Acute form of pyoderma gangrenosum induced by traumatic injury

A 45-year-old man with the acute form of pyoderma gangrenosum is reported. He developed characteristic ulcers that rapidly followed violaceous erythema at sites of traumatic injury. The skin lesions repeatedly appeared six times within 7 years. Each time, the skin lesions were localized to sites of trauma, and no systemic symptoms nor abnormal laboratory findings were associated. Histological findings were acute superficial inflammation with neutrophilic infiltration into the dermis. Sweet's syndrome-like skin lesions were once associated, indicating that pyoderma gangrenosum and Sweet's syndrome have a close relationship. Nonsteroidal antiinflammatory drugs, potassium iodide, and minocycline were not effective. He was successfully treated with oral administration of corticosteroid. The pathergy of this patient must have been caused not only by the trauma itself but by additional factors such as epidermal components or contaminating micro-organisms, since traumatic injury did not always cause the skin lesions.