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This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
The Bottom Line
- IgA vasculitis presents with palpable purpura, usually on buttocks/lower extremities, plus arthralgia, abdominal pain, and renal findings
- Often follows an upper respiratory infection
- Platelet count is normal, distinguishing it from thrombocytopenic purpura
- Urinalysis and blood pressure monitoring are essential because renal involvement determines prognosis
- Severe abdominal pain can reflect GI bleeding or intussusception
Overview
Henoch-Schonlein purpura, now called IgA vasculitis, is the most common childhood vasculitis. Immune complex deposition affects small vessels in skin, joints, GI tract, and kidneys. Most cases are self-limited, but renal disease can be delayed. Management is supportive for mild disease and escalates for severe GI, renal, or other organ involvement.
Epidemiology
IgA vasculitis most often affects children aged 3-15 years. It is more common in boys and often follows respiratory infection. Recurrences occur in a subset of patients. Long-term outcome is driven mainly by nephritis severity.
Clinical Features
Symptoms
Palpable purpura without thrombocytopenia, classically lower extremities and buttocks
Arthralgia or arthritis, often knees and ankles
Colicky abdominal pain, vomiting, or GI bleeding
Hematuria, proteinuria, edema, or hypertension suggesting nephritis
Scrotal pain/swelling can occur and mimic torsion
Signs
Nonblanching palpable purpura in dependent areas
Joint swelling/tenderness without erosive arthritis
Abdominal tenderness or occult/gross blood in stool
Edema of hands, feet, scalp, or periorbital tissues
Elevated BP or edema suggesting renal disease
Investigations
First-line
CBC with plateletsPlatelet count should be normal or high; thrombocytopenia suggests ITP, leukemia, DIC, or sepsis
Urinalysis with microscopyScreen for hematuria, proteinuria, casts; repeat over time because renal disease can be delayed
Blood pressure and serum creatinineAssess renal involvement and severity
Second-line
Stool guaiac and abdominal ultrasoundIf severe abdominal pain, GI bleeding, or intussusception concern
Urine protein/creatinine ratioQuantify proteinuria if dipstick positive
Skin or renal biopsyRarely needed; shows IgA deposition when diagnosis unclear or renal disease significant
Specialist
NephrologyPersistent proteinuria, nephritic/nephrotic features, hypertension, reduced kidney function, or concerning casts
Surgery/radiologySuspected intussusception or acute abdomen
1
Supportive care
- Hydration, rest, and analgesia; acetaminophen or NSAIDs if renal function is normal and no significant GI bleeding
- Most skin and joint symptoms resolve spontaneously
- Educate family about recurrence and renal monitoring
2
Steroids and severe disease
- Corticosteroids can reduce severe abdominal or joint pain but do not reliably prevent nephritis
- Severe nephritis requires nephrology-directed therapy; options may include corticosteroids and immunosuppression depending biopsy/severity
- Treat hypertension and significant proteinuria with kidney-protective strategies when indicated
3
Monitoring
- Repeat urinalysis and BP for months after presentation to detect delayed nephritis
- Escalate for gross hematuria, persistent proteinuria, hypertension, or reduced kidney function
Complications
- IgA nephritis: Hematuria/proteinuria; rare progression to chronic kidney disease
- Intussusception: Bowel wall edema can create a lead point, often small-bowel; suspect with severe colicky pain
- GI bleeding: Can range from occult blood to significant hemorrhage
- Recurrence: Rash and abdominal/joint symptoms can recur
USMLE Step 2 CK Exam Tips
- 1Palpable purpura + abdominal pain + arthralgia + renal findings = IgA vasculitis
- 2Platelets are normal — if platelets are low, think ITP or leukemia instead
- 3Always check urinalysis and blood pressure
- 4Renal involvement determines long-term prognosis
- 5Steroids help severe abdominal/joint pain but do not reliably prevent kidney disease
- 6Intussusception is a high-yield GI complication
- 7Usually follows URI in a child
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