ABIM Rheumatology 1 — Questions and Answers
Question 1: Which antibody is most specific for rheumatoid arthritis?
- Antinuclear antibody (ANA)
- Anti-cyclic citrullinated peptide (anti-CCP) (Correct answer)
- Anti-double-stranded DNA (anti-dsDNA)
- Antineutrophil cytoplasmic antibody (ANCA)
Correct answer: Anti-cyclic citrullinated peptide (anti-CCP)
Anti-cyclic citrullinated peptide (anti-CCP) antibody has approximately 95% specificity for rheumatoid arthritis, making it more specific than rheumatoid factor.
Question 2: Which antibody is most specific for systemic lupus erythematosus (SLE)?
- Anti-Ro/SSA
- Anti-double-stranded DNA (anti-dsDNA)
- Anti-Smith (anti-Sm) (Correct answer)
- Anti-histone
Correct answer: Anti-Smith (anti-Sm)
Anti-Smith (anti-Sm) antibodies are the most specific antibody for SLE (~99% specific), though they have lower sensitivity than anti-dsDNA.
Question 3: A 55-year-old man presents with sudden-onset severe pain and swelling of his right great toe with a serum uric acid of 9.2 mg/dL. What is the most appropriate first-line treatment for this acute attack?
- Allopurinol
- Colchicine (Correct answer)
- Probenecid
- Febuxostat
Correct answer: Colchicine
Colchicine (along with NSAIDs or corticosteroids) is first-line for acute gout; urate-lowering agents like allopurinol should never be initiated during an acute attack.
Question 4: Which synovial fluid finding is most characteristic of gout?
- Positively birefringent rhomboid crystals
- Negatively birefringent needle-shaped crystals (Correct answer)
- WBC count >100,000/mm³ with 95% PMNs
- Turbid fluid with glucose <25 mg/dL
Correct answer: Negatively birefringent needle-shaped crystals
Gout is characterized by monosodium urate crystals that are needle-shaped and negatively birefringent under polarized light microscopy.
Question 5: A 50-year-old woman presents with dry eyes, dry mouth, anti-Ro/SSA antibodies, and anti-La/SSB antibodies. Which condition is most likely?
- Systemic lupus erythematosus
- Primary Sjögren's syndrome (Correct answer)
- Rheumatoid arthritis
- Dermatomyositis
Correct answer: Primary Sjögren's syndrome
Anti-Ro/SSA and anti-La/SSB antibodies are characteristically associated with primary Sjögren's syndrome, which presents with sicca symptoms (dry eyes and dry mouth).
Question 6: A 25-year-old man presents with low back pain and morning stiffness that improves with exercise, positive HLA-B27, and sacroiliitis on imaging. What is the most appropriate initial treatment?
- Methotrexate
- NSAIDs (Correct answer)
- Hydroxychloroquine
- Rituximab
Correct answer: NSAIDs
NSAIDs are the first-line treatment for ankylosing spondylitis (axial spondyloarthropathy); TNF inhibitors or IL-17 inhibitors are added if NSAIDs provide insufficient relief.
Question 7: Which feature of psoriatic arthritis most distinctly differentiates it from rheumatoid arthritis?
- Symmetric joint involvement
- Positive rheumatoid factor
- Dactylitis (sausage digits) (Correct answer)
- Morning stiffness lasting more than 1 hour
Correct answer: Dactylitis (sausage digits)
Dactylitis (diffuse swelling of an entire digit giving a 'sausage digit' appearance) is a hallmark of psoriatic arthritis and is not seen in rheumatoid arthritis.
ABIM Rheumatology 1
Which antibody is most specific for rheumatoid arthritis?