RESUMO
Inflammatory bowel diseases can commonly present many cutaneous lesions which can contribute to the diagnosis of the disease or its activity. The most frequent cutaneous or mucocutaneous manifestations suggesting ulcerative rectocolitis activity are erythema nodosum (3-10%), pyoderma gangrenosum (5-12%) and aphthous stomatitis (4%). Other reactive skin manifestations related to immunological mechanisms associated with the inflammatory bowel disease are: Sweet's syndrome, arthritis-dermatitis syndrome associated with inflammatory bowel disease and leukocytoclastic vasculitis. We describe the case of a young man with diagnosis of ulcerative rectocolitis, which presented an extensive cutaneous gangrene secondary to microvascular thrombosis. The case represents a dermatologic rarity and should be recognized as a cutaneous manifestation related to the hypercoagulability state observed in the disease's activity.