Pyoderma gangrenosum is a chronic inflammatory skin disorder of unknown cause that causes large sores on the skin.
(See also Overview of Hypersensitivity and Reactive Skin Disorders.)
The cause is not known, but this disorder can develop after an injury or in people with certain disorders.
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 medications.
The cause of pyoderma gangrenosum is unknown, but people who have pyoderma gangrenosum tend to have certain underlying disorders, including inflammatory bowel disease, rheumatoid arthritis, cancers, and blood disorders.
In pyoderma gangrenosum, the immune system seems to be reacting to the skin itself. Unlike many inflammatory skin conditions that are caused by lymphocytes (a type of white blood cell), antibodies (proteins), or both, pyoderma gangrenosum involves abnormal function of another type of white blood cell called neutrophils (see Overview of the Immune System).
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).
Pyoderma gangrenosum typically affects people who are at least 55 years old.
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 sores 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 or buttocks. 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 minor trauma or a surgical procedure (such as a skin biopsy).
A sample of skin may need to be removed and examined under a microscope (called a skin biopsy), even though this procedure might worsen the problem temporarily.
Treatment of Pyoderma Gangrenosum
Dressings
Sometimes medications to suppress the immune system
Dressings that protect the skin from drying are applied to help heal the sores.
Surgical treatments are typically not done because they may worsen the sores.
