What is causing this woman’s recurring abdominal pain?

A 19-year-old female exchange student presents to the emergency department with severe abdominal pain and a swollen right knee. She has had recurrent episodes of abdominal pain for the past 5 years which last 2-3 days before resolving spontaneously. Previous investigations have all failed to identify a cause. She mentions that several family members back home in Turkey have similar symptoms. On examination, she has a temperature of 39.4°C and a heart rate of 125. Her abdomen is diffusely tender with rebound tenderness. A right knee effusion is present, and a raised, tender erythematous lesion on her left lower leg is noted. Laboratory testing reveals an elevated white cell count with a neutrophilic predominance, as well as elevated ESR, CRP, and SAA protein.

A favorable response to which medication supports this patient’s most likely diagnosis?

A. Anakinra
B. Prednisone
C. Azathioprine
D. Colchicine

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