The cause of pyoderma gangrenosum isn't well understood. It's often associated with inflammatory conditions, such as ulcerative colitis and Crohn's disease. If you have pyoderma gangrenosum, new skin trauma, such as a cut or puncture wound, may result in the formation of new ulcers. This tendency of new ulcers to form from trauma, including surgery, is known as pathergy.

Nov. 27, 2012