What is Felty Syndrome ?

Felty syndrome is a rare autoimmune disorder in which the body’s immune system starts acting against its own body cells due to a variety of reasons. Felty’s syndrome was first described by American physician Augustus Roi Felty in year 1924.¹

Following are three key parameters which helps physicians decide on whether a patient might have Felty’s syndrome or not.

1. History of Rheumatoid Arthritis 

Long standing Rheumatoid Arthritis with severe joint pain, inflammation, presence of joint deformities and reduced mobility.

2. Enlarged spleen 

In physical examination the spleen is found to be enlarged. The spleen is an organ which plays an important role in filtering your blood and fighting infection.

3. Neutropenia

Blood reports indicate low neutrophil (a type of white blood cell) count which can increase incidences of recurrent infections in people with Felty’s syndrome.

So in short, if you have a history of long-standing rheumatoid arthritis, your spleen is enlarged, and your blood reports are showing low count of neutrophils then it raises a possibility of Felty’s syndrome.²

What causes Felty’s Syndrome ?

The exact cause of Felty’s syndrome is unknown but the following factors are thought to be contribute to Felty’s syndrome

1. Autoimmune dysfunction 

 Due to variety of reasons the body's immune system dysfunctions and starts acting against its own body cells  in this case against joints, spleen and neutrophils.³

2. Genetics 

People with certain genetic markers like HLA-DR4 are more likely to develop rheumatoid arthritis first and Felty’s syndrome as an extension of it.⁴

3. Rheumatoid Arthritis 

In long standing rheumatoid arthritis, inflammation becomes chronic and this chronic inflammation disturbs normal functioning of the immune system affecting the spleen and neutrophils. This leads to splenomegaly and neutropenia along with joint symptoms which are already present.

4. Environmental factors

The role of environmental factors is still unclear but external triggers in your environment can trigger your immune system to act against its own body cells. 

What are the symptoms of Felty’s syndrome?

 The characteristic symptoms seen in Felty’s Syndrome are as follows: ⁵

• Joint pain, swelling, deformities and reduced mobility
• Recurrent infections due to reduced immunity because of low neutrophil count
• Fatigue and tiredness
• Fever
• Weight Loss
• Enlarged spleen

Out of all these symptoms today we are going to focus particularly on joint symptoms that are developed in Felty’s syndrome.

This will help you to better understand the progression and take necessary precautions and  treatment to reduce the discomfort and damage to the joints and improve quality of life.

Which joints are most affected in Felty’s syndrome?

The joints mostly affected are: 

• Knees
• Ankles
• Hips
• Feet
• Elbows
• Shoulders
• Hands
• Wrists

These joints are involved symmetrically, meaning the same joints on both sides of the body are affected.

What Joint symptoms develop in Felty’s syndrome?

Pain 

This is a classic symptom where joint pain is present which often worsens with activity and improves with rest.

Swelling 

Joints show persistent swelling along with redness and the joint surface feels warm to touch.

Stiffness 

Joints become stiff especially in the morning or during prolonged periods of inactivity.

Reduced Mobility 

Due to the pain and swelling the range of joint movements gets limited.

Joint Deformities 

Due to the damage to the joint structure deformities develop over time, such as ulnar deviation (fingers pointing towards the little finger) and swan neck or boutonniere deformities in the fingers.

Other symptoms 

Patients with Felty’s syndrome have other symptoms which include an enlarged spleen, enlarged liver and low neutrophil count.

How do joint symptoms develop and progress in Felty’s syndrome?

In Felty’s Syndrome, there is often an underlying severe form of rheumatoid arthritis  The joint pathophysiology follows the same as that of RA but in a more aggressive form where additional systems apart from joints are also involved. Here's how joint symptoms get manifested in Felty’s Syndrome:

1. Inflammation 

The membrane lining the joints is called the synovial membrane, and in Felty’s syndrome this synovial membrane gets inflamed resulting in Synovitis.

2. Cartilage damage

This inflamed membrane releases cytokines and enzymes which start damaging the cartilage in the joint. This damaged cartilage causes loss of cushioning between the bones and the joint space also starts narrowing.

