What Is Felty Syndrome?

Introduction 

Felty syndrome is a clinical manifestation of rheumatoid arthritis reported to occur in about 3% of patients with rheumatoid arthritis. It is an uncommon disorder that results in neutropenia (low neutrophils, a type of immune cell) and enlargement of the spleen. The factors that can lead to low neutrophils are the lack of balance between the production of neutrophils in the bone marrow and the increased rate of their destruction in the blood.¹  

Brief overview of immune system disorders 

Immune disorders happen when the immune system that protects your body against infections and diseases begins to attack the body’s organs and tissues. They are collectively referred to as auto-immune disorders. The three most common autoimmune disorders are ​rheumatoid arthritis, systemic lupus erythematosus and type​ ​1 diabetes. Rheumatoid arthritis is characterised by painful and inflammatory joints which subsequently affect the heart, the eyes, the kidneys and the lungs.² This disease has no cure; treatments only tend to manage symptoms and prevent them from progressing. 

Understanding felty syndrome  

If you have been diagnosed with rheumatoid arthritis, on rare occasions, you might experience Felty syndrome. It has been reported that it takes an average of 16 years after diagnosis with rheumatoid arthritis to start showing symptoms of Felty syndrome.¹ However, in some instances, you might experience Felty syndrome before being diagnosed with rheumatoid arthritis. 

Even though the exact cause of the disease is not known, and patients do not often show symptoms, increased susceptibility to infections as a rheumatoid arthritis patient might be an indication of Felty syndrome. This could be due to the role neutrophils and the spleen play in maintaining immunity.³  

Symptoms and diagnosis  

Common signs and symptoms of Felty syndrome 

As Felty syndrome is a clinical manifestation of rheumatoid arthritis, their symptoms seem to be the same. The common symptoms you might experience include:³

• Abdominal pain 
• Skin hyperpigmentation 
• Pleurisy (inflammation around the lungs)
• Leg ulcers 
• Portal hypertension (high blood pressure in the vein that carries blood from the digestive system to the liver)
• Eyelid necrosis (tissue death)
• Inflamed blood vessels 
• Weight loss
• Liver cirrhosis (scarring) 
• Polyarticular joint pain (pain in multiple joints)
• Increased susceptibility to bacterial infections 

Challenges in diagnosing Felty syndrome 

Felty syndrome is usually diagnosed by a clinical evaluation of your medical history and by checking for the predisposing factors associated with the condition like rheumatoid arthritis and other auto-immune diseases. However, since Felty syndrome could be asymptomatic and is very rare, it can be difficult to diagnose sometimes.⁴ 

Importance of medical evaluation and blood tests 

Diagnosing Felty syndrome involves being evaluated through different tests like:¹ 

• A full blood count test is needed to detect a low neutrophil count. Under 2000, neutrophils per microliter are regarded as low. Anaemia and thrombocytopenia from an enlarged spleen could also be detected during the test. Many rheumatoid arthritis patients have anaemia from chronic inflammation. 
• Histological examination of spleen tissues 
• Scans of joints to detect joint damage

• Ultrasound of the spleen to detect enlargement 
• Laboratory tests for rheumatoid arthritis  

Causes and risk factors  

Role of genetics and immune system dysfunction  

The actual cause of Felty syndrome is not specific, but research has linked it to the presence of excess HLA DR4 homozygosity, a genetic marker which usually indicates the presence of rheumatoid arthritis. This was reported to be present in about 90% of Felty syndrome patients, compared to a 60-70% range seen in rheumatoid arthritis patients. 

Environmental factors and the use of immunosuppressive drugs for treating rheumatoid arthritis have also been identified as potential risk factors. A family history of rheumatoid arthritis also predisposes you to having the condition.³ 

Complications 

Due to neutropenia, one of the significant complications of Felty syndrome is the increased susceptibility to recurring infections, especially of the skin and respiratory system. Other complications include splenic sequestration-induced anaemia and severe thrombocytopenia-induced haemorrhage (bleeding).¹ Patients are also at risk of infections after surgical removal of the spleen (splenectomy), which can sometimes be fatal. Portal hypertension could also cause haemorrhage of the gastrointestinal tract. Therefore, experiencing both Felty syndrome and rheumatoid arthritis at the same time might have a negative effect on your overall well-being if not properly monitored by your physician.¹ 

Treatment and management  

Approaches to managing Felty syndrome symptoms  

To treat Felty syndrome, your physician would have to treat the underlying condition, which is rheumatoid arthritis and manage neutropenia to prevent recurring infections.  

The treatment target would be to achieve a granulocyte count of over 2000 per microliter.¹ 

If you have neutropenia without signs of infection, there would not be any serious treatment given to you. However, as a rheumatoid arthritis patient, the presence of neutropenia can be used to determine or adjust the amount of disease-modifying anti-rheumatic medications (DMARDs) you are eligible for.¹ The reduction in your neutrophil count after rheumatoid arthritis therapy shows that Felty syndrome is present. 

If you have neutropenia, you would be required to undertake routine immunisations, proper dental and oral hygiene checks, along with other forms of care. Broad-spectrum antibiotics can also be used by your physician to treat infections properly. Consultations with infectious disease experts might be helpful too.

Immunosuppressive medications and their role 

There are insufficient randomised control trial studies ​for the treatment of Felty​ syndrome. Studies available are observational.  

• A ​low dose​ of ​methotrexate is considered​ a ​first-line treatment for​ Felty syndrome, as this is expected to improve your neutrophil count and prevent infections⁵ 
• Leflunomide is also used to prevent permanent damage and reduce inflammation⁶ 
• Cyclosporine is usually given when there seems to be no improvement with methotrexate⁷ 
• Rituximab also sustains neutrophil count⁸  
• Glucocorticoids like methylprednisolone have also shown a positive improvement in neutrophil levels; however, prolonged use is not advised due to its immunosuppressive effects⁹  
• For patients with no improvement following the suggested therapies, splenectomy is usually a suggested treatment option¹⁰ 

Prognosis and long-term outlook  

There is a lack of data on the prognosis of Felty syndrome. The development of advanced treatments like granulocyte colony-stimulating factor (G-CSF) in treating chronic neutropenia has positively impacted the mortality rate, which used to be 36%.¹ Treatment of chronic neutropenia has also reduced the need for splenectomy in patients with Felty syndrome. Even though it is a rare condition, as a rheumatoid arthritis patient, it is important to have routine medical check-ups and blood tests because Felty syndrome could be asymptomatic.¹ Recurring infections should prompt you to visit your healthcare provider without delay.  

Summary  

Felty syndrome is a rare condition that occurs in some rheumatoid arthritis patients. It is characterised by an enlarged spleen and low neutrophil count. This means the immune system has lost its defensive ability and can no longer protect you against infections. If, as a rheumatoid arthritis patient, you start experiencing frequent infections, you should visit your healthcare provider for a medical checkup and quick diagnosis to curb the life-threatening effects of the condition on your overall health. Although there is limited research on Felty syndrome, the advancement in treatment and reduction in mortality rate over the years is a sign of hope.