Rheumatoid arthritis (RA) is an autoimmune disorder in which the body’s immune system attacks the joint lining known as the synovium. The condition can cause painful nodules to develop on various parts of the body. These parts of the body include:

  • hands
  • feet
  • wrists
  • elbows
  • ankles
  • areas a person can’t always see, like the lungs

Read on to discover how these nodules form as well as any treatments that may help.

Doctors don’t know exactly why rheumatoid nodules form as a result of rheumatoid arthritis. Typically, a person gets rheumatoid nodules when they’ve had RA for several years. The nodules are made up of the following components:

  • Fibrin. This is a protein that plays a role in blood clotting and can result from tissue damage.
  • Inflammatory cells. Rheumatoid arthritis can cause inflammation in the body that leads to the development of nodules.
  • Dead skin cells. Dead skin cells from proteins in the body can build up in the nodules.

The nodules can closely resemble some other conditions, like epidermoid cysts, olecranon bursitis, and tophi caused by gout.

Rheumatoid arthritis nodules can form in the following areas of the body:

  • back of the heels
  • elbows
  • fingers
  • knuckles
  • lungs

These areas are usually where pressure is placed on the body’s surfaces or around highly used joints, like the elbows and fingers. If a person is confined to bed, they can develop rheumatoid arthritis nodules on:

  • the back of their head
  • heels
  • sacrum
  • other areas of pressure

In rare cases, the nodules can form in other areas, like the eyes, lungs, or vocal cords. These may be difficult for a doctor to identify. But these internal nodules can cause serious side effects, like difficulty breathing, if the nodule is too large in size.

Rheumatoid arthritis nodules can range in size from very small (around 2 millimeters) to larger (around 5 centimeters). They’re usually round in shape, though it’s possible they may have irregular borders.

The nodules typically feel firm to the touch and will usually move when pressed. Sometimes the nodules can form a connection with tissues or tendons underneath the skin and may not move when pressed.

The nodules may be tender to the touch. This usually occurs when a person is experiencing a rheumatoid arthritis flare-up.

Very large nodules or nodules on certain areas can press on nerves or blood vessels. This can cause discomfort and affect a person’s ability to move their hands, feet, and more.

Nodules vary in size, shape, and location on the body. Sometimes a person may have one nodule. Other times they may have a collection of smaller nodules.

Several factors may put you more at risk for developing nodules. These include:

  • Sex. People who have a vagina are significantly more likely to get rheumatoid arthritis than people who have a penis.
  • Time. The longer someone has rheumatoid arthritis, the more likely it is that they’ll eventually develop nodules.
  • Severity. Usually, the more severe a person’s rheumatoid arthritis, the more likely it is that they’ll have nodules.
  • Rheumatoid factor. People with higher levels of rheumatoid factor in their blood are also more likely to get nodules. Rheumatoid factor refers to proteins in the blood that are associated with autoimmune disorders, like rheumatoid arthritis and Sjögren’s disease.
  • Smoking. In addition to severe rheumatoid arthritis, smoking is another risk factor for rheumatoid nodules.
  • Genetics. People with certain genes have a higher risk for developing rheumatoid arthritis.

For some people with RA, nodules may go away. But they may also increase in size instead. It’s impossible to predict how nodules will change over time.

Rheumatoid arthritis nodules don’t always require treatment. But if they cause pain or restrict movement, your doctor may recommend treatments.

Taking medications known as disease-modifying antirheumatic drugs (DMARDs) may help to reduce the size of some rheumatoid nodules.

Doctors have linked another rheumatoid arthritis medication, methotrexate, with increasing the likelihood that nodules will get bigger. This medication suppresses the immune system. If the nodules are problematic, your doctor may recommend switching from methotrexate to another drug, if necessary.

Sometimes injections of corticosteroids can reduce inflammation and treat the rheumatoid nodules. If this doesn’t work, your doctor may recommend surgically removing the nodule or nodules. But the nodules often return after surgical removal.

Rheumatoid nodules don’t always cause complications. But it’s possible that on areas of greater pressure, like the feet, the skin over the nodules can become irritated or infected. The results can be redness, swelling, and warmth at the nodules.

Infected nodules require medical attention. Antibiotics may be required to treat a nodule infection.

See your doctor if you have severe or worsening pain in any nodules you might have or the nodules are severely affecting your ability to move.

Nodules on the bottom of the feet may also make it difficult to walk, cause gait abnormalities, or shift stress to other joints, leading to knee, hip, or low back pain.

Rheumatoid arthritis nodules can range from annoying to painful. While they don’t usually require treatment, you can talk with your doctor if your symptoms start to become painful or you’re having difficulty with mobility.