04/01/2026
🎇🎇🎇 MRCP Part 1 & Part 2 Pearl
Immunoglobulin A (IgA) vasculitis (IgAV; formerly Henoch-Schönlein purpura [HSP]) is the most common systemic vasculitis among children. Ninety percent of cases occur in the pediatric age group. In contrast to other forms of childhood systemic vasculitis, IgAV is usually self-limited, at least in children, and is characterized by a tetrad of clinical manifestations that vary in their presence and order of presentation:
●Palpable purpura (leukocytoclastic vasculitis) in patients with neither thrombocytopenia nor coagulopathy
●Arthralgia and/or arthritis
●Abdominal pain
●Kidney disease
IgAV occurs more often in children than in adults, but kidney involvement is more likely to occur and be more severe in older children and adults, prompting consideration of more aggressive therapy.
The classic tetrad (palpable purpura without thrombocytopenia or coagulopathy, arthritis/arthralgia, abdominal pain, and kidney disease) is virtually pathognomonic of IgAV in children. The differential diagnosis includes antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis, clotting disorders (such as the antiphospholipid syndrome), and sepsis.
IgAV in adults must be distinguished from other systemic autoimmune diseases (such as hypersensitivity vasculitis, cryoglobulinemia, ANCA-associated vasculitis, and systemic lupus erythematosus) and infection-related glomerulonephritis, which can produce similar symptoms but are treated differently. A period of follow-up may be necessary to distinguish among these conditions.
The combination of kidney disease and hemoptysis can simulate the presentation of ANCA-associated vasculitis (microscopic polyangiitis or granulomatosis with polyangiitis) or anti-glomerular basement membrane (GBM) disease.
