Histologic specimens from 41 rabbits were studied for changes resulting fro
m the manual injection of brown recluse spider venom. Major findings includ
ed a mixed inflammatory cell infiltrate, coagulative tissue necrosis, and v
asculitis. All specimens demonstrated a well-delineated zone of eosinophili
c staining recognizable as "mummified" coagulative necrosis of the epidermi
s and dermis. A dense band of neutrophils bordered the zone of necrosis. Im
mediately adjacent to the neutrophilic band, small vessel vasculitis was a
universal finding. Degranulated eosinophils and neutrophils and macrophages
filled with eosinophilic granules were common. Inflammatory foci were ofte
n centered on groups of lipocytes within the dermis. Large vessel vasculiti
s resembling that seen in polyarteritis nodosa was present deep to 7 of the
40 eschars. Large vessel vasculitis may contribute to the large zones of n
ecrosis seen after some brown recluse spider bites. Eosinophils may play a
role in tissue damage after envenomation.