In peristomal PG, ulcer margins are usually described as which of the following?

• A. Scaly, crusted, non-exudative
• B. Pale and nonerythematous
• C. Smooth, circular and non-undermined margins
• D. Red to purplish, well demarcated, ragged and irregularly shaped; may be undermining

Answer: (D)

The characteristic feature of peristomal pyoderma gangrenosum ulcers is a violaceous to red-purple border that is clearly defined but often undermined and ragged, with an irregular shape. This reflects the intense inflammatory process in PG, which tends to create rapidly enlarging ulcers with edges that pull under (undermining) and have a conspicuously inflammatory, purplish border. The description of red to purplish, well demarcated yet ragged and potentially undermined margins fits this pattern precisely.

Other patterns don’t fit as well because they describe non-inflammatory or differently behaving skin changes. Scaly, crusted, non-exudative margins suggest a dermatitis-like process rather than a rapidly expanding neutrophilic ulcer. Pale and nonerythematous margins indicate little inflammatory activity, which isn’t typical of PG. A smooth, circular, non-undermined margin points toward a non-PG healing or noninflamed lesion, not the jagged, violaceous borders seen in PG.