Pyoderma gangrenosum is an uncommon neutrophilic dermatosis that usually presents with rapidly growing, painful, undermined, and purulent ulcers that are more likely to develop at areas of trauma. It is associated with underlying systemic diseases in more than half of cases, most commonly with inflammatory bowel disease. Pyoderma gangrenosum has no specific clinical, histologic, or laboratory findings, and so the diagnosis is based on exclusion of all other diagnostic possibilities, especially infectious causes. Misdiagnoses are frequent, with systemic vasculitides representing one of the main imitators. Treatment of pyoderma gangrenosum usually requires a multidisciplinary approach, with infliximab emerging as the best treatment option for cases associated with inflammatory bowel disease. The prognosis of pyoderma gangrenosum remains unpredictable, and recurrences are common. Here, we report a case of mucocutaneous pyoderma gangrenosum as a preceding sign of ulcerative colitis that responded to treatment with methylprednisolone and infliximab.