Manifestations cutanées de la maladie de Crohn (Pour les professionnels)

• Inflammatory bowel disease (IBD) may manifest itself in the skin. One such IBD is Crohn’s disease. This IBD affects the gut anywhere from the mouth to the anus and results to gut obstruction and painful diarrhea. There may also be fever, constipation, weight loss, and painful joints due to inflammation brought about by triggers. However, the skin manifestations often appear earlier than any other involvement of the other body organs or systems.
• In 40% of patients with Crohn’s disease, there are visible changes in the skin, especially in areas near the anal area. The skin in the anal area may have abscesses and fissures or skin cracks. These skin abscesses and cracks may get infected and may have dangerous consequences such as the spread of infection to other parts of the body through the blood, a life-threatening condition known as sepsis. It is not only in the anal area that breaks in the skin occur; there may also be ulcers in the vulva of the female or the scrotum of the male.
• In 8 to 10% of the people with Crohn’s disease, the mouth area may be involved. The gums may swell as well as the mucosal area of the mouth. The mucosa of the mouth may also be seen with whitish plaques with cobblestone appearance. There may also be mouth sores and skin tags along with mouth ulcers and reddish, tender inflammation of the mouth surface.
• Other skin manifestations of Crohn’s disease include:

1. pyoderma gangrenosum
2. erythema multiforme
3. erythema nodosum
4. pyodermatitis- pyostomatitis vegetans
5. necrotizing small vessel vasculitis.

Let us discuss each of these one by one.

• Pyoderma gangrenosum is a form of ulceration which commonly presents itself as reddish sores in the lower legs. It may start as a small bump, blister or pustule which later on results to a break in the skin, creating an ulcer (which borders are typically undermined). This ulcer may be deep and may expose reddish surfaces of the skin and have purplish borders as it enlarges. Typically other areas transform into ulcers when pricked with a needle (pathergy sign). The ulcer is very painful and if treated, will take months to heal. The scars soon appear with crisscross patterns.
• Erythema nodosum are skin lesions with accompanying fever as a symptom. They appear as red lumps in the knees and legs, which may resemble cherries or grapefruits. They usually number between 2-50 lumps on the front and sides of the legs and knees, although it may also involve the thighs, outer arms, face and neck. They then develop into raised oval patches which are warm, painful and reddish and later on become purplish in about 10 days up to several weeks. There may also be diffuse pain and swelling in the legs.
• Erythema multiforme appears as reddish or pinkish round marks (or macules) which may become raised as papules and then enlarge to form plaques. The center then becomes darker in color and may develop blisters. The changes into these target-like lesions may take place during 72 hours and may appear in the back of the hands, tops of feet and may later on spread to the limbs, elbows, knees, truck, neck and face.
• Pyodermatitis-pyostomatitis vegetans appears as pus-filled bumps and rashes in the skin folds of the armpits, groins and scalp. The skin over it is reddish or brown, with crusts; The mouth may also have red ulcers with pus.
• Necrotizing small vessel vasculitis is an inflammation of the blood vessels which may manifest as purplish bruises or purpura and smaller petechiae, because of bleeding of small blood vessels below the skin.

So, how would you know if you are dealing with skin manifestations of Crohn’s disease?

• See your doctor, who may then request skin biopsy for you. A very small part of the skin is taken and examined under a microscope for the presence of non-caseating granulomas, which are characteristic appearances in the skin of those with Crohn’s disease.
• If your doctor sees this result, he may then refer you for a gastrointestinal work-up as a suspect for Crohn’s disease.
• When treating skin disorders related to Crohn’s disease, one should know that the skin disease cannot be entirely cured and that the treatment is symptomatic. Medicines include oral steroids and anti-inflammatory drugs such as azathioprine, sulfasalazine and infliximab.

Contributors:

Dr Christophe HSU – dermatologist. Geneva, Switzerland