Healing pyoderma gangrenosum lesions on the leg of a patient who is being treated with infliximab. Pyoderma gangrenosum causes painful ulcers on the skin. It is thought to be an autoimmune disorder, where the bodys immune system attacks its own tissues. Treatment is with steroids and immunosuppressant drugs, although it can take many months for the ulcer to heal. Infliximab is an immunosuppressant anti-inflammatory drug used to treat various diseases, including pyoderma gangrenosum.