A 19-year-old man presented with persistent epigastric and left lower quadrant pain. Suspected infectious enteritis was treated conservatively without improvement. Upper gastrointestinal endoscopy on day 7 demonstrated multiple erosions and ulcers in the descending duodenum. Initial biopsy showed only nonspecific inflammation. Serologic testing revealed markedly decreased Factor XIII activity, suggesting vasculitic consumption. On day 12, mild transient purpura appeared on both feet. Retrospective immunohistochemical staining of the duodenal specimens revealed IgA deposition in vascular walls and necrotizing small-vessel vasculitis, confirming IgA vasculitis. Oral prednisolone (40 mg/day) induced rapid remission.
IgA vasculitis should be considered in patients with abdominal pain, duodenal lesions, or reduced Factor XIII activity even in the absence of early cutaneous findings.
