The cause of Felty's syndrome is unknown, but it has been found to be more common in those with chronic rheumatoid arthritis. Some patients have Human Leukocytic Antigen (HLA-DR4) in their serum. This syndrome is mostly present in people having extra articular manifestations of rheumatoid arthritis. People with this syndrome are at risk of infection because they have a low white blood cell count.
This condition affects less than 1% of patients with rheumatoid arthritis. The presence of three conditions: rheumatoid arthritis, an enlarged spleen (splenomegaly), and an abnormally low white blood cell count are indications that Felty's syndrome is possibly occurring. This condition as a whole is difficult to diagnose due to its complexity given a combination of disorders. It is commonly overlooked or misdiagnosed as other conditions (e. G., leukemia, systemic lupus erythrematosus) because of the rarity and lack of good understanding about it. An acronym can be used to make recognizing this disease somewhat easier:
S: Splenomegaly.
A: Anemia.
N: Neutropenia.
T: Thrombocytopenia.
A: Arthritis (rheumatoid).
Conditions of the Blood => A complete blood count (CBC) can be done to diagnose anemia (normochromic, normocytic), thrombocytopenia, and neutropenia. Abnormal liver function tests are commonly used to help in diagnosis as the spleen and liver are strongly affected by one another.
Splenomegaly => If rheumatoid arthritis is present and other symptoms occur that are not commonly found within RA itself, such as a palpable spleen, further testing should be done. A palpable spleen is not always a clinical significance, therefore CT scan, MRI, or ultrasound can be administered in order to help diagnose the condition. According to Poulin et al, dimensional guidelines for diagnosing splenomegaly are as follows:
- Moderate if the largest dimension is 11 – 20 cm
- Severe if the largest dimension is greater than 20 c.
Rheumatoid Arthritis => RA in patients with Felty's syndrome is chronic (after 10 – 15 years), and presents with increased severity along with extra articular manifestations. RA can be mistaken for other conditions such as gout if not clinically diagnosed. Diagnosis can be confirmed by use of X-rays or synovial fluid analysis.
The symptoms of Felty's syndrome are similar to those of rheumatoid arthritis. Patients suffer from painful, stiff, and swollen joints, most commonly in the joints of the hands, feet, and arms. In some affected individuals, Felty's syndrome may develop during a period when the symptoms and physical findings associated with rheumatoid arthritis have subsided or are not present; in this case, Felty's syndrome may remain undiagnosed. In more rare instances, the development of Felty's syndrome may precede the development of the symptoms and physical findings associated with rheumatoid arthritis.
Felty's syndrome is also characterized by an abnormally enlarged spleen (splenomegaly) and abnormally low levels of certain white blood cells (neutropenia). As a result of neutropenia, affected individuals are increasingly susceptible to certain infections. Keratoconjunctivitis sicca may occur due to secondary Sjorgen's syndrome. Individuals with Felty's syndrome may also experience fever, weight loss, and/or fatigue. In some cases, affected individuals may have discoloration (abnormal brown pigmentation) of the skin, particularly of the leg, sores (ulcers) on the lower leg, and/or an abnormally large liver (hepatomegaly). In addition, affected individuals may have abnormally low levels of circulating red blood cells (anemia), a decrease in circulating blood platelets that assist in blood clotting functions (thrombocytopenia), abnormal liver function tests and/or inflammation of the blood vessels (vasculitis).