What is Cutaneous Crohn Disease?
Crohn’s disease is a type of inflammatory bowel disease that causes inflammation in the digestive tract. It can also affect other parts of the body outside the gut, which are known as extra-intestinal manifestations. Almost half of all people with Crohn’s disease will experience at least one symptom outside their digestive tract. The skin is the most common area affected outside the digestive system. Other frequently affected areas are the eyes, joints, and liver and bile passage system. Interestingly, for around a quarter of patients, these extra-intestinal manifestations can present before Crohn’s disease is officially diagnosed.
What Causes Cutaneous Crohn Disease?
Although we don’t completely understand what causes Crohn’s disease, it’s widely believed that it happens when certain “triggers” like infections, environmental factors, or immune responses happen in someone who’s genetically prone to the disease. This causes a long-term inflammation that may be caused by certain immune system pathways being overly activated, along with high levels of specific proteins involved in the inflammatory response.
Some genetic changes can also affect the body’s initial immune response. For instance, an altered TRAF3IP2 gene could make a person more likely to have skin-related symptoms in their Crohn’s disease. Other studies have shown changes in the gut bacteria (either in its makeup or its diversity) in people with Crohn’s disease. However, we also don’t fully understand why skin symptoms occur in Crohn’s disease.
Nevertheless, there are three widely accepted categories that help us understand and categorize these skin symptoms:
– Specific lesions: These are skin symptoms that, when looked at under a microscope, show signs of Crohn’s disease. This category includes skin symptoms caused by the bowel disease spreading directly to the skin and Crohn’s disease skin symptoms that occur in areas far away from the digestive tract.
– Reactive lesions: These are inflammatory skin symptoms that don’t show the same signs under the microscope.
– Associated lesions: These skin symptoms likely happen because of shared genes or as a response to a long-term inflammation.
Some experts suggest a fourth category for skin symptoms that happen because of Crohn’s disease treatment, particularly with certain types of medication.
Risk Factors and Frequency for Cutaneous Crohn Disease
Crohn’s disease can start at any age, but it’s most often diagnosed in young adults, aged 15 to 30. Interestingly, between 25% to 35% of all cases are diagnosed in people under 18. The number of people with Crohn’s disease has been going up, especially in developed countries. In the United States, about 246 out of every 100,000 people have Crohn’s disease. Between 20% to 33% of these people experience skin-related symptoms of their disease.
Signs and Symptoms of Cutaneous Crohn Disease
Crohn disease is a complex condition and the symptoms can vary greatly. Some common manifestations include abdominal pain, loss of appetite, weight loss, diarrhea, blood in stool, malnutrition, fatigue, fever, and bowel obstruction due to narrowing of the intestine. Crohn disease can affect any part of the digestive tract ranging from the mouth to the rectum, but it primarily impacts the small intestine and colon.
In addition to digestive symptoms, Crohn disease can also impact the skin. These skin signs can sometimes appear before a formal diagnosis of the disease is made. You can categorize these skin manifestations of Crohn disease into four categories:
- Specific lesions: skin changes that when biopsied, show the same types of cells seen in Crohn disease.
- Reactive lesions: skin changes that don’t look like Crohn disease under a microscope but are thought to have a similar cause.
- Associated lesions: skin changes that are likely due to shared genetic factors or as a result of chronic inflammation.
- Treatment-induced: skin changes that are most commonly associated with the treatment of Crohn disease with anti-TNF biologics.
The presence, absence, or severity of these skin symptoms might help doctors monitor the progress of Crohn disease, particularly in relatively symptom-free patients who show signs of oral ulcers or erythema nodosum.
Testing for Cutaneous Crohn Disease
The diagnosis of Crohn’s disease usually involves inspecting the lining of the intestines through a medical procedure called endoscopy, along with taking a small tissue sample, or a biopsy. These tests help doctors to identify changes in the tissue and irregularities in the tiny glands called crypts in the gut’s lining, which are typical in Crohn’s disease. Sometimes, doctors may also use blood tests as part of the diagnosis process.
