Felty syndrome is a rare complication of long-standing rheumatoid arthritis (RA) characterized by the triad of rheumatoid arthritis, splenomegaly, and neutropenia. Below is a concise overview to address your query, with a brief comparison to granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) where relevant.
Key Features of Felty Syndrome
- Clinical Triad:
- Rheumatoid Arthritis: Chronic, seropositive RA (usually with positive rheumatoid factor [RF] and anti-cyclic citrullinated peptide [anti-CCP] antibodies).
- Splenomegaly: Enlarged spleen, often detectable on physical exam or imaging.
- Neutropenia: Absolute neutrophil count <2,000/mm³, increasing risk of recurrent infections.
- Additional Features:
- Infections: Frequent bacterial infections (e.g., skin, respiratory) due to neutropenia.
- Other manifestations: Anemia, thrombocytopenia, lymphadenopathy, hepatomegaly, leg ulcers, or vasculitis (less common).
- Systemic symptoms: Fatigue, weight loss, fever.
- Epidemiology:
- Rare: Affects <1% of RA patients.
- Typically occurs in patients with long-standing RA (10–20 years duration).
- More common in women, aged 50–70 years, often Caucasian.
- Pathophysiology:
- Autoimmune destruction of neutrophils (possibly due to immune complexes or anti-neutrophil antibodies).
- Splenic sequestration of neutrophils and platelets.
- Chronic inflammation from RA contributes to bone marrow suppression.
- Diagnosis:
- Clinical criteria: RA + splenomegaly + neutropenia.
- Labs:
- Low neutrophil count (<2,000/mm³).
- High RF and anti-CCP titers.
- Anemia of chronic disease, possible thrombocytopenia.
- Elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP).
- Imaging: Ultrasound or CT to confirm splenomegaly.
- Bone marrow biopsy (rarely needed): To rule out other causes of neutropenia (e.g., malignancy).
- Exclusion: Rule out other causes of neutropenia (e.g., drugs, infections, malignancy) or splenomegaly (e.g., lymphoma, portal hypertension).
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