New look at pyoderma gangrenosum.

Pyoderma gangrenosum cannot be viewed simply as "an ulcer with undermined bluish borders," since this description recognizes only one stage of the evolving process. Patients with this disorder often have cutaneous lesions including papules, pustules, and plaques that evolve and resolve without ever passing through an ulcerative stage. Moreover, such patients frequently have a variety of internal inflammatory and ulcerative disorders. The nature of these disorders as well as the increasing evidence of grossly altered immunity in pyoderma gangrenosum is also presented.