Immune Complex-Mediated Vessel Damage and Increased Neutrophil Migration

"Dowel-bypass syndrome has been well characterized.14 Clinical manifestations include a pustular and purpuric dermatosis, nondeforming polyarthritis, fever, and some¬ times tenosynovitis, myalgias, joint effusions, Raynaud's phenomenon, paresthesias, pericarditis, or liver disease.2,3 The pathogenesis may relate to circulating immune com¬ plexes (CICs) derived from bacterial antigens from the bowel and treatment is with oral antibiotics.1"4 Although early reports suggested that the cutaneous lesions in bowelbypass syndrome manifested as leukocytoclastic vasculitis, there is now agreement that the histopathologic features of the syndrome are the same as those in acute, febrile neutrophilic dermatosis (Sweet's syndrome).3·5 The histopathologic characteristics of leukocytoclastic vasculitis include endothelial swelling, the presence of a perivascular neutrophilic infiltrate, with breaking up of the leukocytes (leukocytoclasis) and invasion of neutrophils into blood vessel walls, fibrinoid necrosis, and extravasa¬ tion of erythrocytes. The cutaneous lesions that appear in Sweet's syndrome and bowel-bypass syndrome have all of these features except fibrinoid necrosis. Recently, we observed a syndrome with clinical and pathologic characteristics identical to those of bowel-by¬ pass syndrome in four patients who had not had bowelbypass surgery, but who did have gastrointestinal disease.6 One of the patients with colitis died of unrelated causes, but further studies of the other patients are reported herein. The development of cutaneous, pustular vasculitic lesions 24 hours after trauma to the skin (pathergy) is an important feature of Behcet's syndrome.78 Light and electron micro¬ scopic assessment of cutaneous and mucosal lesions that