Introduction: Skin ulcers, especially those whose location is in the lower limbs, involve a wide range of causes and appropriate clinical analysis to be performed.Case Report: We present a case report of a 64-year-old female patient diagnosed with rheumatoid arthritis mutilans, who had suffered for three years ulcerative lesions in the lower limbs.The initial approach included antibiotic management, with a subsequent histopathological diagnosis of pyoderma gangrenosum.She was treated with high doses of corticosteroids and cyclosporine, showing response in facial and knee lesions, however, the left lower limb lesion developed ischemia and subsequent necrosis, requiring suprapatellar amputation.Conclusion: The strong association between systemic diseases of the patient, as well as the differential diagnoses, the difficulty between identification and treatment, make each case of pyoderma gangrenosum a challenge for the health personnel.Underlying pathologies, characteristics of the lesions and biopsy reports should always be considered for an adequate diagnosis.