IgA vasculitis (IgAV), formerly known as Henoch-Schonlein purpura (HSP), is an acute immune complex-mediated small vessel vasculitis that most commonly occurs in children. It is often preceded by an upper respiratory tract infection and typically presents with a tetrad of symptoms: palpable purpura, arthritis/arthralgia, abdominal pain, and renal disease. However, in any individual patient, only some of the classic tetrad of symptoms may be present. IgAV is a clinical diagnosis, but in particularly unclear or atypical cases a biopsy may be used to confirm the diagnosis. Because the disease course is usually self-limiting, treatment is generally supportive. Severe cases may require glucocorticoids, antihypertensive drugs, and possibly dialysis. IgAV has an excellent prognosis, usually resolving within one month when not complicated by significant renal disease.
Epidemiological data refers to the US, unless otherwise specified.
The exact pathogenesis is unknown and assumed to be multifactorial. Factors that likely play a role include:
- Preceding infection
- IgA nephropathy
- Genetic predisposition
- Drugs (e.g., some antibiotics and antiarrhythmics) and vaccines (e.g., yellow fever, cholera)
- Symptom onset often 1–3 weeks after an infection, typically affecting the upper respiratory tract 
- Skin: (∼ 100% of cases)
- Joints: (∼ 75% of cases) arthritis/arthralgia, most common in the ankles and knees
- Gastrointestinal tract (∼ 60% of cases)
- Kidneys: (∼ 50% of cases): IgAV nephritis with signs and symptoms of
- Scrotum (scrotal swelling, pain, and tenderness)
- Central and peripheral nervous system (e.g., headaches, seizures, focal neurologic deficits, ataxia, intracerebral hemorrhage, central and peripheral neuropathy)
- Respiratory tract (e.g., mild interstitial changes, pulmonary hemorrhage)
- In rare cases: eyes (e.g., keratitis, uveitis)
IgAV is characterized by a tetrad of clinical features: palpable purpura, arthritis/arthralgia, GI symptoms, and renal disease. IgAV is one of the important differential diagnoses to consider in cases of pediatric limp.
IgAV is characterized by PAPAH: purpura, abdominal pain, arthritis/arthralgia, and hematuria.
IgAV is one of the important differential diagnoses to consider in pediatric limp.
IgAV is a clinical diagnosis; , laboratory tests are not essential to IgAV diagnosis. However, they may be useful for excluding differential diagnoses in patients exhibiting only one or two of the IgAV tetrad of symptoms, as is often the case in the first few days. Laboratory tests are also useful for monitoring the extent of renal involvement, which helps determine the prognosis. Definitive diagnosis in uncertain cases is made via biopsy. 
- Indications: useful in patients with an incomplete or unusual presentation
- Complete blood cell count with differential
- Coagulation profile: usually normal
- Serum antibodies and complement
- Serum chemistry
- Urinalysis to assess possible renal disease
- Inflammatory markers
- In case of GI involvement: positive stool guaiac
- Indication: performed in patients with marked abdominal symptoms or suspected complications
- Modalities: abdominal ultrasound/CT
- Indications: reserved for patients with unusual skin presentations or severe renal involvement (e.g., persistent nephritic syndrome)
- Skin: leukocytoclastic vasculitis with IgA and C3 immune complex deposition (hallmark) in small vessels of the superficial dermis
|Clinical feature of IgAV||Differential diagnosis||Distinguishing feature|
|Renal disease|| |
The differential diagnoses listed here are not exhaustive.
Most cases of IgAV are self-limiting and only require supportive care (e.g., pain management) with regular outpatient follow-up; . Severe IgAV requires hospitalization and intensive medical therapy.
- Outpatient treatment
- Usually no treatment necessary
- NSAIDs for pain management, rest, and adequate hydration
- Discontinuation of suspected precipitating drug, if applicable
Severe disease 
- Inpatient treatment
- Systemic glucocorticoids for severe abdominal pain not relieved by NSAIDs
- IV fluids to maintain hydration
- In case of severe renal disease
- Renal 
We list the most important complications. The selection is not exhaustive.
- Blood pressure monitoring and urinalysis
- Symptomatic patients: weekly or biweekly testing
- After symptoms subside: monthly testing for the first 6 months, then every other month for an additional 6 months
- Symptom-free for > 12 months: perform tests at subsequent well-child visits
- In patients with abnormal blood pressure or urinalysis