Pyoderma gangrenosum is a rare, destructive inflammatory skin disease of which a painful nodule or pustule breaks down to form a progressively enlarging ulcer. Lesions may occur either in the absence of any apparent underlying disorder or in association with other diseases, such as ulcerative colitis, Crohn's disease, polyarthritis (an inflammation of several joints together), gammopathy, vasculitis, leukemia, and other conditions. Each year in the United States, pyoderma gangrenosum occurs in about 1 person per 100,000 people.

Pyoderma gangrenosum belongs to a group of autoinflammatory skin diseases called neutrophilic dermatoses. Neutrophils are a type of white blood cell or leukocyte which form an early line of defense against bacterial infections. Ulcerations associated with pyoderma gangrenosum may occur after trauma or injury to the skin, a process called pathergy. Treatment involves wound care and the use of anti-inflammatory agents, including antibiotics, corticosteroids, immunosuppressants, and biologics. 

Although antibiotics are often prescribed prior to having a correct diagnosis (and may be continued if there is a secondary infection or surrounding cellulitis), antibiotics are generally not helpful for treating uncomplicated cases of pyoderma gangrenosum. The best documented treatments are systemic corticosteroids and cyclosporin A. Smaller ulcers may be treated with strong topical steroid creams, steroid injections, special dressings, oral anti-inflammatory antibiotics, and/or other therapies. More severe cases typically require immunosuppressive therapy (used to decrease the body's immune responses). Combinations of steroids with cytotoxic drugs may be used in resistant cases. There has reportedly been rapid improvement of pyoderma gangrenosum with use of anti-tumor necrosis alpha therapy (such as infliximab), which is also used to treat Crohn's disease and other conditions. Skin transplants and/or the application of bioengineered skin is useful in selected cases as a complementary therapy to immunosuppressive treatment. The use of modern wound dressings is helpful to minimize pain and the risk of secondary infections. Treatment for pyoderma gangrenosum generally does not involve surgery because it can result in enlargement of the ulcer; however, necrotic tissue (dying or dead tissue) should be gently removed.

More detailed information about the treatment of pyoderma gangrenosum is available on the Treatment and Medication pages of Medscape Reference.