| Microscopic polyangiitis | Small vessel vasculitis involving skin, lung, brain, GI tract, postcapillary venules and glomerular capillaries |
- Children and adults
- Precipitated by drugs (e.g., penicillin), infections (e.g., streptococci), immune disorders (e.g., SLE)
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- Vessels at same stage of inflammation
- Palpable purpura, glomerulonephritis
- p-ANCA antibodies (>80% of cases)
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| Churg-Strauss syndrome | Small vessel vasculitis involving skin, lung, heart vessels | Children and adults |
- Allergic rhinitis, asthma
- p-ANCA antibodies (70% of cases), eosinophilia
|
| Henoch-Schönlein purpura | Small vessel vasculitis involving skin, GI tract, renal, joint vessels |
- Children and young adults
- Most common vasculitis in children
- IgA immunocomplexes
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- Palpable purpura of buttocks and lower extremities
- Polyarthritis, glomerulonephritis, GI bleeding
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| Cryoglobulinemia | Small vessel vasculitis involving skin, GI tract, renal vessels |
- Adults
- Association with HCV, type I MPGN
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- Cryoglobulins: immunoglobulins that gel at cold temperatures
- Palpable purpura, acral cyanosis of nose and ears and Raynaud’s phenomenon (reverses when in warm room)
|
| Serum sickness | Small vessel vasculitis involving immunocomplex deposition in skin vessels |
- Children and adults
- Complication of treatment with horse- or sheep-based antivenin
| Fever, urticaria with vasculitis, arthralgia, GI pain with melena |
| Infectious vasculitis | Small vessel vasculitis involving skin vessels |
- Children and adults
- Involves all microbial pathogens
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- Rocky Mountain spotted fever: tick transmission of Rickettsia rickettsiae; organisms invade endothelial cells; petechiae on palms spread to trunk
- Disseminated meningococcemia due to Neisseria meningitidis
- Capillary thrombosis produces hemorrhage into skin and confluent ecchymoses
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