Urticarial plaques that last longer than 24 hours and burn or sting more than
they itch characterize urticarial vasculitis. Histologically, urticarial
vasculitis sits in a continuum lying between chronic urticaria and conventional
cutaneous leukocytoclastic vasculitis. The infiltrates tend to be sparser than
conventional LCV, but neutrophil dominant compared to chronic urticaria. The
presence of slight nuclear debris and/or scattered
extravasated red blood cells is a histologic clue to urticarial vasculitis.
Direct immunofluorescence examination reveals vascular deposition of
immunoreactants, mostly C3 or IgM,in .50% of all patients.Am
J Dermatopathol Volume
28, Number 6, December 2006