Pannus and Rheumatoid Arthritis (RA): The Basics

Medically Reviewed by Zilpah Sheikh, MD on April 17, 2024
6 min read

Pannus is an abnormal, extra layer of tissue in your joints that can cause pain, swelling, and damage to your bones, cartilage, and other tissue. It most often results from rheumatoid arthritis (RA), which is an inflammatory disease that affects your joints. With an inflammatory disease, your immune system attacks healthy cells in your body and causes inflammation, or painful swelling. Other inflammatory diseases also may cause pannus.


A delicate membrane or tissue called the synovium lines each joint in your body. It connects to cartilage, the soft, spongy material at the ends of your bones that helps protect them.

In a healthy joint, the synovium lubricates the joint, helping it move smoothly. It also supplies nutrients and even helps make building materials like collagen. But in some people with RA, it can start to grow too much.

This extra synovial tissue can thicken and grow into areas that it shouldn’t. Special immune system cells (T and B lymphocytes, macrophages, mast cells, and others) make up much of these new clumps of tissue. Your doctor might call them pannus formations.

This type of growth (also sometimes known as synovial hypertrophy) can cause stiff joints. If it goes on for too long, it can damage bone, cartilage, and other tissue.

Pannus can grow quickly, similar to the ways tumors grow. But pannus isn’t cancer and can’t spread to other areas of the body.


Rheumatoid arthritis causes the extra tissue growth in your joints. Serious pannus formations develop only if you don’t get treatment for RA or if your doctor can’t find a way to treat it effectively. This is rare.

But what is the cause of rheumatoid arthritis?

Scientists know it happens when your immune system starts to misfire and attack your joints, but they don’t yet know why this happens in the first place.

Your genes seem to play a role, but just because you have the genes that make RA more likely doesn’t mean you’ll get the disease. Certain things in the environment -- smoking, for example -- also can lead to RA. But not everyone who smokes or lives around smokers gets RA, either. And some people get RA without the genes or any known environmental factors.

Scientists continue to study the roots of this autoimmune disease.

The symptoms are a lot like those of rheumatoid arthritis itself: pain, swelling, stiffness, and tenderness in a joint, often on both sides of your body (such as both knees, both wrists, or both thumbs).

With pannus formations, the pain can be severe. The swelling can be bad enough that the joint looks misshapen, even to the average person.

But if you have RA and get regular checkups for it, you’re unlikely to get the pannus formations that can damage your joints. This is largely due to advances in the early diagnosis and treatment of rheumatoid arthritis.



Usually, your doctor will diagnose you with RA before pannus can even start, and long before it can cause any obvious harm. But if you’ve had RA for a long time and your medication hasn’t kept the disease in check, you could get pannus formations.

To find out for sure whether your joint is just swollen or is really damaged or deformed, your doctor will do imaging tests like X-rays, an MRI, or a CT scan. These images can show the pannus formations and whether they’re large enough to eat away bone and cartilage or damage your joint.

Your doctor will treat pannus largely the same way they would rheumatoid arthritis. The right treatment depends on your lifestyle as well as where in your body the pannus formation is. 

Because pannus is a sign of more serious, longstanding RA, your doctor might skip the standard treatments with over-the-counter nonsteroidal anti-inflammatory drugs like ibuprofen and naproxen and start you on prescription medications. What you take will depend on your symptoms, your previous treatments, and how long you’ve had RA. Your doctor may prescribe:

It can take 3 months or longer before you see improvement with DMARDs or biologics. But they can be very effective. Often they completely reverse the growth of pannus formations. But in more serious cases, where the formations have damaged bone or cartilage, it isn’t usually possible to repair the damage with medication.

Talk to your doctor about the best approach for you.


If your pannus doesn’t reverse, or if it continues to grow, surgery may be an option. Synovectomy is a surgery that removes inflamed synovium, which can help relieve pain and improve how your joint functions. 

An orthopedic surgeon can do a synovectomy in two different ways: as an open surgery or using an arthroscope, which inserts a tiny camera and instruments through small cuts in your skin. 

Complications of pannus may include damage to your:

  • Bones
  • Cartilage
  • Ligaments

When the joints affected by pannus lose their shape and alignment, that can cause deformities in your joints, such as your finger joints bending abnormally. Severe deformities might make the joint stop functioning.

Pannus can grow quickly. Although pannus sometimes has been considered irreversible, it can be reversed with treatment for RA.

Doctors typically treat RA aggressively when it is in its early stages, before it gets more severe. Studies have shown that when early, aggressive treatment is used, there may be less joint damage.

Getting the proper treatment for rheumatoid arthritis can help prevent pannus from forming because it can limit the inflammation in your body. So it’s important for your doctor to monitor your RA often to make sure you’re getting the treatment you need.

Pannus is an extra layer of tissue in your joints, and it’s caused by rheumatoid arthritis or other inflammatory diseases. It can damage your joints and bones, but getting treatment for your RA can prevent that. Early treatment is important, so if you have RA, make sure you are getting checkups. Treatment for pannus can include medication and surgery to remove pannus.

  • What does pannus look like? If you could see inside your body, pannus would look like an extra substance that has built up in and around your joint.
  • What is pannus a feature of? Pannus is a feature of rheumatoid arthritis.
  • Does pannus go away? Some treatments can reduce inflammation and help limit pannus. And surgery can remove pannus.