Rheumatology · Autoimmune Arthritis
The facts most likely to be tested
Rheumatoid arthritis presents with symmetric polyarthritis involving the proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joints with morning stiffness lasting longer than one hour.
The distal interphalangeal (DIP) joints are characteristically spared in rheumatoid arthritis, which helps distinguish it from osteoarthritis.
Anti-cyclic citrullinated peptide (anti-CCP) antibodies are the most specific serologic marker for rheumatoid arthritis.
Rheumatoid factor (RF) is a sensitive but non-specific marker that forms immune complexes contributing to systemic inflammation.
Atlantoaxial subluxation is a life-threatening complication of cervical spine involvement that requires screening before intubation.
Methotrexate is the first-line disease-modifying antirheumatic drug (DMARD) for the management of rheumatoid arthritis.
Felty syndrome is the classic triad of rheumatoid arthritis, splenomegaly, and neutropenia.
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A 45-year-old woman presents with a 4-month history of pain and swelling in her hands. She reports morning stiffness that lasts for approximately 90 minutes before improving. Physical examination reveals bilateral swelling of the MCP and PIP joints with ulnar deviation of the fingers. The DIP joints are spared. Laboratory studies show an elevated erythrocyte sedimentation rate and positive anti-CCP antibodies.
What is the most appropriate initial pharmacologic therapy to prevent joint destruction?
Methotrexate
The patient's presentation of symmetric inflammatory arthritis involving MCP/PIP joints with morning stiffness is classic for rheumatoid arthritis, and methotrexate is the gold-standard first-line DMARD.
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Etiology / Epidemiology
Autoimmune inflammatory disease affecting women 30-50 years old. Strong association with HLA-DR4.
Clinical Manifestations
Symmetric polyarthritis of MCP and PIP joints with morning stiffness >60 minutes.
Diagnosis
Anti-cyclic citrullinated peptide (anti-CCP) is the most specific test; Rheumatoid Factor is sensitive.
Treatment
Methotrexate is the first-line DMARD; teratogenic and requires folate supplementation.
Prognosis
Progressive joint destruction leads to permanent deformity; increased risk of cardiovascular disease.
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Epidemiology & Etiology
RA is a chronic systemic autoimmune disease with a 3:1 female-to-male ratio. Genetic predisposition is linked to the HLA-DR4 allele. Smoking is a major environmental trigger that promotes citrullination of proteins.
Pertinent Anatomy
The disease primarily targets the synovium of diarthrodial joints. It characteristically spares the DIP joints, distinguishing it from osteoarthritis. Cervical spine involvement can lead to atlantoaxial subluxation.
Pathophysiology
T-cell mediated immune response leads to synovial hyperplasia, forming a pannus. This invasive tissue secretes TNF-alpha and IL-1, causing cartilage and bone erosion. Chronic inflammation results in systemic manifestations including vasculitis and anemia of chronic disease.
Clinical Manifestations
Patients present with symmetric swelling of the MCP, PIP, and wrist joints. Classic deformities include boutonniere and swan-neck deformities. Cervical spine instability is a critical red flag requiring caution during intubation. Extra-articular findings include rheumatoid nodules and Sjogren's syndrome.
Diagnosis
The ACR/EULAR criteria are used for classification. Anti-CCP antibodies are the most specific diagnostic marker. Rheumatoid Factor is positive in 70-80% of patients. Radiographs show marginal erosions and periarticular osteopenia.
Treatment
Methotrexate is the gold-standard initial DMARD. Hepatotoxicity and bone marrow suppression require regular monitoring. If inadequate, add biologic DMARDs like TNF-inhibitors. Screen for latent TB before starting biologics.
Prognosis
Early initiation of DMARDs is essential to prevent joint destruction. Patients have a significantly higher mortality rate due to accelerated atherosclerosis. Monitor for Felty syndrome (RA, splenomegaly, neutropenia).
Differential Diagnosis
Osteoarthritis: spares MCP joints, no morning stiffness
Systemic Lupus Erythematosus: non-erosive arthritis, positive ANA
Psoriatic Arthritis: involves DIP joints, dactylitis
Gout: monoarticular, needle-shaped negatively birefringent crystals
Reactive Arthritis: follows infection, asymmetric lower extremity involvement