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Pyoderma Gangrenosum


Julia Benedetti

, MD, Harvard Medical School

Last full review/revision Sep 2020| Content last modified Sep 2020
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Topic Resources

Pyoderma gangrenosum is a chronic inflammatory skin disease of unknown cause that results in large sores forming on the skin.

  • The cause is not known.

  • This disorder begins as small bumps or blisters that become open sores.

  • The diagnosis is usually based on the appearance of the sores.

  • Treatment includes dressings, creams, and drugs.

Pyoderma gangrenosum typically affects people who are 25 to 55 years old. Pyoderma gangrenosum can develop on areas of skin that have recently been injured or operated on. Thus, areas affected by pyoderma gangrenosum often worsen if they are biopsied (a sample of skin is removed for examination) or debrided (dead tissue is removed to clean the affected area).

Symptoms of Pyoderma Gangrenosum

Most often, pyoderma gangrenosum begins as a red bump that may resemble a pimple or an insect bite. Less often, it begins as a blister. The bump or blister then becomes an open, painful sore (ulcer) that expands rapidly. The sores have a raised border that is dusky or purple. The sores can grow together to form larger sores. People often are left with scars after ulcers heal. People commonly have fever and a general feeling of illness (malaise).

Pyoderma gangrenosum can also develop at other locations, such as in the abdominal wall around a colostomy or ileostomy opening in people who have inflammatory bowel disease, or on the genitals. In some people with pyoderma gangrenosum, areas other than the skin, such as the bones, lungs, heart, liver, or muscles, are affected.

Diagnosis of Pyoderma Gangrenosum

  • A doctor's evaluation

Doctors diagnose pyoderma gangrenosum by the appearance of the sores and by ruling out other diseases that cause sores to form on the skin. The diagnosis of pyoderma gangrenosum is strongly suggested if the sores worsen after they are debrided.

Treatment of Pyoderma Gangrenosum

  • Dressings

  • Corticosteroids or tacrolimus applied to the skin

  • Sometimes drugs to suppress the immune system

Dressings that protect the skin from drying are applied to help heal the sores.

Potent corticosteroid creams or tacrolimus can be directly applied to sores that are new and not deep. Prednisone taken by mouth is given to people severely affected by the disease.

Cyclosporine can be very effective, particularly for people whose disease is progressing rapidly. Dapsone, azathioprine, cyclophosphamide, methotrexate, clofazimine, thalidomide, mycophenolate mofetil, and minocycline are other treatment options.

Surgical treatments are typically not done because they may worsen the sores.

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Test your knowledge
Psoriasis is a common chronic disease affecting 1 to 5% of the population worldwide. It causes distinctive raised, red patches with silvery scales. A border between the patch and normal skin is known as “psoriatic plaque.”  Which of the following is the reason these patches of plaque form?
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