An Introduction to Atopic Dermatitis
Atopic dermatitis, also known as eczema, is the most common type of dermatitis. Dermatitis is a group of conditions characterized by inflammation of the skin, but today we are just going to dive into atopic dermatitis.
First, we have to understand what dermatitis actually means as a word, before we can begin to understand it as a medical term. Let’s break down the word:
DERMA- is a combining form that means the skin ITIS- is a suffix that means inflammation
Atopic dermatitis is a chronic, autoimmune skin inflammatory resulting in a dry itchy rash in various areas of the body that are common among infants, many of whom outgrow it before adulthood but some cases last for years.
It falls into a category of diseases called atopic, meaning allergic reactions. More specifically, the immune system attacks the skin causing a dry, itchy, and scaly rash on flexor surfaces of the body areas like the creases of the wrist, the insides of the elbows, and the backs of the knees as well as exposed skin surfaces like on the face, the hands, and the feet.
It’s estimated that AD affects 35 million Americans: 1-3% of adults, and 10-20% of children. Seventy percent of cases start in children younger than 5 years old, and about 60% of infants who have eczema continue to have one or more symptoms in adulthood.
Healthy skin helps retain moisture and protects one from bacteria, irritants, and allergens, however, due to a combination of genetics, abnormal function of the immune system, the environment, and defective epidermal barrier, AD patients have dry skin with a dysfunctional skin barrier. Therefore, it is easier for bacteria and allergens to get into the skin through pores, this will stimulate a series of immune responses to attack the allergens that will cause blood to dilate and inflammation on the skin, resulting in dry and itchy skin.
In regards to AD, often cases present Filaggrin deficiency, a structural protein that is essential for the skin barrier function of the stratum corneum (the outer layer of the epidermis). In this case, scratching the itchy rash further damages the epidermal barrier since it increases transepidermal water loss and dermal penetration by allergens and microbes, leading to innate and acquired immune responses including the proliferation of the Th2, Th17, and Th22 subset of helper T cells, which are thought to be major drivers of disease-related inflammation.
Symptoms of atopic dermatitis vary from person to person but include patches of chronically itchy, dry, thickened skin. The itch is usually more severe at night due to little movement that might affect the child’s sleep quality. If scratched, dry patches of skin and open sores with crusts may develop and get infected. Furthermore, there will be small, raised bumps and thickened skin. Children with AD will present red skin patches on various parts of their body but these patches aren’t contagious so it’s safe to interact with others. The appearance of the skin affected by AD will depend on how much a person scratches it, it’s strongly recommended to not scratch the patches as it will further irritate the skin, increase inflammation, and make the itch worse. Common triggers such as pollen, soaps and cleansers, perfume fragrance, cosmetics, dust and sand, chlorine, cigarette smoke, alcohol, pet dander, synthetic fibers, temperature, and stress can also worsen the symptoms.
Although the reason is not known AD is commonly associated with other conditions called the atopic triad. All these conditions start with the letter “A” and they all have an association with increased levels of immunoglobulin E. The atopic triad includes atopic dermatitis, allergic rhinitis (hay fever), and atopic asthma. It’s been estimated that approximately 80% of individuals with atopic dermatitis will develop either allergic rhinitis or atopic asthma or both! Another condition associated with atopic dermatitis to keep in mind are allergic reactions: atopic dermatitis patients have a predilection for having food-induced allergic reactions like eggs, milk, and peanuts.
Unfortunately, there’s no cure for atopic dermatitis, current treatments revolve on breaking the cycle of AD (allergy-mediated inflammation >> dry skin >> itching). The best course of treatment is to identify and avoid the common triggers specific to the patient. If AD acts up when the patient wears polyester, try changing their clothing into soft fabrics like cotton, silk, rayon, and linen. To combat dry skin, frequent moisturization is recommended after warm baths every day. Medications vary since the severity is different for each person: common creams such as hydrocortisone and corticosteroid help mild eczema control itching and help repair the skin. Your doctor may prescribe an antibiotic cream if your skin has a bacterial infection, an open sore, or cracks. He or she may recommend taking oral antibiotics for a short time to treat an infection. Antihistamines are also prescribed by reducing the number of histamines produced when allergic reactions occur. For more severe cases of AD for patients 12 and older, doctors will prescribe dupilumab (dupixent), an injectable medicine, to control the body’s inflammatory response.
Graphics by Haasira
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