[Postoperative pyoderma gangrenosum. Apropos of 2 cases].

The typical lesion of pyoderma gangrenosum is a rapidly extending necrotic ulceration, often associated with a system affection, inflammatory colitis, hematologic affections, rheumatic disorders. In about 30% of cases it develops on the site of a sometimes minimal injury. In the two cases reported one developed in the region of a graft after excision of a basal cell epithelioma, the other in a peritoneal drainage scar after colon resection. In patients with pyoderma gangrenosum, initial discussion must involve possible causes of the cutaneous necrosis, but in the cases reported the clinical appearance and rapid progression of the lesion, and negative results of serial bacteriologic and mycologic examinations were in favor of this diagnosis. An accurate diagnosis is essential since general corticotherapy is usually necessary.