Background: Pyoderma gangrenosum (PG) is a rare inflammatory skin disease. Due to the similarity of the disease with other skin lesions, it is difficult to diagnose it. Herein, we report an interesting case of PG on the right leg.Case Report: A 43-year-old woman admitted to the infectious ward of Sina hospital (Hamadan, Iran) in March 2021with a painful ulcer on her right leg from 6 months before following trauma. The wound had a purulent discharge and bleeding spots. The patient also had a history of liver transplantation due to primary biliary cirrhosis ten years before, and was diagnosed with ulcerative colitis in August 2020. She had a blood transfusion every 6 months due to anemia. A skin biopsy was obtained from the patient's ulcer, and the specimen was sent for bacterial culture and histopathology. Enterococci were seen in culture, and the histopathology was in favor of PG. Treatment with parenteral vancomycin and oral prednisolone was started, and the lesion cleared almost completely after three weeks. Three months later, the patient was visited again and no recurrence was observed.Conclusion: Clinicians should consider the diagnosis of PG in necrotic ulcers following local trauma, especially in patients with associated systemic diseases, in order to start the appropriate treatment as soon as possible.