Inflammatory Bowel Disease USMLE Step 1 Practice Question
A 35-year-old man with a 10-year history of Crohn disease presents to the clinic with a 2-week exacerbation of diarrhea (6-8 loose stools daily), fever (38.2°C), and new-onset pain in both knees and ankles. On examination, he has tender, erythematous nodules on his anterior shins. Laboratory studies show hemoglobin 12.8 g/dL, CRP 8.2 mg/dL, and ESR 42 mm/hr. His current medications include mesalamine but he has not been on immunosuppressive therapy. Which of the following best explains the relationship between his extraintestinal manifestations and his underlying disease?
Answer choices
- AErythema nodosum and arthralgia are independent extraintestinal manifestations that develop randomly and will persist despite control of bowel inflammation
- BThe arthralgia represents enteropathic arthritis, which is HLA-B27 associated and occurs exclusively in ulcerative colitis, not Crohn disease
- CThese manifestations are extraintestinal complications that require biological therapy (anti-TNF agents) regardless of the degree of intestinal inflammation control
- DErythema nodosum is pathognomonic for Crohn disease and is caused by direct invasion of Mycobacterium avium subspecies into dermal tissues
- EThese are disease-associated extraintestinal manifestations that correlate with active intestinal inflammation and typically improve with control of bowel diseaseCorrect answer
- FThe combination of erythema nodosum and arthralgia indicates systemic vasculitis that requires corticosteroids independent of mesalamine therapy
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