Felty Syndrome

What is Felty syndrome?

Felty syndrome is a triad of three conditions that occur together:

• Rheumatoid arthritis.
• Neutropenia.
• Splenomegaly.

It usually starts with rheumatoid arthritis (RA), and the other two conditions occur as complications of RA. Healthcare providers call these “extra-articular manifestations,” meaning they’re manifestations of arthritis that occur outside of your joints. The same inflammatory and autoimmune processes cause them. Extra-articular manifestations are common with RA, but Felty syndrome is relatively rare.

How does Felty syndrome affect me?

Felty syndrome begins with rheumatoid arthritis, which is painful inflammation in the lining of your joints. When neutropenia and splenomegaly appear, they affect your immunity. Neutropenia is low levels of a certain type of white blood cell called neutrophils, which play an important role in protecting you against infections. Splenomegaly is an enlarged spleen, which can contribute to neutropenia.

How common is Felty syndrome?

Around 2% of people with rheumatoid arthritis develop Felty syndrome. Like RA, Felty syndrome is three times more common in women and people assigned female at birth (AFAB) than in men and people assigned male at birth (AMAB). Those who develop Felty syndrome with RA are almost always seropositive, meaning they test positive for the rheumatoid factor antibody. Those who are seronegative rarely develop Felty syndrome.

What are the symptoms of Felty syndrome?

Most of the time, symptoms of rheumatoid arthritis appear before other symptoms. These include:

• Joint pain.
• Joint swelling.
• Joint stiffness.

Some people develop extra-articular manifestations of RA, with additional symptoms, including:

• Rheumatoid nodules, firm lumps under your skin near your joints.
• Swollen lymph nodes in your neck or under your arms.
• Swollen liver, which might be sore or palpable to touch.
• Dry eyes and mouth (Sjogren’s syndrome).
• Swelling and redness in your eyes (episcleritis).
• Skin ulcers (sores), especially in your legs.
• Signs of bleeding under the skin.
• Swelling in your lungs, causing shortness of breath.
• Swelling around your heart, causing chest pain.
• Fever.
• Fatigue and malaise.
• Loss of appetite or unexplained weight loss.

Felty syndrome appears with additional symptoms — occasionally, before RA symptoms — including:

• Frequent, persistent infections, like colds, stomach bugs and skin infections.
• Swollen spleen, which may be sore or palpable to touch.
• Abnormal skin discolorations (patches).

Occasionally, Felty syndrome is diagnosed without any symptoms. Blood tests and imaging tests may show signs of rheumatoid arthritis, neutropenia and splenomegaly before you’ve noticed symptoms.

What is the average age of onset?

Felty syndrome typically develops later in life, between the ages of 50 and 70. Most people have symptoms of progressive rheumatoid arthritis for 10 to 15 years before Felty syndrome appears.

What causes Felty syndrome?

Rheumatoid arthritis is an autoimmune disease, and most scientists view Felty syndrome as a severe complication of RA. In autoimmune disease, your immune system mistakes some parts of your own body as foreign and attacks these parts with inflammation. Sometimes, it produces antibodies that bind to certain proteins in your body and tag them for removal. In this way, antibodies can accelerate inflammation.

Autoimmune antibodies aren’t always present with RA, but they’re always present with Felty syndrome. They’re also associated with more severe RA and more extra-articular manifestations in general. RA involving antibodies is called “seropositive” RA. Evidence suggests that both seropositive RA and Felty syndrome are related to certain genetic factors, which means they might be partly hereditary.

How does rheumatoid arthritis lead to neutropenia and splenomegaly?

Neutropenia generally happens in one of two ways: Either your bone marrow fails to produce enough neutrophils or your body removes the neutrophils you have. In Felty syndrome, both can occur. Autoimmune processes can interfere with your bone marrow’s production of neutrophils and destroy some of the neutrophils you have. An enlarged spleen may also remove some of your neutrophils.

Your spleen has the job of filtering and removing expired blood cells from your blood. When it grows too large, it can become hyperactive and remove too many blood cells. Splenomegaly sometimes occurs with rheumatoid arthritis, for reasons that aren’t always clear. It can occur without neutropenia and Felty syndrome, and Felty syndrome can also occur without splenomegaly, although it’s uncommon.

What are the serious complications of Felty syndrome?

As Felty syndrome affects your immunity, it can make you more vulnerable to persistent and severe infections. Common illnesses that you would normally be able to fight off may now become chronic and in some cases, life-threatening. Bacterial infections that spread uncontrollably can lead to sepsis. People with Felty syndrome are also at greater-than-average risk of developing certain cancers, like lymphoma.

How is Felty syndrome diagnosed?

Healthcare providers diagnose Felty syndrome when medical tests show evidence of rheumatoid arthritis, neutropenia and splenomegaly. (Occasionally, they diagnose it without splenomegaly.)

Tests typically include:

• Blood tests, including a complete blood count to measure your neutrophils.
• X-rays of your joints to look for evidence of arthritis.
• Imaging of your spleen, such as an ultrasound or CT scan.
• Bone marrow biopsy to help rule out other diseases.

What is the treatment for Felty syndrome?

Treatment for Felty syndrome includes:

• Managing the underlying rheumatoid arthritis.
• Treating neutropenia directly when it’s too severe.
• Preventing and treating infections.

Felty syndrome can be a consequence of untreated or ineffectively treated rheumatoid arthritis. And for many people with Felty syndrome, neutropenia improves when RA does. Healthcare providers focus on selecting effective disease-modifying antirheumatic drugs (DMARDs) for RA while avoiding immunosuppressants, drugs that suppress your immune system, as much as possible.

Possible DMARDs for Felty syndrome include:

• Methotrexate with folic acid (to offset anti-folate side effects).
• Abatacept.
• Rituximab.
• Leflunomide.

If DMARDs fail to improve your neutropenia, or if your neutropenia is too severe or you have an active infection, your provider might try other treatments to boost your neutrophils. These might include:

• G-CSF (granulocyte colony-stimulating factor).
• A short course of corticosteroids.
• Splenectomy (removing your overactive spleen).

Healthcare providers also take extra measures to protect you against infections, especially when your treatment plan affects your immunity. They might recommend preventive treatments, including:

• Taking broad-spectrum antibiotics.
• Getting vaccinations.
• Taking extra care with oral hygiene.

If you get an infection with Felty syndrome, healthcare providers take it very seriously. You should always seek treatment for it right away. Your provider will prescribe strong medications for it.

What is the life expectancy or mortality rate with Felty syndrome?

There aren’t any current statistics on life expectancy or mortality with Felty syndrome. But in general, the treatment options have improved greatly in recent years, and it’s very likely one of them will work. The biggest mortality risk with Felty syndrome is still from severe infections. So, preventive measures you take to protect yourself from infections can make a real difference in your long-term prognosis.