Pyoderma Gangrenosum

Pyoderma gangrenosum is a rare and painful skin condition that causes large, open sores called ulcers. Despite its name, this condition is not an infection and is not contagious. It often begins as a small bump or blister that rapidly grows into a deep wound, requiring prompt medical attention to prevent complications.

Table of contents

• What is pyoderma gangrenosum?
• Who gets pyoderma gangrenosum?
• What causes pyoderma gangrenosum?
• Symptoms and appearance
• How is it diagnosed?
• Treatment options
• What to expect

What is pyoderma gangrenosum?

Pyoderma gangrenosum is a rare inflammatory skin disorder that causes painful, open sores on the skin^[1]. The name can be confusing because despite what it sounds like, this condition is neither caused by infection nor related to gangrene (tissue death from lack of blood supply)^[2].

Pyoderma gangrenosum belongs to a group of conditions called neutrophilic dermatoses. These are conditions where neutrophils, which are a type of white blood cell that normally protect the body from infections, quickly gather in affected skin tissue and cause inflammation and damage^[3].

The condition is rare, affecting approximately 3 to 10 people per million each year^[4]. It can occur at any age, but is most common in people between 20 and 50 years old, with women being affected more often than men^[4].

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Who gets pyoderma gangrenosum?

About half of people with pyoderma gangrenosum have no known underlying condition^[7]. However, the condition is frequently associated with other diseases. You may be more likely to develop pyoderma gangrenosum if you have^[1][2]:

• Inflammatory bowel disease, such as ulcerative colitis or Crohn’s disease
• Rheumatoid arthritis
• Certain blood disorders, including leukaemia, myelodysplastic syndrome, or polycythemia vera
• Chronic hepatitis
• Behçet’s disease
• Some cancers

In people with inflammatory bowel disease, pyoderma gangrenosum represents the second most common skin manifestation, occurring in 1 to 3 percent of these patients. It is more commonly a complication of ulcerative colitis compared to Crohn’s disease^[5].

The condition is not passed down through families and cannot be spread from person to person through contact^[2].

What causes pyoderma gangrenosum?

The exact cause of pyoderma gangrenosum is not fully understood. It is thought to be an autoinflammatory disease, meaning the body’s immune system produces an excessive response to an internal trigger, causing inflammation and tissue damage^[5].

The condition appears to involve dysfunction of neutrophils, with certain immune system chemicals called cytokines and T lymphocytes playing a role. There may be a genetic predisposition in some cases^[5].

In about 30 percent of cases, pyoderma gangrenosum develops after an injury to the skin, such as a cut, insect bite, needle stick, or surgical wound. This process is called pathergy^[6][8]. The skin injury triggers an abnormal inflammatory response that leads to the formation of an ulcer.

Certain medications have occasionally been linked to triggering pyoderma gangrenosum, including cocaine (especially when contaminated with levamisole), isotretinoin, propylthiouracil, and some cancer drugs^[5].

Symptoms and appearance

Pyoderma gangrenosum usually starts quite suddenly. It often begins as a small, red or purple bump, pustule, or blood blister on the skin. At this early stage, it may look like an insect bite or pimple^[1][5].

Within days, the skin breaks down and the bump rapidly expands into a painful, open sore. The ulcer can deepen and widen very quickly. A characteristic feature is that the edge of the ulcer typically appears purple or blue (on white skin) or darker than the surrounding skin (on brown or black skin), with an undermined border, meaning the edge overhangs and lacks support underneath^[2][6].

The ulcer may ooze fluid or pus. One of the most troubling symptoms is severe pain that seems out of proportion to the size of the wound. This pain often disrupts sleep and limits daily activities^[17].

The most common location for pyoderma gangrenosum is the legs, though it can appear anywhere on the body, including the arms, trunk, face, genital area, or around surgical sites or stomas (surgical openings in the abdomen)^[1][2].

Other symptoms that may accompany the skin ulcers include^[2]:

• Stiff joints
• Aching and painful muscles
• Fever
• General feeling of being unwell

There are several different forms of pyoderma gangrenosum. The most common is the ulcerative type described above. Other variants include bullous (with fluid-filled blisters), pustular (with multiple small pus-filled bumps), and vegetative (with more superficial wounds and a less aggressive course)^[4][6].

• Skin
• Lower legs
• Feet
• Trunk

How is it diagnosed?

Diagnosing pyoderma gangrenosum can be challenging because there is no single test that can confirm it^[7][10]. The diagnosis is based on a combination of examining the skin, reviewing your medical history, excluding other possible causes, and performing certain tests.

