What Causes Pyoderma Gangrenosum, and Is It Hereditary?

It is completely normal to wonder why you developed pyoderma gangrenosum (PG), if you could have prevented it, or if it can be passed to your children. The most important thing to know is that PG is not your fault, it is not contagious, and it is not caused by poor hygiene ^[1][2]. Despite the word “pyoderma” (which traditionally meant a pus-producing infection), PG is an inflammatory disorder, not a bacterial infection ^[1]. It is thought to result from a dysregulated immune system, though the exact cause is not fully understood ^[3]. While the exact trigger isn’t always clear, sporadic (ordinary) PG is usually not inherited in a simple, predictable way, meaning it is unlikely you will pass it directly to your children ^[4][5].

The Immune System Connection

PG is currently understood as a disease of immune dysregulation—meaning the body’s natural defense system does not control inflammation properly and mistakenly targets the skin ^[3]. In PG, neutrophils (a type of white blood cell that normally fights infection) become overactive and accumulate in the skin ^[6]. This causes intense inflammation and tissue breakdown, leading to painful ulcers.

This process is driven by an imbalance in cytokines, which are chemical messenger proteins that coordinate inflammation in the body ^[4]. Specific cytokines involved in PG include interleukins and tumor necrosis factor (TNF) ^[7]. Because PG is a problem with internal immune signals, you cannot catch it from someone else, and no amount of washing or scrubbing could have prevented it ^[1].

Safety Note: Because PG involves overactive inflammation, injury to the skin—such as cuts, surgery, needle procedures, or sharp medical debridement (cleaning out a wound)—can trigger a new ulcer or make an existing one larger. This phenomenon is called pathergy ^[8][9]. Always tell your medical team you have PG so they can use gentle, PG-aware wound care ^[10].

Associated Systemic Diseases

Often, the immune imbalance that occurs in PG is linked to other conditions in the body. About half of people with PG, and in some studies more, have an associated systemic (body-wide) inflammatory or blood disorder ^[11]. However, many people with PG have no other identifiable disease.

The most commonly associated conditions include:

• Inflammatory Bowel Disease (IBD): Such as Crohn’s disease or ulcerative colitis ^[11].
• Inflammatory Arthritis: Including rheumatoid arthritis or arthritis associated with IBD ^[11].
• Blood Disorders: Such as myelodysplastic syndrome (MDS, a condition where the bone marrow does not make enough healthy blood cells) or monoclonal gammopathy of undetermined significance (MGUS, a harmless abnormal protein in the blood that sometimes requires monitoring) ^[12].

Having these conditions alongside PG does not mean they definitely caused your PG ^[11]. Sometimes, PG is the first sign of one of these conditions ^[13]. This is why your doctor will likely ask about your overall health and may order specific blood tests. Testing is highly individualized; for example, a gastrointestinal evaluation or colonoscopy is not universally required unless you have specific bowel symptoms or age-appropriate screening needs.

Is Pyoderma Gangrenosum Hereditary?

For the vast majority of people, PG is not considered a traditional inherited disease ^[4]. A review of hundreds of published PG cases found that less than 2% of people with PG had a family member who also had the condition ^[5]. While you might carry some genetic traits that make your immune system more susceptible to inflammation, you are not simply passing a “PG gene” to your children.

However, in very rare cases, PG can be part of a distinct genetic syndrome. For example:

• PAPA Syndrome (Pyogenic Arthritis, Pyoderma gangrenosum, and Acne) is a rare inherited disorder linked to mutations in a specific gene (PSTPIP1) ^[14]. It can be passed from parent to child in a predictable pattern. “Pyogenic arthritis” in this syndrome means recurrent sterile joint swelling, not a bacterial joint infection ^[15].
• PASH Syndrome (Pyoderma gangrenosum, Acne, and Hidradenitis Suppurativa, a condition causing painful lumps under the skin) is another rare clinical syndrome. Unlike PAPA, PASH has a complex genetic basis that is not fully understood and is usually not inherited in a simple parent-to-child pattern ^[16].

Routine genetic testing is not recommended for most adults with typical PG. However, your doctor may suggest an evaluation by a geneticist if your PG started in early childhood, occurs alongside recurrent sterile arthritis, severe acne, or hidradenitis suppurativa, or if you have a strong family history of these specific issues ^[7][17].