meet diagnostic criteria. These criteria are based on histology, history, clinical examination and treatment. Histology: Exclusion of infection (including histologically indicated stains and tissue cultures) Pathergy (ulcer occurring at sites of trauma, with ulcer extending past area of trauma) Personal history of inflammatory bowel disease or inflammatory arthritis History of papule, pustule, or vesicle that rapidly ulcerated Clinical examination (or photographic evidence) of peripheral erythema, undermining border, and tenderness at site of ulceration Multiple ulcerations (at least 1 occurring on an anterior lower leg) Cribriform or “wrinkled paper” scars at sites of healed ulcers Decrease in ulcer size within 1 month of initiating immunosuppressive medications Treatment First-line therapy for disseminated or localized instances of pyoderma gangrenosum is systemic treatment with corticosteroids and ciclosporin. Topical application of clobetasol, mupirocin, and gentamicin alternated with tacrolimus can be effective. Pyoderma gangrenosum ulcers demonstrate pathergy, that is, a worsening in response to minor trauma or surgical debridement. Significant care should be taken with dressing changes to prevent potentially rapid wound growth. Many patients respond differently to different types of treatment, for example some benefit from a moist environment, so treatment should be carefully evaluated at each stage. Papules that begin as small "spouts" can be treated with Dakin's solution to prevent infection and wound clusters also benefit from this disinfectant. Wet to dry applications of Dakins can defeat spread of interior infection. Heavy drainage can be offset with Coban dressings. Grafting is not recommended due to tissue necrosis. If ineffective, alternative therapeutic procedures include systemic treatment with corticosteroids and mycophenolate mofetil; mycophenolate mofetil and ciclosporin; tacrolimus; thalidomide; infliximab; or plasmapheresis. See also Superficial granulomatous pyoderma Brown recluse spider bite References External links Reactive neutrophilic cutaneous conditions Rare diseases Gangrene Necrosis