Pyoderma gangrenosum usually starts with a small, red bump on your skin, which may resemble a spider bite. Within days, this bump can develop into a large, painful open sore. The ulcer usually appears on your legs, but may develop anywhere on your body. Sometimes it appears around surgical sites. If you have several ulcers, they may grow and merge into one larger ulcer.
pyoderma gangrenosum starts small  red bump skin  may resemble spider bite  days  bump can develop large  painful open sore  ulcer legs  may develop body  surgical sites  ulcers  may grow merge larger ulcer
pyoderma gangrenosum