Introduction: Pyoderma gangrenosum (PG) is a rare inflammatory skin disease, which is characterized by extensive ulcerative skin necrosis. The probable cause of PG is neutrophilic infiltration. In postoperative patients, the disease is often misdiagnosed as infection and the patient therefore undergoes improper treatment. Case Presentation: We report a case of PG following the external fixation of femoral and tibial fractures in a patient who underwent eight months of unsuccessful antibiotic therapy, as well as repeated wound irrigation and debridement. Conclusions: When a histopathological study was at last performed, the diagnosis of PG was confirmed and the patient was successfully treated using corticosteroids.