptoms of PVNS generally manifest themselves initially as sudden, unexplained joint swellings accompanied by pain. The joint swellings are at first disproportionate to the extent of pain felt by the patient. Progression of the disorder is characterized by reduced motion, increased pain and stiffness or locking of the particular joint. Localized PVNS frequently manifests initially as painless, slow-growing palpable mass which then progresses to the other symptoms commonly associated with the condition. The swelling often feels warm to touch. A popping feeling might accompany movement of the joint. Recurrent episodes of atraumatic hemarthosis is a major hallmark of this disorder. The symptoms develop gradually and may occur sporadically.

Pigmented Villonodular Synovitis Diagnosis

The diagnosis of PVNS can be difficult and may not be successfully accomplished for years due to the presence of nonspecific symptoms or their general paucity. In order to find out if the patient is affected by PVNS, a doctor will first conduct a thorough examination of the joint and consider alternate probabilities. He or she will then recommend the following diagnostic tests to make sure that the patient has PVNS:

  • X-rays
  • Biopsies
  • Arthroscopy
  • Radiographs
  • Joint Aspiration Tests
  • Computer Tomography (CT) Scans
  • Magnetic resonance imaging (MRI) Scans

Findings of Advanced Imaging Tests

The radiological appearance of PVNS depends on the affected location. A nodule that has developed in the hand might show signs of soft tissue swelling along with bone erosion on a plain x-ray. Cystic erosion accompanied by sclerotic margins can be found on either sides of the affected joint. A soft tissue mass may be noticed on the knee whereas cysts or bone erosion may be observed in tighter joints such as the hip, ankle, wrist or elbow. Joint space is commonly preserved and signs of effusion might be present. Signs of synovial proliferation can be easily noticed in the imaging tests. CT scans can pick up hemosiderin and demonstrate extent of synovial involvement and also the presence of cysts and bone erosion. Hemosiderin appears low or absent on both the T1-T2 weighted images.


Diffuse PVNS is characterized by a tan-colored mass of villi and numerous folds of synovium. A lesion may either be sessile or can include several pedunculated nodules. There is a good chance of bony invasion through joint capsule. The localized PVNS can be described as a pedunculated firm nodule. Synovial cell hyperplasia occurs on both the surface as well as below the synovium. Scattered giant cells, foam cells and hemosiderin are also present. The location of polyhedral cells below synovial membrane indicates that the condition may have originated from a fibrohistiocyte.

Pigmented Villonodular Synovitis Differential Diagnosis

A number of bone and joint conditions show signs and symptoms similar to that of pigmented villonodular synovitis. A doctor must differentiate these similar disorders from PVNS while trying to establish a conclusive diagnosis for this condition. The differential diagnoses for PVNS include:

  • Capsulitis
  • Fibromatosis
  • Joint effusion
  • Osteoarthritis
  • Septic arthritis
  • Psoriatic arthritis
  • Synovial sarcoma
  • Siderotic synovitis
  • Avascular necrosis
  • Soft-tissue sarcoma
  • Lipoma arborescens
  • Rheumatoid arthritis
  • Inflammatory arthritis
  • Hemorrhagic synovitis
  • Hemosiderotic synovitis
  • Synovial chondromatosis
  • Inflammatory arthropathies
  • Systemic lupus erythematosus
  • Malignant or benign bone tumor
  • Pigmented villonodular synovitis

Pigmented Villonodular Synovitis Treatment

Due to the high rates of recurrences and surgical complications in the past, doctors recommended close observation instead of action as long as an operation of total joint replacement became mandatory. However, improved surgical procedures have reduced the risks of complications and recurrence rates to such a degree that surgery is nowadays considered to be the best possible treatment option for people affected by PVNS. A combination of anti-inflammatory medications and muscle-strengthening exercises can help to alleviate pain and swelling for patients who are not the ideal candidates for a surgical treatment.

Once PVNS is confirmed by a biopsy of the affected joint’s synovium, a synovectomy is the treatment of choice for the affected area. The bone lesions that are caused by PVNS are removed which is then followed by bone grafting as per need.

The various surgical methods used for treating PVNS are discussed below:

Open Surgery

For patients having Diffuse PVNS where both front and back portions of the knee are involved, an open surgery is often the ideal form of treatment. In an open surgery, a doctor will get rid of the mass along with the joint lining to treat the condition.


Arthroscopic partial removal of affected joint lining and the mass is the common form of treatment for localized PVNS nowadays. The procedure has a high rate of success as recurrence rates at the same location are very low.

Arthroscopy in combination with Open Surgery

When a major portion of the mass has developed at the back of a knee, the doctor may choose to combine two forms of treatment procedures to manage the condition. The back portion of the knee can be treated with an open surgery that removes the mass and the joint lining, whereas the front portion of the knee is treated with an arthroscopic removal of joint lining. The magnitude of the surgery is reduced by this combined method which allows for a relatively easier recovery. Although the recurrence rates are higher with patients having Diffuse PVNS, it is possible to minimize the risks of recurrence with proper surgical techniques.

Total Joint Replacement

Extensive joint destruction can occur at the end stages of an advanced PVNS. In such cases, total joint replacement is the best way to erase pain and restore joint health.

Radiation Therapy

Radiation therapy is used for patients who have not responded as expected to the standard surgical methods of treating PVNS. This form of treatment is especially used in cases of diffuse PVNS that involves major tendon, nerve, vascular lesions or structures that recur after a surgery.

Pigmented Villonodular Synovitis Complications

PVNS can be locally aggressive and metastasize to the surrounding tissues, thereby causing tissue damage and bone erosion. If ignored or not treated early, the condition can spread to the other areas outside the affected joint.

Pigmented Villonodular Synovitis Pictures

Here are some images that give you a clearer idea as to the nature of this condition.

Picture of Pigmented Villonodular Synovitis

Picture 1 – Pigmented Villonodular Synovitis

 Image of Pigmented Villonodular Synovitis

Picture 2 – Pigmented Villonodular Synovitis Image

Pigmented Villonodular Synovitis Prognosis

Prognosis for PVNS is good with total joint replacement or synovectomy. Although the condition has a high rate of recurrence (45%), a patient might take anti-inflammatory drugs like ibuprofen and naproxen to ease the swelling and pain. For a more complete recovery, surgery needs to be combined with postoperative physical therapy and adequate resting.

One Response

  1. Liz Banfich March 22, 2017

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