Your healthcare professional will need to rule out other conditions that can look similar to pyoderma gangrenosum, such as^[2][7]:

• Infections of the skin
• Venous leg ulcers
• Inflammation of blood vessels (vasculitis)
• Skin cancers or tumors
• Injuries to the skin

To help make the diagnosis, your doctor may perform several tests^[7][10]:

• A swab of the wound to check for infection
• A skin biopsy, which involves removing a small sample of tissue to examine under a microscope. While pyoderma gangrenosum doesn’t have a specific appearance under the microscope, the biopsy helps rule out other conditions. It typically shows an abundance of neutrophils in the tissue
• Blood tests to check for associated conditions such as inflammatory bowel disease, rheumatoid arthritis, or blood disorders
• Urine and stool tests if needed

Early and correct diagnosis is crucial for effective treatment. One important clue that suggests pyoderma gangrenosum is if an ulcer worsens or grows larger after surgical attempts to remove tissue or repair the wound^[6].

Treatment options

Treating pyoderma gangrenosum can be difficult, and healing may take a long time. The treatment depends on how severe the condition is^[2][10]. Getting the condition under control quickly is important to prevent further damage to the skin^[9].

Surgery to remove the ulcers or skin grafts are generally not recommended because they often fail and may make the ulcer worse due to pathergy (the tendency for new wounds to trigger more disease)^[2][7].

Topical treatments

For mild cases, treatment with creams or ointments applied directly to the skin may be sufficient. These include^[2][7]:

• Corticosteroid creams or ointments, which reduce inflammation
• Calcineurin inhibitors such as tacrolimus

Proper wound care with modern dressings is also important. Clean bandages and dressings help protect the ulcer, minimize pain, and reduce the risk of secondary infections^[4].

Systemic treatments

More severe cases require medicines taken by mouth or given by injection. The most commonly used treatments are^[10][11]:

Corticosteroids are the most common first-line treatment. These may be taken as pills (such as prednisone), injected directly into the wound, or given intravenously. They work by reducing inflammation. However, using corticosteroids for a long time or in high doses can cause serious side effects, so doctors try to use them for the shortest time possible^[10].

Cyclosporine is often used as an alternative or in combination with corticosteroids. This is an immunosuppressive drug that reduces the body’s immune response^[11].

Other immunosuppressive medicines that may be used include^[7][9]:

• Mycophenolate mofetil
• Azathioprine
• Cyclophosphamide
• Tacrolimus

Antibiotics such as dapsone or minocycline may be prescribed, though these work more as anti-inflammatory agents than as infection fighters^[7].

Biologic therapies

In recent years, newer biologic therapies have shown promise for treating pyoderma gangrenosum, particularly in patients who don’t respond to other treatments or who have underlying inflammatory conditions^[11]. These include:

• Tumor necrosis factor (TNF) inhibitors such as infliximab, adalimumab, etanercept, certolizumab, and golimumab. These block a specific inflammatory chemical in the body and have been particularly effective in patients with inflammatory bowel disease^[4][10]
• Interleukin inhibitors, which target other inflammatory pathways^[11]
• JAK inhibitors such as upadacitinib, which have shown success in some patients^[15]

Pain management

Because pyoderma gangrenosum causes severe pain, effective pain control is an essential part of treatment. This may include prescription pain medications^[17].

If you have an underlying condition such as inflammatory bowel disease or rheumatoid arthritis, treating that condition effectively may help control the pyoderma gangrenosum as well^[1].

What to expect

The course of pyoderma gangrenosum is unpredictable. Without treatment, ulcers may continue to enlarge, remain unchanged, or slowly heal on their own. Treatment is usually successful in stopping the progression of the ulcers, but complete healing may take weeks or months^[5][10].

Deep ulcers often heal with scarring. The scars may have a characteristic criss-cross pattern or may appear thin, wrinkled, darker, or lighter than the surrounding skin^[5][7].

It is common for new sores to develop even during treatment. The condition can recur, especially if the underlying health problem is not fully controlled^[1][9].

Pyoderma gangrenosum can have a significant impact on quality of life. The severe pain can disrupt sleep and limit daily activities. The visible wounds and long healing process can affect mental health, leading to depression and anxiety. Some patients experience difficulty with mobility, particularly when ulcers are on the legs^[17].

Living with pyoderma gangrenosum requires ongoing care and monitoring. Important steps include^[9]:

• Maintaining good wound hygiene
• Avoiding trauma to the skin when possible
• Managing any underlying health conditions
• Working closely with a dermatologist or rheumatologist for long-term care
• Staying alert for signs of infection in the wounds

If you notice a painful skin ulcer that is rapidly growing, or if a wound is not healing despite proper care, seek medical attention immediately^[1]. Early diagnosis and treatment can help prevent complications and improve outcomes.