Successful treatment of wound breakdown caused by pyoderma gangrenosum after total knee arthroplasty.

Pyoderma gangrenosum is a rare ulcerative disorder of the skin of unknown etiology. We present a case of pyoderma gangrenosum that occurred following total knee arthroplasty, which was initially misdiagnosed as severe wound infection. Repeated debridement procedures resulted in a large soft tissue defect around the anterior knee joint. The patient was treated successfully with a latissimus dorsi musculocutaneous flap under immunosuppressive therapy. Pyoderma gangrenosum is often misdiagnosed as an infected wound, but the treatment for theses differential diagnoses is completely different. When a lesion is refractory to thorough treatment for infection, a diagnosis of pyoderma gangrenosum should be considered.