Feltys Syndrome ICD-10: M05.0
Felty's syndrome is a complication of arthritis (rheumatoid arthritis, RA). The condition is characterized by a low number of white blood cells (leukopenia with neutropenia) and enlarged spleen (splenomegaly). Felty's syndrome was first described by Augustus Roi Felty in 1924 (1895-1964).
Felty's syndrome occurs among 1-3% of those with rheumatoid arthritis (RA), especially in severe, long-term disease (reference: Sibley JT, 1991). The 50-70 age group is attacked most often and 60-70% are women. Almost everyone has clear results in "rema samples" (antibody) in the blood in the form of 4 eumatoid factors and anti-CCP/ACPA. After the introduction of effective drugs against rheumatoid arthritis, such as methotrexate and biological drugs the condition has become rarer.
Felty's syndrome is not characterized by obvious, typical symptoms, but is detected by closer examination (see below). Over time, people with Felty's syndrome are usually characterized by severe, "seropositive" Rheumatoid arthritis (RA) with visible damage to joints. Simultaneous rheumatic nodes / noduli is common (89%) and dryness in the eyes and mouth (psecondary Sjøgren's syndrome) bothers about half (reference: Sienknecht CW, 1977). Increased tendency to infection can also be a problem.
Medical history reflects longstanding Rheumatoid arthritis with joint damage and other symptoms (see above).
Clinical examination may also give rise to suspicion of enlarged spleen (splenomegaly). Swollen lymph nodes, signs of increased connective tissue in the lungs (pulmonary fibrosis), pleurisy (pleurisy), nerve inflammation (neuropathy) and blood vessel inflammation (vasculitis) in the skin can be seen in some cases Sienknecht CW, 1977).
Blood tests shows signs of rheumatic inflammation with elevated CRP and SR. Characteristic is for lby number of white blood cells (leukopenia og neutropenia: moderate (0,5-1,0) – severe below 0,5). Almost everyone is RF and CCP (ACPA) positive in blood tests. Somewhat low number of blood platelets (thrombocytopenia) and low hemoglobin (anemia) also occurs. Flow cytometry where a special examination which, if necessary, helps distinguish Felty's syndrome LGL syndrome.
Imaging. X-rays and ultrasound of joints usually show arthritis-typical injuries. Ultrasound or CT of the abdominal area (abdomen) demonstrates an enlarged spleen (>12 cm, splenomegaly).
Tissue sample from bone marrow (bone marrow biopsy) shows typical changes (myeloid hyperplasia with increased granulocytopoiesis). Histological examination and A cell-poor (hypoplastic) bone marrow is unusual and indicates that the exclusion of other conditions should be carefully considered (reference: Sienknecht CV 1977).
Similar conditions, differential diagnoses
Large spleen and/or low number of white blood cells in arthritis RA is a side effect of drugs, but also other diseases such as chronic infections, Sarcoidosis, liver damage and cancer should be considered. LGL syndrome. / LGL leukemia (neutropenia with Large Granular Lymphocytosis (LGL)/ pseudo-Felty syndrome) has similar manifestations, so that some have suggested that it is the same disease (reference: Liu X, 2011). By immunophenotyping at flow cytometry however, these conditions can be separated (reference: Patel R, 2021). Other conditions that can be considered are: amyloidosis, liver cirrhosis, LGL syndrome and drug-induced symptoms/side effects.
Antidepressants for active rheumatoid arthritis (RA) are the basic treatment that probably also counteracts the risk of developing Felty's syndrome. If Felty's syndrome is detected, it is expected DMARDs in the form of methotrexate is expected to increase the number of white blood cells with neutrophilic leukocytes after a few weeks of treatment (reference: Wassberg S, 1998) and is usually the first choice. Prednisone (for example 30-40mg/day with a tapering dose) is expected to have a faster effect, but use over time has many side effects, including the risk of infection. There are good experiences with Biological drugs, particularly rituximab, while TNF-alpha blockers have proven less effective. One tries to avoid tocilizumab (IL-6 inhibitor) and tofacitinib (JAK inhibitor) because these can trigger/exacerbate a low number of white blood cells (leukopenia) (reference: Narvaez, X). Other: Neupogen (filgrastim) can be used to increase the number of white blood cells (neutrophils) (reference: Lazaro E 2015). splenectomy (surgical removal of the spleen) was previously the standard treatment (reference: Coon WW, 1985), but is rarely done now.
In the past, the disease had a high mortality rate (25% over 5 years), but there are better life prospects with newer treatment methods (reference: Bartels CM, 2010).
- Patel R, StatPearls, 2022
- Lilleby V, 2000 (Norwegian Legeforeningen)
- Ovlia BM, 2014
- Balint GP 2004
- Grans Compendium in Rheumatology