Henoch-Schönlein purpura (HSP), more recently termed immunoglobulin A (IgA) vasculitis, is a systemic small-vessel vasculitis characterized by perivascular IgA deposition. This disease manifests clinically as palpable purpura, arthralgia, gastrointestinal symptoms, and renal dysfunction. Although ileitis can be seen in HSP, terminal ileitis is virtually pathognomonic for Crohn disease. We present a comprehensive review of the literature on this association, including 2 cases of our own, to demonstrate the importance of considering HSP in the differential diagnosis of ileitis suggestive of Crohn disease. We review the growing body of literature suggesting a pathophysiologic link between the conditions, possibly through an IgA-mediated mechanism.
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