Pyoderma gangrenosum (PD) is a rare, chronic, relapsing, ulcerative, neutrophilic cutaneous disease and may be difficult to recognize. It is not uncommon for PD to be mistakenly diagnosed as vascular occlusive or venous disease, vasculitis, cancer, infection, exogenous tissue injury, or other inflammatory disorders. A 55-year-old woman with a 5-year history of a very painful and enlarging ulcer presented at the authors' clinic. Previously, based on an original diagnosis of venous ulcer, the wound had been surgically debrided and managed with saline-soaked gauze and compression therapy. After the authors secured a complete history (which included rheumatoid arthritis) and assessment, PD was suspected. A biopsy was performed for histological confirmation. Pyoderma gangrenosum treatment, including oral corticosteroids and topical 0.01% tacrolimus twice daily covered with nonadhesive gauze and compression wrapping, was started. After 4 weeks, the wound had improved noticeably and pain medications to manage wound pain were discontinued. The wound was completely healed after 4 months. The presence or absence of PD must be ascertained in all patients who present with a history of painful lower leg ulcers and PD risk factors, such as rheumatoid arthritis.