OVERVIEW
Felty syndrome is a severe form of rheumatoid arthritis characterized by splenomegaly and decreased white blood cell counts in addition to the typical clinical features of rheumatoid arthritis. The cause of the decreased white blood cell count is related to hypersplenism, or the presence of specific antibodies against neutrophils, or the presence of myelosuppressive factors. These patients usually have high titers of rheumatoid factor and antinuclear antibodies, subcutaneous nodules and rheumatoid arthritis.
Etiology
The etiology is unknown.
Symptoms
Splenomegaly and granulocytopenia may precede rheumatoid arthritis symptoms in a few cases of patients with this disease. The arthropathy is often more severe than in rheumatoid arthritis, with bone invasion and deformity, but there are also mild cases. About 1/3 of cases have inactive synovitis, and the spleen may vary in size from just palpable to massive.1/3 of patients may have neutropenia and the typical Felty’s syndrome features of rheumatoid arthritis, but no splenomegaly.
About 60% of patients with this disease have secondary infections. The site of infection is most commonly the skin and respiratory tract. The causative organisms are mostly common staphylococci, streptococci, and gram-negative bacilli. Infections may be associated with granulocytopenia.
Felty’s syndrome may be associated with hepatic nodular regenerative proliferation, a characteristic liver lesion rarely seen in lupus erythematosus and other connective tissue diseases. Histologic hepatic involvement is seen in 60% of Felty patients and may be associated with abnormal liver function, while some patients present with histologic abnormalities but normal liver function.
Joint manifestations are not significantly different from typical rheumatoid arthritis. Typical symptoms often appear months to years after the onset of joint symptoms, and thus patients tend to be over 40 to 50 years of age. Skin hyperpigmentation in exposed areas, skin-mucosal-calf ulcers, purple spots, dry syndrome, pericarditis, pleurisy, peripheral neuropathy, mild hepatomegaly, enlarged lymph nodes, and weight loss may also occur.
Examination
1. Laboratory examination
There are changes in all cell lines of the blood system. In addition to mild anemia due to decreased serum iron binding capacity, which is common in rheumatoid arthritis, shortening of the life span of red blood cells is also a feature. Platelets are mildly decreased. Granulocytopenia is extremely prominent and can be as low as 0.1×109/L in severe cases.
2. Other auxiliary tests
(1) Bone marrow image shows granulocyte maturation disorders.
(2) Immunologic examination Rheumatoid factor and antinuclear antibody are often positive.
Diagnosis
Rheumatoid arthritis, splenomegaly and granulocytopenia are the three main signs, and the diagnosis can be confirmed by combining them with other immunologic tests, but the diagnosis should be further established by combining the clinical manifestations, medical history and physical examination.
Treatment
1. Hormones
Hormones are usually the drug of choice, but the efficacy is only transient, and complete remission is rare. Recently, it has been reported that hormone shock therapy can be effective.
2. Splenectomy
Splenectomy is recommended for patients who have failed hormonal therapy and have a granulocyte count below 1.0×109/L, severe anemia (hemolytic) or thrombocytopenia, and recurrent infections. 80% of the patients can obtain hematological improvement after surgery, and recurrent infections and calf ulcers are also mostly improved.
3. Other therapies
Including anti-rheumatic agents, penicillamine, gold preparations can be tried. However, due to the low granulocytes, the use of immunosuppressive drugs should be cautious. Recently, it was reported that the combined use of hormone and tretinoin can alleviate the condition.
4. Symptomatic treatment
Use antibiotics with the smallest possible antigenicity to control the infection, because many antibiotics can aggravate the already existing immune response in the body, so antibiotics should be carefully selected for the treatment of infections in this disease.
Prognosis
The disease is often more severe than normal rheumatoid arthritis, with bone invasion and deformity. About 60% of patients have secondary infections, most often in the skin and respiratory tract, and abnormal liver function. Most patients have mild to moderate anemia and have a poor prognosis.