[Pyoderma gangraenosum: differential diagnosis in ulcus cruris and postoperative exacerbating processes].

A case of pyoderma gangrenosum that was initially misdiagnosed as postthrombotic ulcers is described. Surgical debridement triggered postoperative exacerbation. Dermatologic examination was then initiated and the diagnosis pyoderma gangrenosum was established. No underlying illness was detectable. Immunosuppressive therapy stopped disease activity promptly and as previously reported low-dose cyclosporine was also effective in our exceptionally therapy resistant case. Pyoderma gangrenosum should be considered as a rare, but important differential diagnosis of leg ulcers and postoperative progressive exacerbation. Timely diagnosis based on clinical suspicion is pertinent for correct therapy and to avoid iatrogenic deterioration of the disease.