About Pyoderma Gangrenosum
What Is Pyoderma Gangrenosum?
Causes and Risk Factors for Pyoderma Gangrenosum
The exact cause of pyoderma gangrenosum is not fully understood. It is considered a rare, noninfectious inflammatory skin condition in which the immune system—especially neutrophils, a type of white blood cell—appears to become overactive and contribute to painful skin ulcers. Current research suggests that several factors may be involved:
- Immune system dysregulation: PG is not caused by an infection. It is thought to involve abnormal inflammation, including changes in both innate and adaptive immune responses.
- Neutrophil dysfunction: Neutrophils may collect in the skin and release inflammatory signals that damage tissue and contribute to ulcer formation.
- Genetic predisposition: Most cases are not inherited, but rare autoinflammatory syndromes and changes in genes such as PSTPIP1 can be associated with PG-like disease in some people.
- Pathergy: In some people with PG, minor skin injury, surgery, needle sticks, or trauma can trigger a new ulcer or worsen an existing one.
Risk factors and associated conditions for PG include:
- Underlying inflammatory or systemic conditions: About half of people with PG have an associated condition, such as inflammatory bowel disease, rheumatoid arthritis or other arthritis, blood disorders, or certain cancers of the blood.
- Skin trauma or surgery: PG may occur or flare at sites of injury, including surgical wounds, because of pathergy.
- Rare inherited or autoinflammatory syndromes: A small number of people develop PG in association with conditions such as pyogenic arthritis, pyoderma gangrenosum, and acne syndrome.
Pyoderma Gangrenosum Symptoms
What Does Pyoderma Gangrenosum Look Like When It Starts?
Pyoderma gangrenosum often starts suddenly as a small, painful area on the skin that may look like a red or purple bump, pustule, blister, or bruise-like spot. It can be mistaken at first for an insect bite, boil, or skin infection.
- Pain that may be severe or seem greater than expected based on the size of the sore
- A bump, blister, pustule, or nodule that breaks down into an open sore
- A rapidly enlarging ulcer with a red, purple, or bluish border
- An ulcer edge that looks raised, irregular, or undermined, meaning the skin at the edge overhangs the wound
Symptoms as Pyoderma Gangrenosum Progresses
As pyoderma gangrenosum progresses, the ulcer may enlarge quickly and become deeper. Symptoms may include:
- One or more painful ulcers, most often on the lower legs, but sometimes on the arms, trunk, around a stoma, or near a surgical wound
- A wound base that may look red, purple, gray, yellow, or necrotic
- Drainage from the ulcer, which may be clear, bloody, or pus-like even when infection is not the main cause
- New or worsening sores after skin injury, surgery, needle sticks, or trauma, a reaction called pathergy
- Fever, fatigue, or a general feeling of being unwell in some people
- Scarring after the ulcer heals, sometimes with a thin or crisscross pattern
Not everyone with pyoderma gangrenosum has the same symptoms. Because PG can worsen quickly and may be confused with an infection or another type of wound, a painful ulcer that is enlarging, has a purple or bluish edge, or appears after skin injury should be evaluated promptly by a healthcare professional.
How Pyoderma Gangrenosum Is Diagnosed
There is no single test that can confirm pyoderma gangrenosum. A healthcare professional, often a dermatologist, makes the diagnosis based on the appearance and behavior of the ulcer, a person’s medical history, and tests that help rule out infection and other causes of skin ulcers. Evaluation may include:
- History and physical exam: The healthcare professional will ask about how the ulcer started, how quickly it changed, pain, recent skin injury or surgery, and any history of inflammatory bowel disease, arthritis, blood disorders, or other inflammatory conditions. They will examine the ulcer for features that can suggest PG, such as tenderness, a red-purple or bluish undermined border, rapid enlargement, multiple ulcers, or worsening after trauma.
- Tests to rule out other causes: Lab tests and wound testing do not diagnose PG by themselves, but they can help check for infection, inflammation, blood disorders, vascular disease, or other conditions that can look similar. Testing may include:
- Wound swabs, tissue cultures, or other samples to check for bacterial, fungal, or mycobacterial infection
- A skin biopsy, usually taken from the edge of the ulcer, to support the diagnosis and help rule out other causes such as infection, vasculitis, cancer, or other inflammatory skin diseases. Biopsy findings are not specific for PG, but they may show a neutrophil-rich inflammatory pattern.
Because PG can look like an infection or other serious wound condition, prompt medical evaluation is important. Treatment approach may change if infection, poor blood flow, vasculitis, cancer, or another diagnosis is found. Follow up with your healthcare professional if the wound grows quickly, pain worsens, fever develops, or symptoms change.
Pyoderma Gangrenosum Treatment Options
Pyoderma gangrenosum treatment aims to reduce inflammation, control pain, protect the wound, prevent or treat infection when present, and help the skin heal. Treatment depends on the severity, size, location, and number of ulcers, whether the condition is worsening quickly, and whether another inflammatory or blood disorder is also present. Care is often coordinated by a dermatologist and may include:
Medications for pyoderma gangrenosum:
- Topical treatments: For smaller or milder ulcers, high-potency corticosteroid creams or ointments, tacrolimus ointment, or corticosteroid injections around the ulcer may help reduce local inflammation.
- Systemic corticosteroids: Oral or intravenous corticosteroids are commonly used when PG is more extensive, painful, rapidly worsening, or not controlled with topical treatment.
- Other immune-suppressing medicines: Cyclosporine is another commonly used systemic treatment. Other medicines, such as mycophenolate mofetil, methotrexate, azathioprine, or dapsone, may be considered in selected cases.
- Biologic therapy: Biologics, especially anti-TNF medicines such as infliximab or adalimumab, may be used for some people with severe, recurrent, or treatment-resistant PG, particularly when inflammatory bowel disease is also present. Other biologics may be considered by specialists in selected cases.
- Antibiotics: Antibiotics do not treat PG itself because PG is not primarily an infection. They may be used if there is a confirmed or strongly suspected secondary infection.
- Pain management: Pain can be significant and should be addressed as part of care. Options may include over-the-counter or prescription pain medicines, depending on the person’s symptoms and medical history.
Wound care and procedures for pyoderma gangrenosum:
- Gentle wound care: Dressings are used to protect the ulcer, manage drainage, support healing, and reduce pain. Wound care should be gentle because skin trauma can worsen PG in some people.
- Avoiding unnecessary wound trauma: Aggressive surgical debridement is usually avoided during active PG because injury to the skin can trigger pathergy, causing the ulcer to enlarge or new ulcers to form. Any procedure should be guided by specialists.
- Treatment of associated conditions: If PG is linked with inflammatory bowel disease, arthritis, a blood disorder, or another condition, treating that condition may be an important part of the overall plan.
- Additional therapies: Treatments such as hyperbaric oxygen therapy, negative pressure wound therapy, or surgery may be considered in selected cases, but they are not routine first-line treatments and should be used only with specialist guidance.
Treatment plans vary from person to person. A healthcare professional can help choose the safest approach, monitor for side effects, and adjust treatment as the ulcer heals or if symptoms change. Contact a healthcare professional promptly if the ulcer is rapidly enlarging, pain is worsening, fever develops, or there are signs of infection such as increasing redness, warmth, swelling, or drainage.