Lead
A few days after a cold, purple dots spread across the child's ankles and knees. The child complained of pain and refused to walk. Most parents who encounter this have no idea at first what they are looking at.
This is a typical presentation of IgA vasculitis (formerly called Henoch-Schönlein purpura, or HSP) — a form of vasculitis specific to childhood. The majority of cases resolve on their own, but a kidney complication — IgA nephritis (purpura nephritis) — is the most important long-term concern.
What IgA Vasculitis Is
IgA vasculitis is a systemic vasculitis: inflammation of blood vessel walls, leading to vessel damage and reduced blood flow to affected tissues of small blood vessels, triggered by immune complex: a cluster of antigens bound to antibodies that can deposit in vessel walls and trigger local inflammation deposition (primarily IgA: immunoglobulin A, an antibody class that protects mucosal surfaces; abnormal IgA deposits trigger vessel inflammation in this disease) in vessel walls. It is the most common vasculitis in children, with peak onset between ages 2 and 11. Reported prevalence is 13–20 cases per 100,000 children per year [6].
The four cardinal features:
- Purpura: small hemorrhages into the skin producing red or purple spots that do not blanch when pressed; caused here by vessel wall inflammation, not low platelets: palpable, non-thrombocytopenic: not caused by low platelet count; the purpura results from vessel wall damage rather than a clotting deficiency purpura favoring the lower limbs and buttocks. Platelet count is normal.
- Joint pain or arthritis: primarily affecting the knees and ankles; walking may become too painful.
- Abdominal pain: due to vasculitis of the gut wall; intussusception has been reported as a complication.
- Nephritis (purpura nephritis): manifests as hematuria: presence of blood in the urine, visible as pink or red color or detectable only on urinalysis and proteinuria: abnormal leakage of protein into the urine, indicating kidney filter damage.
The 2010 EULAR/PRINTO/PRES diagnostic criteria require palpable purpura (mandatory) plus at least one of the above features [2].
Natural Course and Recurrence
The majority of IgA vasculitis episodes resolve within four to six weeks. Some children require hospitalization — for severe abdominal pain or progressive nephritis — but the mainstay of management is rest and symptomatic treatment.
Recurrence occurs in approximately 30–40% of cases. Recurrent episodes are usually milder than the first and resolve spontaneously. Even so, recording symptoms and seeking medical review during recurrence remains important.
Corticosteroids are used when severe abdominal pain or progressive nephritis is present, but are not recommended for mild disease. NSAIDs (ibuprofen and similar agents) are used to relieve joint pain, though their use requires caution in the context of renal involvement — follow physician guidance.
Purpura Nephritis — The Most Important Long-Term Complication
In IgA vasculitis, the long-term issue that matters most is kidney involvement. Reported rates of nephritis range from 30–50% [3,4], appearing as hematuria and proteinuria.
Most cases of purpura nephritis resolve without intervention, but a small proportion progress to chronic kidney disease. In long-term follow-up studies extending beyond 30 years, the proportion progressing to end-stage renal failure is approximately 2–5% [4]. Early detection and specialist involvement allow for preventive interventions in some cases.
For this reason, regular urinalysis is recommended for one to three months after diagnosis of IgA vasculitis. Monitoring whether blood or protein appears in the urine is the single most concrete action that protects long-term kidney outcomes.
Home Monitoring
The following signs are reasons to return to a clinician:
- Red or pink urine: possible macroscopic hematuria — seek evaluation promptly
- Foamy urine: can indicate heavy proteinuria
- Swelling of the face or hands: possible protein loss from the kidneys (nephrotic syndrome)
- Severe abdominal pain or repeated vomiting: raises the possibility of intussusception
- Purpura spreading to the trunk or face: rare, but may signal more severe disease
Keeping a dated record of symptom progression — the extent of purpura, severity of abdominal pain, joint mobility — is useful when the child is seen again. "More than last week, or less" is a trend that only a parent's continuous observation can capture.
Summary
The acute phase of IgA vasculitis typically resolves on its own. What matters for long-term management is surveillance for kidney involvement. Regular urinalysis in the months following diagnosis, combined with home monitoring, is the practical foundation for protecting prognosis. The visual signal — purpura on the lower limbs — tends to prompt early presentation, but it is the follow-up that defines how well this condition is managed.
References
- Tizard EJ, Hamilton-Ayres MJ. Henoch Schonlein purpura. Arch Dis Child Educ Pract Ed. 2008;93(1):1–8. doi:10.1136/adc.2005.083550. PMID: 18208968.
- Ozen S, Pistorio A, Iusan SM, et al. EULAR/PRINTO/PRES criteria for Henoch-Schönlein purpura, childhood polyarteritis nodosa, childhood Wegener granulomatosis and childhood Takayasu arteritis. Ann Rheum Dis. 2010;69(5):798–806. doi:10.1136/ard.2009.116095. PMID: 20418544.
- Mir S, Yavascan O, Mutlubas F, Yeniay B, Sonmez F. Clinical outcome in children with Henoch–Schönlein nephritis. Pediatr Nephrol. 2007;22(1):64–70. doi:10.1007/s00467-006-0244-x. PMID: 17028874.
- Davin JC, Coppo R. Henoch-Schönlein purpura nephritis in children. Nat Rev Nephrol. 2014;10(10):563–573. doi:10.1038/nrneph.2014.126. PMID: 25113611.
- Japan Pediatric Society. Clinical Practice Guidelines for Henoch-Schönlein Purpura. 2013.
- Saulsbury FT. Henoch-Schönlein purpura. Curr Opin Rheumatol. 2001;13(1):35–40. doi:10.1097/00002281-200101000-00007. PMID: 11148714.