Treatment Options for Cutaneous Crohn Disease
Crohn’s disease can result in a variety of skin-related conditions, and treatments can vary depending on the specific type of skin condition. Here is some general information for each type.
Firstly, specific lesions. These are skin conditions that are directly related to Crohn’s disease. For instance, the disease may directly cause some skin problems when inflammation from the bowel spreads to the skin, which usually requires surgical treatment. Meanwhile, another type of Crohn’s-related skin condition, metastatic Crohn disease, can be difficult to treat. There are limited options available, including the use of drugs that modify the immune response, such as anti-TNF biologics or corticosteroids.
Reactive lesions are another type of skin issue related to Crohn’s disease. One type is called Pyoderma gangrenosum (PG). The goal of treatment is to reduce inflammation, manage pain, and control Crohn’s disease, which often parallels the progression of PG. Patients may need regular wound care and medications including corticosteroids, if the PG doesn’t respond to that, cyclosporine or anti-TNF agents may be considered. But it’s important to note that remission may be temporary and some patients may experience recurrent disease.
Sweet’s syndrome is another form of reactive lesions. These lesions typically resolve on their own in 1-3 months without causing any scarring. However, recurrences are common. Corticosteroids can help manage symptoms, and for localized disease, steroids may be applied topically.
Associated lesions occur due to shared genetic factors or inflammatory response. Erythema nodosum, a skin condition that tends to mirror the activity of Crohn’s in the intestine, usually resolves by itself without scarring. The main way to treat it involves managing the underlying Crohn’s disease. If the condition is severe or persists, corticosteroids or possibly anti-TNF agents may be used.
Some Crohn’s patients also develop oral lesions, the prevalence and severity of these oral issues are typically tied to the activity of Crohn’s. The initial treatment approach focuses on managing the overall Crohn’s and providing supportive oral care such as using antiseptic and painkilling mouthwashes. Local corticosteroids may also be applied.
Lastly, treatment-induced skin conditions are often linked to the use of anti-TNF biologics in treating Crohn’s disease. If a patient develops this type of lesion, discontinuation of the anti-TNF treatment typically helps to resolve it, but it’s not always necessary. Instead, various topical treatments such as corticosteroids, emollients, or vitamin D analogs can be utilized, as can phototherapy.
What else can Cutaneous Crohn Disease be?
There are situations where skin conditions that are not associated with granulomas can cause skin damage or changes. These conditions include:
- Pyoderma gangrenosum, a rare skin condition causing painful sores
- Sweet’s syndrome, also known as neutrophilic dermatosis, which is characterized by painful skin lesions
- Pyodermatitis-pyostomatitis vegetans, which is linked to painful sores kind of like snail-track ulcers
- Erythema multiforme, a skin reaction usually triggered by infections
- Erythema nodosum, resulting in red, tender lumps under the skin
- Acneforms eruptions, which include severe acne, hidradenitis suppurativa (a long-term skin condition), and folliculitis (inflamed hair follicles)
- Palisaded neutrophilic and granulomatous dermatitis, a rare skin condition usually found on the extremities
- Necrotizing and granulomatous small vessel vasculitis, a condition that includes inflammation and damage to blood vessels in the skin
What to expect with Cutaneous Crohn Disease
The outlook for these skin symptoms closely aligns with the outlook for Crohn’s disease. If skin symptoms are caused by treatment for Crohn’s disease, stopping the anti-TNF medications should lead to their resolution.
Possible Complications When Diagnosed with Cutaneous Crohn Disease
The problems associated with skin symptoms of Crohn’s disease are pretty much the same as those for skin conditions when they aren’t linked with Crohn’s disease.
Preventing Cutaneous Crohn Disease
Crohn’s disease treatment primarily focuses on managing the symptoms rather than completely curing the condition. This means that patients need to stay alert for any changes in their health status and consistently take their prescribed medication. All appointments following the initial diagnosis should prioritize this aspect to ensure effective management of the disease.