3. Formation of pannus

When this inflammation lasts for a long time,  granulation tissue starts forming. Although granular tissue is vital for the body's normal healing mechanism, here in Felty’s syndrome, this granulation tissue formation becomes pathological and is referred to as Pannus. This pannus starts invading surrounding cartilage and bones aggressively leading to its destruction.

4. Bone erosion

Due to invasion of pannus the bone surface starts showing small holes or defects which are visible in imaging studies.

5. Deformities 

Due to the damage to the bones and cartilage and overall joint structure, the normal range of joint motions gets reduced resulting in mobility reduction impacting  normal day to day activities.

Diagnosis of Felty Syndrome

Medical history and physical examination

• Patients typically have a history of rheumatoid arthritis with  joint pain, swelling and joint deformation taking place
• Joint assessment tools and scoring systems tell the condition and extent of damage of joints

Laboratory tests

• Rheumatoid factor (RF) and Anti-citrullinated protein antibodies (ACPA): These are often found positive in majority of patients
• Complete blood count (CBC): Neutropenia means neutrophil count is found to be lower than normal
• Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) These are raised indicating presence of  inflammation

Imaging studies

•  X-rays : This shows the extent of joint damage and osteopenia signs
•  Ultrasound : To evaluate spleen size and rule out other causes.
•  MRI
•  Synovial fluid analysis
•  Bone marrow biopsy

Often the diagnosis is confirmed when there is  presence of long-standing rheumatoid arthritis, neutropenia, and splenomegaly, along with peculiar joint findings.

Complications of Felty’s Syndrome

• Due to a reduced number of neutrophils (a type of white blood cell) there is an increased risk of developing secondary infections worsening the joint condition
• Due to chronic inflammation of immune cells, there is an increased risk of developing lymphoma

Treatment for Felty’s Syndrome

For treating joint symptoms in Felty’s syndrome the same treatment line is adopted as that of rheumatoid arthritis. The intention of the treatment is to reduce pain and inflammation of the joints, prevent joints from getting deformed,  preserve joint functions - mobility and overall slowing down disease progression.

Thebelow treatment options are generally recommended: 

For Pain management

• Over the counter painkillers like acetaminophen or topical cream-gels containing NSAIDS are prescribed for localized pain relief
• Corticosteroids like prednisone can be used for a short time to quickly reduce pain and inflammation in times of disease flare up
• Joint injections: For severe pain and inflammation corticosteroids injections can be administered directly into the joints

Biologic agents acting on immune system

• Biologic agents like TNF (Tumor necrosis factor  ) inhibitors, interleukin 6 inhibitors, B cells deleting agents and drugs modulating activity of T cells are used to target specific parts of the immune system which drives inflammation

DMARDS

These are the most important and effective drugs used in treating joint symptoms in Felty’s syndrome : 

• Methotrexate: This slows disease progression and reduces inflammation
• Sulfasalazine and Hydroxychloroquine or Leflunomide is another option which can be used instead or in combination with methotrexate

Antibiotics

Prophylactic antibiotics are prescribed to reduce infections occurring due to reduced neutrophil count.

Surgery

 Surgery in severe cases synovectomy surgery which is removal of inflamed joint lining (synovium)  or joint replacement surgery is recommended. Surgery to remove the spleen might be needed in severe cases to improve neutropenia and reduce infections when all other treatment options fail.

Summary

Felty’s syndrome is a rare autoimmune disorder which is characterized by a triad of symptoms including a history of rheumatoid arthritis, enlarged spleen and reduced neutrophil (a type of WBC) count. The exact cause of Felty’s syndrome is unknown. The characteristic symptoms seen in Felty’s Syndrome are joint pain, swelling, deformities and reduced mobility, recurrent infections due to reduced immunity because of low neutrophil count, fatigue and tiredness, fever, weight Loss and enlarged spleen. The joint manifestations in Felty’s syndrome are like rheumatoid arthritis which includes joint pain, swelling, stiffness, reduced mobility and deformities. There is no cure for Felty’s syndrome, so the treatment is aimed at management of symptoms through the use of analgesic, anti-inflammatory and antibiotic medicines. Use of biologic agents and DMARDs also play a role in management of Felty’ssyndrome.