Pyoderma gangrenosum
An ulcerating condition of the skin leading to hollowed-out areas (ulcers) with heaped-up borders and a typical appearance.
The lesion(s) usually begin as soft raised nodules on the skin which proceed to ulcerate.
The ulcers enlarge and the skin at the edge becomes purple-red.
The ulcers can become quite large.
Pyoderma gangrenosum is thought to be mediated by the immune system, but the exact sequence of events is unknown.
It is associated with several other diseases, including ulcerative colitis, Crohn disease, rheumatoid arthritis, leukemia, and cryoglobulinemia.
Pyoderma gangrenosum is usually responsive to treatment with corticosteroids.