What Is Felty Syndrome?

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Rheumatoid arthritis (RA) is associated with a rare disorder called Felty syndrome (FS). FS is known for causing an enlarged spleen and exceptionally low white blood cell counts. FS can be a very painful condition and lead to serious infections.

According to a 2014 report in The Open Rheumatology Journal, it is estimated that 1–3% of people with RA are affected by FS. Felty syndrome is more common in people who have had RA for 10 or more years.

Here is what you need to know about Felty syndrome, including symptoms, causes, diagnosis, and treatment. It is also sometime's denoted Felty's syndrome.

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Felty Syndrome Symptoms

RA is an autoimmune disease—a disease where your own immune system attacks healthy joints and tissues throughout the body. And the signs of Felty syndrome can be similar to those of RA, which might make it harder for your doctor to diagnose FS.

Symptoms of Felty syndrome include:

  • Anemia (not enough healthy blood cells to move oxygen throughout the body)
  • Burning eyes and eye discharge
  • Chronic fatigue
  • Fever
  • Loss of appetite or weight loss
  • Pale skin
  • Sores or brown spots on the legs
  • Stiff, swollen, and painful joints, especially in the hands, feet, or arms
  • Repeat, chronic infections, especially of the lungs, blood, and urinary tract
  • Swollen lymph nodes, usually in the neck

People with FS will also have a swollen and enlarged spleen, a condition called splenomegaly. Your spleen is the fist-sized organ located just behind your left ribs. It spleen is responsible for controlling the number of white blood cells in the body and for helping your immune system fight off infections.

If your spleen is enlarged, you may feel dull pain on the left side of your abdomen or in your back. You might also feel full soon after you start eating because the enlarged spleen is pressing against your stomach. It is possible to not experience any symptoms with an enlarged spleen.

Additional symptoms of Felty syndrome may include ulcers, discolored skin areas, or an enlarged liver. Symptom type and frequency will vary from person to person, depending on the severity of the condition.

FS is also associated with vasculitis (blood vessel inflammation), and thrombocytopenia, which causes a decrease in the circulating blood-clotting platelets. Both of these conditions are complications of unmanaged RA and FS.

The most serious complications of FS are severe and recurrent bacterial infections. Other complications include severe anemia and hemorrhage (bleeding) from severe thrombocytopenia.

Causes

The cause of FS is unknown. Some experts think it might be an autoimmune disease with the same genetic component associated with other autoimmune conditions, which are inherited in an autosomal dominant manner.

Autosomal dominant inherited conditions require only one copy of the mutated gene to trigger a specific disease. But there hasn't been enough clinical evidence to confirm that FS might have an inheritance pattern.

Most people who develop Felty’s do not have a family history of the condition, and there have only been a few, rare reports that could indicate FS might be familial (occurring in families).

Other possible risk factors for FS may include:

  • Rheumatoid factor (RF) positivity: RF positivity affects 70–90% of people with RA. RF is an autoantibody common in people with RA and autoimmune diseases although having an RF doesn’t mean someone will go on to develop RA. People with a negative RF can still have RA. Higher RF levels have been linked to more severe RA symptoms and faster disease progression.
  • Longstanding, severe rheumatoid arthritis: While RA puts you at greater risk to develop Felty’s, not everyone with RA will develop the condition.
  • Aggressive and erosive inflammation of the synovial membrane (the tissue lining the joints)
  • HLA-DR4 positivity: This is a gene marker that has been found to increase RA risk and severity.
  • Having extra-articular RA manifestations like vasculitis or pericarditis (inflammation of the pericardium—the thin saclike membrane surrounding the heart)

Diagnosis

There can no single test that can confirm Felty syndrome. A diagnosis can be made based on the presence of RA, an enlarged spleen, and an unusually low white blood cell count.

If your doctor thinks your spleen is enlarged, they will feel around your stomach to confirm swelling. They will also request imaging, including magnetic resonance imaging (MRI) and/or computerized tomography (CT), to confirm the spleen is swollen and enlarged.

Felty syndrome is associated with leukopenia or a low white blood cell count. White blood cells are called leukocytes and they help the body fight infection and other diseases. Blood work for Felty syndrome will include a complete blood cell count.

Your doctor may also request a blood lab test to check for neutropenia, or exceptionally low neutrophils white blood cells. These blood cells help you to fight off bacterial infections.

Treatment

Treatment for Felty syndrome involves controlling RA and treating neutropenia to prevent serious infections. Most people with FS are mainly treated with immunosuppressants—drugs that inhibit the activity of the immune system. This includes methotrexate and glucocorticoids.

Other drugs that can treat FS include biologic therapies to calm down your immune system like Actemra (tocilizumab) and Rituxan (rituximab). Biologic therapies for Felty’s might be given by IV (through a vein).

Other therapies for Felty’s may include drugs to stimulate white blood cells, including granulocyte colony-stimulating factor injections. These injections will help to increase the number of white blood cells so you can better fight off infection.

Your doctor may also recommend managing pain with over the counter pain relievers or a heating pad. They can also tell you how to balance your rest and activity levels so as to manage pain and other FS symptoms.

Surgery

If FS is severe or treatments don’t work, your doctor will recommend a splenectomy (spleen removal). A splenectomy could mean a return to normal red and white blood cell counts and lowered infection risk. It is very possible to live without a spleen as your liver will take over most of the functions of the spleen.  

Potential complications of splenectomy include the usual risks of surgery, including bleeding, infection, or injury to nearby organs.

A long-term risk associated with a splenectomy is an overwhelming post-splenectomy infection that could lead to meningitis or sepsis. You will be monitored for several months after spleen removal and given antibiotics to prevent infection.

You will need pneumococcal, influenza type B, and meningococcal vaccines after spleen removal and boosters every five years to reduce your risk for these severe infections. You should get a flu shot every year. If you get sick and have a high fever, contact your doctor immediately to get treated in case you have an infection.

A Word From Verywell

If you have RA and develop signs of Felty syndrome, get in touch with your doctor. Early diagnosis and treatment are vital to successfully managing the condition and reducing your risk for severe complications. 

Even with treatment, you will need to be vigilant if you experience recurring infections with FS, Do what you can to reduce your risk for infection, including avoiding injury, getting a yearly flu shot, avoiding crowded areas during flu season, and washing hands thoroughly and often. 

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