Overview

Pyoderma gangrenosum (pie-o-DUR-muh gang-ruh-NO-sum) is a rare condition that causes large, painful sores (ulcers) to develop on your skin, most often on your legs.

The exact causes of pyoderma gangrenosum are unknown, but it appears to be a disorder of the immune system. People who have certain underlying conditions, such as inflammatory bowel disease or arthritis, are at higher risk of pyoderma gangrenosum.

Pyoderma gangrenosum ulcers can develop quickly. They usually clear up with treatment, but scarring and recurrences are common.