Main decision tree
Vasculitis in children: IgA vasculitis
Key points
- IgA vasculitis: palpable purpura on the legs and buttocks with normal platelets, plus arthritis, colicky abdominal pain or hematuria.
- Vasculitic purpura is palpable; thrombocytopenic petechiae are flat.
- Initial tests: blood pressure, urinalysis, CBC, coagulation profile and metabolic panel.
- Steroids may shorten severe abdominal or joint pain but do not prevent nephritis.
- Intussusception in IgA vasculitis is usually ileoileal: diagnose by ultrasound.
- Check blood pressure and urinalysis for at least 6 months (often 12), even if the first urine was normal; high BP or proteinuria → nephrology.
- Behçet: recurrent oral and genital ulcers, uveitis and a positive pathergy test; GPA: sinus disease, lung nodules and glomerulonephritis with PR3-ANCA.
Recognize and evaluate IgA vasculitis
IgA vasculitis often follows an upper respiratory infection, mostly in school-age children. Purpura is required for the diagnosis. The rash may follow the joint or abdominal pain by days, which confuses the early picture.
- Palpable purpura on the legs and buttocks, with a normal platelet count.
- Arthritis or arthralgia, often of the ankles and knees.
- Colicky abdominal pain, sometimes with GI bleeding.
- Kidney involvement: hematuria, proteinuria or high blood pressure.
- Tests: blood pressure, urinalysis, CBC, coagulation profile and metabolic panel (kidney function, albumin).
- Painful scrotal swelling in a boy: Doppler ultrasound to exclude testicular torsion.
- Anemia: GI blood loss, or low erythropoietin from kidney disease.
Treating IgA vasculitis
- Most children need supportive care only: fluids, rest and pain relief.
- NSAIDs for joint pain when kidney function and urinalysis are normal.
- Glucocorticoids for severe abdominal pain, orchitis or other severe organ involvement; they shorten symptoms.
- Glucocorticoids do not prevent later nephritis, so they are not given for that reason.
Abdominal complication: intussusception
Bowel wall swelling and bleeding can lead the bowel to telescope. Suspect it with worsening colicky pain, vomiting or currant-jelly stool.
- Usually ileoileal, not the ileocolic type of idiopathic intussusception.
- Diagnose with ultrasound.
- Ileoileal intussusception often cannot be reduced by enema and may need surgery.
Kidney follow-up
Nephritis is the main cause of long-term morbidity, including chronic kidney disease. It can appear weeks to months after the rash, so a normal first urinalysis is not enough.
- Repeat blood pressure and urinalysis for at least 6 months, often 12, after onset.
- High blood pressure or proteinuria: refer to nephrology.
- Significant proteinuria or reduced kidney function may need a kidney biopsy and immunosuppression.
Behçet disease
- Recurrent oral ulcers plus genital ulcers, uveitis or skin lesions such as erythema nodosum and pseudofolliculitis.
- Pathergy test: a sterile needle prick turns into a pustule within 24–48 hours.
- Serious complications: uveitis with vision loss, CNS disease, venous thrombosis and arterial aneurysms.
- Mouth and genital ulcers: colchicine (topical steroids for oral ulcers).
- Eye disease: urgent ophthalmology; azathioprine or an anti-TNF agent (EULAR 2018).
Granulomatosis with polyangiitis
- Chronic destructive sinus and nasal disease (crusting, nosebleeds, saddle nose); subglottic stenosis is more common in children.
- Lung nodules, cavities or pulmonary hemorrhage.
- Rapidly progressive glomerulonephritis.
- Antibody: PR3-ANCA (c-ANCA).
- Induction: glucocorticoids plus rituximab (or cyclophosphamide), then maintenance therapy; involve nephrology (ACR/VF 2021).
Common questions
How long should urine be checked after IgA vasculitis (HSP)?
Check blood pressure and urinalysis for at least 6 months, and often for 12 months, because nephritis can start after the rash has gone.
Do steroids prevent kidney disease in IgA vasculitis?
No. Steroids can ease severe abdominal or joint pain, but they do not prevent later nephritis.
What type of intussusception happens in IgA vasculitis?
Usually ileoileal, rather than the ileocolic type seen in idiopathic intussusception. It is diagnosed by ultrasound and may need surgery.
Study this topic
Sources
- SHARE European consensus recommendations for the diagnosis and treatment of IgA vasculitis (Rheumatology 2019)
- 2018 update of the EULAR recommendations for the management of Behçet's syndrome (Ann Rheum Dis)
- 2021 ACR/Vasculitis Foundation guideline for ANCA-associated vasculitis (Arthritis Rheumatol)
Written for Pedemy in our own words from the sources above; checked November 2026. For education only, not medical advice; check doses and local protocols before treating a patient. Pedemy is independent and not affiliated with or endorsed by the organizations cited.