Pyoderma Gangrenosum

Pyoderma gangrenosum is a rare and painful skin condition where small bumps or blisters rapidly turn into large, open sores that can be difficult to diagnose and treat, often affecting people with other health conditions like inflammatory bowel disease or arthritis.

Table of contents

• What is pyoderma gangrenosum?
• Who is affected?
• Symptoms
• Causes
• Diagnosis
• Treatment
• Outlook and complications
• Living with pyoderma gangrenosum

What is pyoderma gangrenosum?

Pyoderma gangrenosum is a rare skin disorder where painful sores develop on the skin. Despite its name, pyoderma gangrenosum is not caused by infection or gangrene (tissue death from lack of blood flow). Instead, it is an autoinflammatory disorder, meaning the body’s immune system attacks healthy tissue in your own body^[1][2].

The condition typically starts with a small bump on the skin that might look like a spider bite or insect bite. Within days, this small bump can turn into a large and painful open sore, called an ulcer. The ulcer can grow and widen rapidly. A distinctive feature is that the edge of the ulcer is usually purple or blue in color and appears raised or overhanging^[3][4].

Pyoderma gangrenosum is not contagious. You cannot spread it to another person through skin-to-skin contact^[3][6].

Who is affected?

Pyoderma gangrenosum is uncommon. It affects approximately 1 in every 100,000 people in the United States^[3]. The condition can affect people of any age, but it is rare in children, with less than 5% of cases occurring in childhood. Most cases develop in people between the ages of 40 and 50, though it most commonly affects women between the ages of 20 and 50^[2][3].

You may be more likely to develop pyoderma gangrenosum if you have certain other conditions. More than half of people with pyoderma gangrenosum have other health problems^[4]. The most common associated conditions include:

• Rheumatoid arthritis (a condition causing joint pain and swelling)
• Ulcerative colitis (inflammation of the large intestine)
• Crohn’s disease (inflammation of the digestive tract)
• Blood disorders, such as leukemia or lymphoma
• Chronic active hepatitis (liver inflammation)

Pyoderma gangrenosum is associated with ulcerative colitis in 5% to 12% of cases and with Crohn’s disease in 1% to 2% of cases^[2][4]. However, about half of those affected by pyoderma gangrenosum have none of these associated risk factors^[4].

Symptoms

Pyoderma gangrenosum usually starts quite suddenly. The main symptom is a large, painful ulcer on your skin. It most often appears on the legs, but it may develop anywhere on the body, including the arms, chest, genitals, or neck^[1][3].

The condition typically begins as a small bump, pustule (pus-filled blister), red bump, or blood blister on the skin. The skin then breaks down, resulting in an ulcer. This ulcer can deepen and widen rapidly, sometimes within days^[1][4].

Key features of pyoderma gangrenosum ulcers include:

• Distinctive purple, blue, or violet edges that appear raised or undermined
• The ulcer may leak fluid or pus
• Severe pain around the sore
• One or multiple ulcers may develop at the same time
• Ulcers can merge together if there are two or more

On white skin, the pyoderma gangrenosum ulcer will often be blue or purple around the edge. On brown or black skin, the skin around the ulcer may be darker than the rest of the skin^[6].

Sometimes pyoderma gangrenosum appears around surgical sites, near cuts or grazes, or around a stoma (a surgical opening made in the body, such as for a colostomy). This is known as peristomal pyoderma gangrenosum^[4][6].

Other symptoms may include:

• Stiff joints
• Aching and painful muscles
• Fever
• Joint pain

Causes

Medical experts don’t know exactly what causes pyoderma gangrenosum. The condition is thought to be an autoinflammatory disease due to some form of neutrophil dysfunction, where certain white blood cells that normally fight infection behave abnormally^[2][4]. The immune system appears to attack healthy tissue, leading to inflammation and skin breakdown.

The disease appears to involve problems with the immune system. Research has found that lesions of pyoderma gangrenosum contain increased levels of inflammatory substances called cytokines, including interleukin (IL)-8, IL-1β, IL-6, and tumor necrosis factor alpha^[5].

There may be a genetic component to the disease. Some cases are associated with genetic mutations, and some studies suggest that it may be passed down through families^[1][4].

A distinctive feature of pyoderma gangrenosum is something called pathergy. This means that injury to the skin is a common trigger. New sores can develop at sites of trauma, such as cuts, scrapes, or surgical wounds. Getting a cut or other skin wound can bring on new sores in people who already have pyoderma gangrenosum^[1][4].

Certain drugs are occasionally implicated as triggers, especially cocaine, isotretinoin (a medication for acne), propylthiouracil (a thyroid medication), and sunitinib (a cancer medication)^[4].

Diagnosis

Pyoderma gangrenosum can be challenging to diagnose. Diagnosis is made by excluding other similar skin disorders and combining clinical assessment with certain investigations. No single test can confirm a diagnosis of pyoderma gangrenosum^[2][3].

Your healthcare professional will talk with you about your symptoms and medical history and conduct a physical exam. Correct and early diagnosis is key to effective treatment. You may be referred to a specialist in skin conditions, called a dermatologist^[10].

To rule out other conditions that have similar symptoms, you may need several tests:

• Blood tests to exclude certain conditions that can be associated with pyoderma gangrenosum
• Swabbing of the wound to rule out infection
• Urine and stool tests
• A chest X-ray
• A colon exam
• A skin biopsy (a procedure to remove a small sample of tissue for testing in a lab)

The skin biopsy is helpful in ruling out other causes of skin ulceration. Pyoderma gangrenosum does not have a specific appearance under the microscope, but there is usually an abundance of white blood cells called neutrophils^[2][7].

