Malignant pyodermas revisited.

The concept of malignant pyoderma (MP) has created controversy since its origin. The distinction of this disease from pyoderma gangrenosum was based on clinical criteria and response to treatment. Herein we discuss our current ideas on this entity and its possible relationship to Wegener's granulomatosis (WG). Follow-up data from the three original cases of MP are reported, as well as additional clinical and laboratory data from cases subsequently thought to represent MP. Many of these cases have similar clinical features such as facial and periauricular ulceration and occasionally signs or symptoms of WG, including positive titers of antineutrophil cytoplasmic antibodies (with a diffuse cytoplasmic staining pattern) (cANCA). MP represents a distinctive clinical disorder and may be a dermal manifestation of WG. Some cases of MP may represent pyoderma gangrenosum or other undefined systemic illnesses. Such cases of WG can be distinguished on the basis of clinical, histopathologic, and laboratory evidence including cANCA titers. MP should no longer be used as a final clinical diagnosis.