| Snapshot |
| A 5-year-old boy presents to the emergency room for abdominal pain and rash on his legs. He also reports having intermittent joint pains. A few weeks ago, he had an upper respiratory infection. On physical exam, he has nontender palpable purpura on his buttocks and lower extremities. His abdomen is mildly tender. Urine studies show proteinuria and hematuria. (Henoch-Schonlein purpura/IgA vasculitis) |
Introduction
- Clinical definition
- vasculitis caused by immune complex deposition
- Pathogenesis
- circulating antigens induce antibody formation
- the antibodies then bind to antigens, creating immune complexes
- the immune complexes then deposit in small vessels, activating complement and causing a vasculitis
- circulating antigens induce antibody formation
- General clinical features
- palpable dark-red or purple purpura
- may itch, burn, or be nontender
- may ulcerate
- Studies
- most cases are diagnosed clinically, but a biopsy may be needed
- direct immunofluorescence
- deposition of C3, IgM, IgA, and/or IgG
Cryoglobulinemic Vasculitis
- Clinical definition
- small-vessel vasculitis caused by mixed cryoglobulins affecting the skin, peripheral nervous system, and kidneys
- associated with hepatitis C virus (HCV) infection
- occurs in adults
- small-vessel vasculitis caused by mixed cryoglobulins affecting the skin, peripheral nervous system, and kidneys
- Presentation
- peripheral neuropathy
- skin involvement
- palpable purpura
- ulcerations
- livedo reticularis
- joint pain
- renal involvement
- membranoproliferative glomerulonephritis
- no gastrointestinal symptoms (in contrast to Henoch-Schonlein purpura)
- Studies
- cryoglobulins isolated from the serum
- urine studies
- proteinuria
- hematuria
- Treatment
- treat underlying HCV infection
- corticosteroids
Henoch-Schonlein purpura (IgA Vasculitis)
- linical definition
- IgA-mediated small vessel vasculitis that often follows an upper respiratory infection
- especially with group A streptococcus or parvovirus B19
- occurs in children
- IgA-mediated small vessel vasculitis that often follows an upper respiratory infection
- Presentation
- triad of
- nontender palpable purpura
- on buttocks and lower extremities
- may ulcerate
- arthralgias
- colicky abdominal pain
- nontender palpable purpura
- constitutional symptoms
- hematuria
- triad of
- Studies
- urine studies
- proteinuria
- hematuria
- direct immunofluorescence
- IgA deposition in small vessels on direct immunofluorescence
- histology
- IgA deposition in small vessels on staining
- leukocytoclasis
- urine studies
- Treatment
- typically resolves spontaneously over time
- angiotensin-converting enzyme (ACE) inhibitor
- indication
- for persistent proteinuria, which may result in end-stage renal disease or glomerulonephritis
- indication