Your doctor will need to exclude other conditions that can look like pyoderma gangrenosum, such as venous leg ulcers, inflammation of blood vessels or skin, infection, injury, and cancer^[7]. Misdiagnosis and delayed diagnosis are common. Studies show that up to 39% of patients who initially received a diagnosis of pyoderma gangrenosum have an alternative diagnosis^[5].

Treatment

Treatment of pyoderma gangrenosum is aimed at reducing swelling, controlling pain, and helping skin sores heal. Medicines are the most common treatment. Your treatment depends on your health, how many sores you have, how deep they are, and how fast they’re growing^[10].

Pyoderma gangrenosum is often difficult to treat and may take some time to heal. More than one treatment may need to be tried. Sores can take weeks or months to heal, and it’s common for new ones to develop^[7][10].

Topical treatments

For mild disease, treatment may include:

• Creams or ointments, including corticosteroids (anti-inflammatory medications) and calcineurin inhibitors such as tacrolimus
• Bandages and dressings to protect the ulcer

Systemic treatments

More severe disease is often managed with medications taken by mouth or by injection. The most common treatment for pyoderma gangrenosum is daily doses of corticosteroids. These may be applied to the skin, injected into the wound, or taken by mouth. The pill form is called prednisone^[10].

Other systemic therapies include:

• Immunosuppressive medicines such as cyclosporine, mycophenolate mofetil, or azathioprine. These work by reducing your body’s natural immune response
• Antibiotics such as dapsone or minocycline
• Biologic therapies such as infliximab or adalimumab. These are targeted therapies that work by blocking specific parts of the immune system, particularly tumor necrosis factor-alpha
• Newer treatments including interleukin inhibitors and Janus kinase (JAK) inhibitors

Corticosteroids and/or cyclosporine remain the systemic treatments of choice for most patients with pyoderma gangrenosum. However, biologics have now become the drug of choice in certain scenarios, particularly in patients with underlying inflammatory conditions like inflammatory bowel disease^[9].

Using corticosteroids for a long time or in high doses may cause severe side effects. To avoid these side effects, steroids may be used only for short periods of time to control the sores, and other medicines may be added^[10].

What to avoid

Skin grafts and surgery are generally not treatment options as they often fail and may cause enlargement of the ulcer due to pathergy^[7][13]. Surgery should be avoided if possible because of the pathergic phenomenon that may occur^[13].

In patients with an associated underlying disease, effective therapy for the associated condition may be linked to control of the skin condition as well^[13].

Outlook and complications

The prognosis for patients with pyoderma gangrenosum is generally good. However, the disease may recur, and residual scarring is common. Deep ulcers heal with scarring, and this is sometimes with a characteristic criss-cross pattern or wrinkled appearance^[4][8].

The healed scars may appear darker than the surrounding skin (hyperpigmented), pale, thin, or pitted. People with brown or Black skin have a higher risk of long-term skin color changes^[7].

Possible complications include:

• Infection of the ulcer
• Uncontrolled pain
• Scarring
• Changes in skin color after the affected skin heals

Studies show that up to 70% of people with pyoderma gangrenosum often have more than one illness or disease occurring at the same time. A combination of pyoderma gangrenosum and other systemic diseases—including rheumatoid arthritis, inflammatory bowel disease, and blood disorders—may increase the likelihood of death by 30%^[3].

Most patients with pyoderma gangrenosum improve with initial immunosuppressive therapy and require minimal care afterwards. However, many patients follow a difficult course, and multiple therapies may fail. Some patients demonstrate pathergy, which means that protection of the skin from trauma may prevent a recurrence of the disease^[8].

Living with pyoderma gangrenosum

Living with pyoderma gangrenosum can have a profound impact on quality of life. The condition affects patients in multiple ways throughout disease progression, remission, and recurrence^[15].

Experiences of delayed diagnosis and misdiagnosis are common, causing distress and resulting in unnecessary treatments including surgery. The severe pain associated with the ulcers disrupts sleep and limits daily activities. This can erode patients’ sense of self-control and perpetuate depressed mood and anxiety^[15].

The physical challenges are significant. Patients may experience mobility problems, difficulty walking, and the need to use walking aids. The pain can be so severe that it requires strong pain medication, including morphine. Many patients find that they cannot work due to the severity of their condition^[16].

The ulcers can also affect social functioning and relationships. The appearance of the wounds, along with the need for dressings and frequent clinic visits, can impact how patients interact with others and participate in daily life.

Self-care and prevention

You cannot prevent the first instance of pyoderma gangrenosum. However, if you have the condition, you can help prevent new sores by protecting your skin from injury. Injury or trauma to the skin, including from surgery, can cause new sores to form^[1].

It also may help to control any other condition you have that’s related to pyoderma gangrenosum. For some people, pyoderma gangrenosum will improve after treatment for their other systemic diseases^[3].

Management should include:

• Early specialist referral if you suspect you have this condition
• Proper wound care as directed by your healthcare team
• Pain management strategies
• Understanding disease expectations and what to watch for
• Regular follow-up with your healthcare team

If you develop a skin ulcer that’s not getting better, or if you develop a painful, rapidly growing skin wound, see a healthcare professional promptly^[6].