Pyoderma gangrenosum (PG) is a skin disorder that may occur alongside ulcerative colitis (UC), a form of inflammatory bowel disease.

This article explores both conditions, their treatments, and their outlook. We look at various studies that show the link between them, their mutual symptoms, and differences in diagnosis.

PG is a type of skin disorder that may occur alongside other conditions or disorders. Inflammatory bowel disease (IBD) is the most common underlying condition in people with PG.

A 2021 case-control study looked at the probability of people with UC developing PG in comparison with those that do not have UC as an underlying condition. It found that people with UC had a 15-fold greater risk of developing PG.

Additionally, 5–12% of people with PG also tend to have UC and 1–2% have Crohn’s disease, another form of IBD.

Learn more about IBD from our hub.

PG lesions can occur anywhere on the body.

PG is an ulcer disorder. It can often result in:

  • fever
  • joint pain
  • small pustules, that either resolve or develop into ulcers which can go deep into the dermal layer of the skin and can be quite painful

PG can affect people from 11–89 years of age, with less than 5% of cases occurring in children. However, it is more common in people between 20 and 50 years old, especially women. One 2019 review found that PG cases affected women in up to 76% of all cases in some studies.

Symptoms of UC can differ from one individual to another. However, common ones include:

In severe cases of UC, symptoms can include:

Doctors diagnose UC by reviewing an individual’s medical and family history and performing physical and medical tests. These include:

  • questions about symptoms, smoking history, medications, and family medical history
  • checking blood pressure, heart rate, and temperature
  • using a stethoscope to listen to the abdominal sounds
  • pressing on the abdomen
  • digital rectal exams to analyze stool
  • blood tests
  • endoscopy of the large intestine to take a biopsy from the rectum or colon

These can help the doctor confirm the diagnosis and its severity and rule out other health conditions that may show similar symptoms to UC.

As for PG, the diagnosis can be quite similar. Doctors tend to use exclusion to eliminate all other potential medical reasons before arriving at PG as the condition that affects an individual.

The article, however, suggests criteria from a consensus of international experts for diagnosing PG. This includes:

  • checking the progression of ulcers
  • reviewing medical and family history
  • looking for other systemic diseases, including IBD and arthritis
  • taking skin biopsies
  • using chest X-rays to look for malignant types of PG

Treatment of PG can vary depending on its severity. Some doctors start with local wound care and topical treatments and go as far as biological therapies.

Other treatments include systematic drugs and steroids, such as:

Some of these drugs can also help treat UC. Medications with approval from the Food and Drug Administration (FDA) for UC include:

Furthermore, several studies show that some drugs can be useful in treating both UC and PG. In recent years, tumor necrosis alpha (TNF-α) inhibitors, such as Remicade (infliximab) and Humira (adalimumab), were effective for PG associated with IBD.

PG typically has no association with the disease activity of UC; however, PG may resolve with treatment of the IBD

Learn more about UC and skin rashes.

The NIDDK recommends treating PG and UC by reducing inflammation. Eating a balanced diet and being aware of what irritates bowel movements or the large intestine can help minimize exacerbation and remission.

PG and UC are both inflammatory conditions. UC typically presents issues with bowel movements, while PG shows up in the skin as deep painful ulcers.

Both conditions are treatable, sometimes with the same medications such as TNF-α inhibitors. In severe cases, biological therapy may be necessary in combination with drugs and care treatments.