Pyoderma gangrenosum (PG) is a pathergy positive. ulcerative neutrophilic dermatosis. Pathergy phenomenon is described as a sterile pustule and an ulcer development after minor skin traumas like a bump or bruise. or needlestick injury. https://www.roneverhart.com/Paistinpannu-rst-kupari-o-28-cm-3-L/