Pyoderma gangrenosum first presenting as a recalcitrant ulcer of the ear lobe

A 59-year-old Japanese man with pyoderma gangrenosum occurring at the unusual location of the ear lobe is herein reported. The patient was not associated with any other systemic diseases and had suffered from chilblains at the same site for ten years before the ulcer appeared. The ulcer followed the development of a purpuric exudative lesion and had neither an undermined nor a surpiginous border in the early lesion. It gradually increased in size after various conservative treatments, recurred within a month after being excised and became aggravated after the administration of potassium iodide. Repeated histopathology of the ulcer revealed a mixed inflammatory cell infiltrate with abscesses and an extravasation of red blood cells in the whole dermis, without showing leukocytoclastic vasculitis. A culture of the excised tissue yielded no growth. Laboratory tests were not specific and c-ANCA was also negative. The ulcer of the ear did dramatically respond to systemic predonisolone of 40 mg/day. The auricular and periauricular area are quite rare anatomical sites of this disease and the difference between pyoderma gangrenosum and cutaneous Wegener's granulomatosis is also discussed.