Internal Medicine Rheumatology and Orthopedics Questions and Answers — Questions and Answers
Question 1: A 35-year-old woman presents with a 4-month history of symmetric pain and swelling in her metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints, accompanied by morning stiffness lasting over an hour. Physical examination reveals soft, boggy swelling of the affected joints. Which of the following sets of laboratory findings would be most specific for diagnosing her condition?
- Elevated C-reactive protein (CRP) and a positive antinuclear antibody (ANA) test.
- Positive anti-cyclic citrullinated peptide (anti-CCP) antibodies and a positive rheumatoid factor (RF). (Correct answer)
- Elevated erythrocyte sedimentation rate (ESR) and hyperuricemia.
- Normal inflammatory markers and a positive human leukocyte antigen B27 (HLA-B27) test.
Correct answer: Positive anti-cyclic citrullinated peptide (anti-CCP) antibodies and a positive rheumatoid factor (RF).
The patient's presentation of symmetric inflammatory polyarthritis affecting small joints with prolonged morning stiffness is classic for rheumatoid arthritis (RA). While rheumatoid factor (RF) is commonly associated with RA, it can be present in other conditions. Anti-CCP antibodies, however, are highly specific for RA and are a key component of the diagnostic criteria. The combination of positive anti-CCP and RF provides the highest specificity for diagnosis.
Question 2: A 55-year-old male with a history of recurrent sinusitis and recent onset of shortness of breath and hemoptysis is found to have nodular opacities on chest X-ray. Urinalysis reveals red blood cell casts. Which of the following autoantibodies is most specifically associated with this patient's likely diagnosis?
- Anti-double-stranded DNA (anti-dsDNA)
- Anti-Scl-70 (anti-topoisomerase I)
- Anti-neutrophil cytoplasmic antibody, cytoplasmic pattern (c-ANCA) with anti-proteinase 3 (PR3) (Correct answer)
- Anti-neutrophil cytoplasmic antibody, perinuclear pattern (p-ANCA) with anti-myeloperoxidase (MPO)
Correct answer: Anti-neutrophil cytoplasmic antibody, cytoplasmic pattern (c-ANCA) with anti-proteinase 3 (PR3)
This patient's constellation of upper airway (sinusitis), lower airway (hemoptysis, lung nodules), and renal (glomerulonephritis with RBC casts) involvement is classic for Granulomatosis with Polyangiitis (GPA). The most specific autoantibody for GPA is c-ANCA with specificity for proteinase 3 (PR3). While p-ANCA/MPO is associated with vasculitis (like Microscopic Polyangiitis), c-ANCA/PR3 is highly characteristic of GPA.
Question 3: A 68-year-old man with stage 4 chronic kidney disease (eGFR 25 mL/min/1.73m²) presents with an exquisitely painful, swollen, and erythematous first metatarsophalangeal joint. Arthrocentesis confirms gout. Which of the following is the most appropriate initial treatment for his acute gout flare?
- High-dose oral naproxen
- Oral colchicine 1.2 mg followed by 0.6 mg in one hour
- Intra-articular glucocorticoid injection (Correct answer)
- Oral allopurinol 300 mg daily
Correct answer: Intra-articular glucocorticoid injection
In a patient with an acute gout flare and severe chronic kidney disease, both NSAIDs (like naproxen) and standard-dose colchicine are relatively contraindicated due to the risk of worsening renal function and toxicity, respectively. Allopurinol is a urate-lowering therapy and is not used for treating an acute flare; in fact, starting it during a flare can worsen symptoms. For a monoarticular flare, an intra-articular glucocorticoid injection is the safest and most effective option, providing potent local anti-inflammatory effects with minimal systemic absorption.
Question 4: A 75-year-old woman presents with a 2-month history of severe stiffness and aching in her shoulders, neck, and pelvic girdle. The stiffness is most pronounced in the morning, making it difficult for her to get out of bed. She also reports malaise and a low-grade fever. Laboratory tests show a markedly elevated ESR of 90 mm/hr. What is the most appropriate initial therapy?
- High-dose prednisone (60 mg daily)
- Low-dose prednisone (15 mg daily) (Correct answer)
- Methotrexate 15 mg weekly
- Naproxen 500 mg twice daily
Correct answer: Low-dose prednisone (15 mg daily)
The patient's age, symmetric proximal girdle pain and stiffness, morning stiffness, and markedly elevated inflammatory markers are classic for polymyalgia rheumatica (PMR). The standard and most effective first-line treatment for PMR is low-dose oral prednisone, typically in the range of 12.5-25 mg daily, which usually produces a rapid and dramatic clinical response. High-dose prednisone is reserved for suspected concurrent giant cell arteritis (GCA). Methotrexate is a steroid-sparing agent used later if needed, and NSAIDs are generally ineffective.
Question 5: A 28-year-old male presents with a 3-year history of chronic inflammatory back pain and stiffness that improves with exercise but not with rest. A plain radiograph of the pelvis is obtained. Which of the following radiographic findings in the sacroiliac joints would be most characteristic of ankylosing spondylitis?
- Juxta-articular osteopenia and marginal erosions
- Subchondral cysts and osteophyte formation
- Bilateral symmetric sclerosis and joint space fusion (ankylosis) (Correct answer)
- Punched-out erosions with sclerotic borders
Correct answer: Bilateral symmetric sclerosis and joint space fusion (ankylosis)
Ankylosing spondylitis is an inflammatory arthritis primarily affecting the axial skeleton. The hallmark radiographic finding is sacroiliitis, which characteristically presents as bilateral and symmetric erosions, subchondral sclerosis, and eventual bridging and fusion (ankylosis) of the sacroiliac joints. In advanced disease, syndesmophyte formation in the spine can lead to a 'bamboo spine' appearance.
Question 6: A 45-year-old man presents to the emergency department with the sudden onset of a severely painful, swollen, and warm right knee, making him unable to bear weight. He has a fever of 38.5°C (101.3°F). What is the most critical next step in the management of this patient?
- Obtain a serum uric acid level
- Perform an arthrocentesis of the knee (Correct answer)
- Order a plain radiograph of the knee
- Initiate empiric intravenous antibiotics
Correct answer: Perform an arthrocentesis of the knee
In a patient presenting with an acute, febrile monoarthritis, the most urgent diagnosis to exclude is septic arthritis, as it can lead to rapid joint destruction. Arthrocentesis with synovial fluid analysis (cell count, Gram stain, culture, and crystal analysis) is the single most important diagnostic test. While antibiotics will be needed if septic arthritis is confirmed, they should ideally be administered after the joint fluid is aspirated to maximize the diagnostic yield of the culture. Serum uric acid can be normal during an acute gout attack, and radiographs are often non-specific in the acute setting.
Internal Medicine Rheumatology and Orthopedics Questions and Answers
A 35-year-old woman presents with a 4-month history of symmetric pain and swelling in her metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints, accompanied by morning stiffness lasting over an hour.
Physical examination reveals soft, boggy swelling of the affected joints.
Which of the following sets of laboratory findings would be most specific for diagnosing her condition?