NOTE: The term "hypersensitivity vasculitis" was not used at the conference. This was felt to represent either microscopic polyangiits or cutaneous leukocytoclastic angiitis rather than a separate entity (page 191).
Lesion: vasculitis affecting small blood vessels
|
Vessel
|
Involvement
|
|
venules
|
yes
|
|
capillaries
|
yes
|
|
arterioles
|
yes
|
|
small arteries
|
no
|
|
medium-sized arteries
|
no
|
|
large arteries
|
no
|
The only manifestation should be skin involvement.
The presence of glomerulonephritis or systemic involvement suggests another form of vasculitis. Occasionally a systemic vasculitis will first present with cutaneous involvement, with vasculitis in other organs appearing later.
Differential diagnosis:
(1) Henoch Schonlein purpura - IgA immune deposits
(2) microscopic polyangiitis - no or rare immune deposits, ANCA positive
(3) serum sickness - immune complex deposits
(4) SLE - high serum titers to ANA
(5) Wegener's granulomatosis - granulomatous inflammation, ANCA positive
(6) Churg-Strauss syndrome -eosinophilia and asthma, ANCA positive
(7) essential cryoglobulinemia - cryoglobulin deposits
