IgA immune complex small-vessel vasculitis in children; classic tetrad of palpable purpura, arthritis/arthralgias, colicky abdominal pain, and IgA nephropathy (renal involvement).
Most common childhood vasculitis. Boards love its classic presentation (rash on legs with joint and belly pain after a URI). Usually self-limited, but can cause serious complications like intussusception or renal failure if severe.
Typically a young child (ages 3–10) about 1–2 weeks after a URI (often strep or viral). Presents with palpable purpura on the legs (gravity-dependent areas; small vessel vasculitis, not low platelets). Often has arthritis/arthralgias (knees, ankles) and colicky abdominal pain (GI vasculitis causing crampy pain, sometimes bleeding).
Renal involvement in ~50% of cases, usually mild (microscopic hematuria). Can range to nephritic or nephrotic syndrome in severe cases (IgA deposition in glomeruli). Symptoms like hematuria or proteinuria often appear after the rash (within a few weeks).
Exam may show tender palpable purpura (purplish raised spots) mostly on lower extremities. Abdominal exam might reveal pain or GI bleeding. Joints may be swollen or tender, but without long-term damage. Children are generally well-appearing unless complications arise.
Distinguish vasculitic purpura from platelet disorders: in HSP, platelet count is normal and bleeding time/coag tests are normal (unlike ITP or DIC).
Check urine urinalysis for blood or protein in all cases to detect kidney involvement. Monitor renal function and blood pressure over time since nephritis can develop or worsen later.
Skin or renal biopsy with immunofluorescence showing IgA deposition confirms the diagnosis if needed (usually reserved for atypical cases or severe nephritis).
For significant abdominal pain, get imaging (e.g. ultrasound) to rule out intussusception (intestinal telescoping can occur in HSP).
medium-vessel vasculitis in <5y with prolonged fever, conjunctivitis, strawberry tongue (not IgA-mediated)
Meningococcemia
meningococcal sepsis with purpuric rash (fulminant, with high fever and toxicity, not an isolated vasculitis)
Mainly supportive care: ensure hydration, rest, and pain control. Avoid NSAIDs if significant renal/GI involvement (use acetaminophen for pain). Most cases resolve in ~4 weeks on their own.
Corticosteroids: used for severe symptoms such as intense abdominal pain or significant renal involvement. Steroids can reduce abdominal pain duration and help inflammation, but they don't clearly prevent kidney complications.
Severe kidney involvement (e.g., crescentic GN) may require high-dose steroids plus immunosuppressants (e.g., cyclophosphamide) and possibly plasmapheresis. Use ACE inhibitors for persistent proteinuria to protect the kidneys.
IgA = Immune complexes deposit (post-infection) in vessels → small vessel vasculitis. Also think A for After infection and for Aggregates of IgA in kidney (IgA nephropathy). HSP's purpura occur with normal platelets (key clue vs platelet disorders).
Cases often follow a strep throat or viral infection (50%+ cases); tends to cluster in winter months when respiratory infections are common.
Severe abdominal pain, vomiting, or GI bleeding in HSP → suspect complications like intussusception or bowel ischemia; requires urgent evaluation.
Child with palpable purpura → check platelet count & coags first. If platelets and coagulation are normal, think HSP (vasculitis) instead of platelet/clotting disorder.
If HSP is suspected (purpura + any of abdominal pain, arthritis, or hematuria), diagnose clinically. Consider confirmation with biopsy (skin/kidney) if atypical presentation.
Obtain baseline urinalysis (and periodic monitoring) to catch renal involvement early (hematuria, proteinuria can appear weeks later).
Supportive care for mild cases. Add corticosteroids for severe abdominal pain or significant renal involvement. Treat any underlying infection (e.g., antibiotics for strep).
Follow up over months to monitor blood pressure, urinalysis, and renal function since HSP can relapse or cause delayed kidney issues.
Young boy with a recent URI now with palpable leg purpura, arthralgia, abdominal pain, and hematuria → IgA vasculitis (HSP).
Child with known HSP who develops acute abdominal pain and "currant jelly" stools → intussusception from HSP (bowel vasculitis complication).
Case 1
A 7‑year‑old boy is brought to the clinic for rash, joint pain, and abdominal discomfort.
Case 2
A 6‑year‑old girl with IgA vasculitis develops severe abdominal pain and vomiting.
Skin biopsy immunofluorescence in IgA vasculitis (HSP) showing IgA deposits (green) in small dermal vessels.
