• Christine Y Louie, Adam J Gomez, Richard K Sibley, Dorsey Bass, and Teri A Longacre.
• Department of Pathology, Veterans Affairs Palo Alto Health Care System, Palo Alto.
• Am. J. Surg. Pathol. 2018 Apr 1; 42 (4): 529-533.

AbstractImmunoglobulin A (IgA) vasculitis or Henoch-Schönlein purpura (HSP) typically occurs in the pediatric population, although rare cases also occur in adults. Gastrointestinal (GI) involvement is common. The "classic" histologic finding in IgA vasculitis (HSP) is leukocytoclastic vasculitis (LCV); other histologic features in biopsies of IgA vasculitis (HSP) have only been rarely described. The pathology archival files at our institution were searched for GI biopsies from patients with IgA vasculitis (HSP). Slides were retrieved and histologic and clinical features were reviewed. We identified 16 patients with IgA vasculitis (HSP) with a GI biopsy series, including both adult and pediatric patients. The most common histologic abnormality was lamina propria hemorrhage (all cases) with many cases also showing lamina propria fibrin deposition with red cell sludging and nuclear debris (7 cases). Twelve of the 16 duodenal biopsies had acute duodenitis; 3 of which were severe and erosive. Several also had an eosinophilic infiltrate. Seven of the 9 jejunal and/or ileal biopsies had acute jejunitis or ileitis. An acute colitis or proctitis was observed in 9/12 colorectal biopsies. Four biopsies contained LCV; in each of these cases, the involved vessels were small capillaries within the lamina propria. Only 1 biopsy contained deeper submucosal vessels, but they were uninvolved. Sites involved by LCV included the colorectum (2 cases), colorectum and terminal ileum, terminal ileum only, duodenum, and jejunum (1 case each). All patients presented with abdominal pain; 13/16 developed a rash, 1 following the index biopsy. Other presenting symptoms included diarrhea and/or hematochezia (8 cases), nausea/vomiting (5 cases), and intussusception (1 case). Four patients had concurrent skin biopsies showing LCV; only 1 of these patients had LCV on GI biopsy. Indications for biopsy included nonspecific presenting symptoms, absence of rash at presentation, and/or failure to respond adequately to steroid therapy. Biopsies are commonly performed in patients with or without suspected IgA vasculitis (HSP) to rule out infection, inflammatory bowel disease, and less commonly, vasculitis. In general, vasculitis is not commonly observed in GI biopsies of patients with IgA vasculitis (HSP), and the spectrum of findings includes neutrophilic infiltrate within the small bowel and colon, with the duodenum most commonly affected. While the clinical and histologic findings may mimic early inflammatory bowel disease, the presence of predominant small bowel involvement, especially erosive duodenitis, should raise suspicion for IgA vasculitis (HSP). Biopsies should be obtained before steroid therapy is initiated, if possible.

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