IgA Vasculitis: Clinical Presentation
IgA vasculitis presents with a classic tetrad of palpable purpura (predominantly on lower extremities), arthralgia/arthritis, abdominal pain, and glomerulonephritis with mesangial IgA deposits. 1, 2
Primary Clinical Features
Cutaneous Manifestations
- Palpable purpura is the hallmark finding, appearing as round or oval lesions predominantly on the lower legs and buttocks 1
- The purpura may also present in retiform patterns 1
- Skin lesions result from perivascular IgA deposition and neutrophilic inflammation around cutaneous vessels 1
Musculoskeletal Involvement
- Arthralgia or frank arthritis commonly occurs, typically affecting large joints 1, 2
- Joint symptoms are usually self-limited 1
Gastrointestinal Manifestations
- Abdominal pain is a dominant feature, ranging from mild discomfort to severe, intractable pain 1, 2
- Gastrointestinal bleeding may occur 1
- The severity of gastrointestinal manifestations determines short-term outcome 1, 3
Renal Involvement
- Glomerulonephritis with mesangial IgA deposits (IgA vasculitis nephritis) develops in a significant proportion of patients 1, 2
- Hematuria is a key presenting feature 2
- Renal involvement is the primary determinant of long-term prognosis 1, 3
Less Common Manifestations
While rare, the following organ systems may be affected:
- Pulmonary involvement 1, 3
- Cardiac manifestations 1, 3
- Genital symptoms 1, 3
- Neurological complications 1, 3
Age-Related Differences in Presentation
Pediatric vs. Adult Disease
- Children are affected 150-200 times more frequently than adults (incidence 1 in 1 million/year in adults) 1, 3
- Adult-onset disease follows a more severe course with higher risk of chronic renal disease and end-stage renal failure 1, 4, 5
- Up to one-third of adult patients may progress to end-stage renal failure with prolonged follow-up 3
- Renal involvement is more frequent and severe in adults compared to children 4, 3
Pathophysiology Underlying Clinical Presentation
- Immune complexes containing galactose-deficient IgA1 play a pivotal role 1
- These complexes activate neutrophils via the Fc alpha receptor (CD89), causing perivascular inflammation in skin and mesangial proliferation in kidneys 1
- The systemic nature of IgA deposition explains the multi-organ involvement pattern 1
Clinical Variants
IgA vasculitis can present in three distinct forms:
- Systemic IgA vasculitis (classic Henoch-Schönlein purpura) with multi-organ involvement 1
- Skin-limited IgA vasculitis restricted to cutaneous manifestations 1
- IgA nephropathy as a kidney-restricted variant 1, 3
Key Diagnostic Pitfall
Do not confuse IgA vasculitis with ANCA-associated vasculitis – IgA vasculitis shows immune deposits (IgA) on biopsy, while ANCA-associated vasculitides typically lack immune deposits 6. This distinction is critical for appropriate management and prognosis.