Pyoderma gangrenosum is a rare inflammatory reactive dermatosis marked by painful cutaneous ulcers. Diagnosis of pyoderma gangrenosum is usually made based on past medical history and after the exclusion of other possible diseases based on the clinical manifestations of the lesion. Diseases that show rapid progression to necrosis and that should not be misdiagnosed as pyoderma gangrenosum include malignant neoplasms and necrotizing fasciitis. Immunosuppressive agents such as steroids and cyclosporine are considered first-line therapy. Surgical removal of the necrotic tissues is contraindicated, as it may further induce immune reaction and promote ulcer to enlarge. Here, we present a case to encourage plastic surgeons to consider pyodermagangrenosum in the differential diagnosis of idiopathic ulcers. Satisfactory outcomes for patients with pyodermagangrenosum may be expected when using steroids and immunosuppressive agents during the early stage of the disease.