IgA vasculitis (formerly known as Henoch-Schonlein purpura (HSP)) is a type of non-thrombocytopenic immune-mediated small vessel acute leukocytoclastic vasculitis.
It tends to occur in the pediatric population (peak incidence 3-10 years) 3.
In order to differentiate from other types of vasculitides, the four commonly adopted diagnostic criteria by the American College of Rheumatology are:
- age of onset less than 20 years (although some case series show disease involvement in older individuals)
- palpable skin purpura
- gastrointestinal bleeding
- intussusception, typically ileoileal
- biopsy showing granulocytes around small arteriolar/venular walls
There is the deposition of IgA immune complexes in small vessels.
Commonest organ systems which get involved are:
- skin: 95-100%, usually the first organ to get involved
- gastrointestinal tract: 50-75%
- joints: ~80% 6
- central nervous system 5,7
May show evidence of bowel wall thickening due to hemorrhage and/or evidence of bowel obstruction. Plain film features are however non-specific.
Small bowel follow-through may show evidence of separation of bowel loops, "thumbprinting" and/or mucosal thickening.
May show multifocal bowel thickening, lymphadenopathy, mesenteric edema and vascular engorgement. Although non-specific, CT findings may aid in the diagnosis of IgA vasculitis in a young patient with acute gastrointestinal illness along with other, e.g. cutaneous features of IgA vasculitis. Intussusception, typically ileoileal type, is also seen.
Echogenic kidneys, target or doughnut sign in case of intussusception. IgA vasculitis has also been shown to cause massive scrotal edema and can be a source of severe pain in young boys 9.
The disease is self-limiting in most instances.
- small bowel intussusception
- small bowel obstruction
- small bowel infarction: 3-5% 3
- bowel perforation
History and etymology
It is named after Eduard Heinrich Henoch, German pediatrician (1820-1910) 8 and Johann Lukas Schönlein, German physician (1793-1864).
On a CT/contrast study for the bowel consider:
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- 7. Bartynski WS. Posterior reversible encephalopathy syndrome, part 1: fundamental imaging and clinical features. AJNR Am J Neuroradiol. 2008;29 (6): 1036-42. doi:10.3174/ajnr.A0928 - Pubmed citation
- 8. E. Henoch: Über den Zusammenhang von Purpura und Intestinalstörungen. Berliner Klinische Wochenschrift, 1868; 5: 517-519.
- 9. Ben-Sira L, Laor T. Severe scrotal pain in boys with Henoch-Schönlein purpura: incidence and sonography. Pediatr Radiol. 2000;30 (2): 125-8. Pubmed citation.