Pyoderma Gangrenosum

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Disorder Subdivisions

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General Discussion

Pyoderma gangrenosum (PG) is an inflammatory skin disorder that is characterized by small, red bumps or blisters (papules or nodules) that eventually erode to form swollen open sores (ulcerations). The size and depth of the ulcerations vary greatly, and they are often extremely painful. In approximately 50 percent of cases, PG occurs secondary to another disorder such as inflammatory bowel disease. The exact cause of PG is unknown (idiopathic). Some researchers believe it may be an autoimmune disorder.


Pyoderma gangrenosum often begins as small, quick-spreading reddish or purple colored bumps or blisters. These small growths eventually develop into swollen, open sores (ulcerations) with a well-defined blue or violet-colored border. The size and depth of ulcerations vary. Ulcerations may spread, widen and deepen and may become extremely painful. In individual cases, ulcerations may continue to spread, remain unchanged, or heal without treatment (spontaneously).

Ulcerations can affect any part of the body and have been classified into four variants: classic, atypical/bullous, pustular, and vegetative.

Classic pyoderma gangrenosum most often occurs on the legs and is characterized by deep ulcerations. These lesions often begin as small pus-filled bumps (pustules) that enlarge and spread rapidly. This form of the disease is often very painful and may also affect the trunk, penis, head and neck areas.

Classic PG also occurs near surgical openings (stoma sites) in the body. This condition is referred to as peristomal pyoderma gangrenosum.

Atypical or bullous pyoderma gangrenosum is characterized by superficial blisters (bullae). This form of the disease most often affects the hands and is often associated with an underlying disorder especially hematological malignancy such as leukemia. Some cases that have been called atypical pyoderma gangrenosum actually represent Sweet syndrome.

Classic pyoderma gangrenosum is often characterized by the presence of pus and can begin with pustules. Pustular pyoderma gangrenosum is characterized by painful bumps (pustules) most often found on the arms and legs. These lesions eventually develop into ulcerations. This form is often associated with inflammatory bowel disease.

Vegetative pyoderma gangrenosum is characterized by chronic ulcerations that are not usually painful.

Additional findings sometimes associated with PG include fever, localized tenderness, joint pain (arthralgia), and a general feeling of ill health (malaise). PG may occur as a secondary characteristic of another disorder, most oftenulcerative colitis or Crohn's disease.


The exact cause of pyoderma gangrenosum is unknown (idiopathic) although it is suspected to be an autoimmune disease. Autoimmune disorders are caused when the body's natural defenses (e.g., antibodies) against foreign or invading organisms begin to attack healthy tissue for unknown reasons.

Approximately 50 percent of cases of pyoderma gangrenosum are associated with other disorders, especially the inflammatory bowel diseases ulcerative colitis or Crohn's disease. Additional disorders associated with pyoderma gangrenosum include rheumatoid arthritis, acute and chronic myelogenous leukemia, myeloid metaplasia, and paraproteinemias.

In some cases the development of pyoderma gangrenosum follows surgery or trauma. This condition is known as pathergy.

Affected Populations

Pyoderma gangrenosum affects women slightly more often than men. It occurs most often between the ages of 20 to 50 years. Infants or adolescents account for fewer than 4 percent of cases. One estimate places the incidence of PG at 1 in every 100,000 people in the United States.

Standard Therapies


No specific diagnostic tests exist for pyoderma gangrenosum. Diagnosis is made by excluding similar disorders based upon a thorough clinical evaluation, a detailed a patient history and a variety of tests such as surgical removal and microscopic evaluation of affected tissue (biopsy).


Treatment of PG consists of open wet dressings on the ulcers and topical application of anti-inflammatory creams and ointments such as corticosteroids. The skin must be protected from any other injury that could result in development of additional ulcers. In some cases, the grafting of new skin to the wound may be recommended once the inflammation is controlled.

Additional treatment of PG includes the administration of corticosteroid drugs such as methylprednisolone and prednisone. Corticosteroids may be administered by intramuscular injection or orally or by intralesional injection directly into the pyoderma gangrenosum.

According to some researchers, individuals with a past history of PG should receive preventive (prophylactic) treatment with corticosteroids before undergoing surgery because surgery may cause a recurrence of the disorder.

Immunosuppressive therapies (drugs that suppress the immune system) are sometimes used to treat people with pyoderma gangrenosum. Cyclosporine is effective for many patients. Azathioprine and cyclophosphamide are also immunosuppressive drugs that have been used to treat PG. In recent years drugs known as tumor necrosis factor inhibitors have been used very successfully to treat pyoderma gangrenosum. Infliximab and adalimumab have been most successful.

Antibacterial agents such as Dapsone may also be administered. In some cases surgical treatment of the underlying disorder such as ulcerative colitis has alleviate symptoms of pyoderma gangrenosum.

Additional treatment is symptomatic and supportive.

Investigational Therapies

Researchers are studying the use of the orphan drug thalidomide as a treatment for pyoderma gangrenosum. Thalidomide can have severe effects on a developing fetus and must be administered with extreme caution. More studies are needed to determine the long-term safety and effectiveness of this treatment. For more information, contact:

Celgene Corporation

7 Powder Horn Drive

Warren, NJ 07059

Tollfree: (888) 423-5436

Thalidomide is available in England under special license from Penn Pharmaceuticals of South Tredegar, South Wales.

Additional drugs that have been explored as potential treatments for individuals with PG include tacrolimus, ustekinumab, chlorambucil, clofazimine, mycophenolate mofetil, and intravenous immune globulin. More research is necessary to determine the long-term safety and effectiveness of these treatments for individuals with PG.

Information on current clinical trials is posted on the Internet at All studies receiving U.S. Government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222

TTY: (866) 411-1010


For information about clinical trials sponsored by private sources, contact:



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Jackson JM. Pyoderma Gangrenosum. Emedicine. Updated March 23, 2010. Accessed March 2, 2012.

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