What is it?

Atopic dermatitis is a very common skin problem seen mostly in children; up to 15-20% of children are estimated to have it. Atopic dermatitis patients have higher than normal rates of asthma and allergies and may have family members who have asthma, allergies or atopic dermatitis. Atopic dermatitis is often called eczema and causes itchy red areas to appear on the skin. It is caused by a complex interaction between the environment, skin and immune system. It tends to come and go and sometimes will be itchy even before the rash is seen. Most patients with atopic dermatitis present as young children and many improve with time. Some continue to have severe skin problems into adulthood.

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What does it look like?

In young children, it is most common on the face, elbows and knees but can be anywhere. It tends to spare the diaper area. In older children and adults, it often goes to the bend of the elbow (antecubital fossae) or the creases behind the knee (popliteal fossae). Palmoplantar skin and eyelid dermatitis are areas often involved in older children. Patients with atopic dermatitis often have very dry skin, and their skin can still look dry even if they apply moisturizer several times a day. Often the skin around the hair follicles is a bit noticeable, usually because it’s slightly raised and hypopigmented (follicular prominence). Areas affected by the eczema might become lighter or darker (post-inflammatory hypo- and hyper-pigmentation). 

What makes it worse?

Certain triggers such as fragrance and harsh soaps can make the rash worse and should be avoided. Each person with atopic dermatitis are at increased risk of food allergy, but atopic dermatitis is not caused by food allergy, though certain foods might make it flare. In particular, food such as tomato products can cause worsening on the face, primarily due to contact with the food. In general, food avoidance/elimination is not recommended and should be discussed with an allergist to avoid unnecessary complications including the risk of malnutrition or anaphylaxis upon re-exposure. 

How is it treated?

There is no cure for atopic dermatitis, but treatment can improve the symptoms, while maintenance therapy and a good daily skin care routine can help prevent flares.

• Daily bath with warm, not hot water and soap limited to areas such as hands, feet, axillae, and groin. Apply moisturizer immediately after the bath.
• Topical medications (see below) can be applied twice daily to affected areas until clear. Sometimes this might require using medicine on all of the skin for a short period of time. Maintenance therapy of twice weekly application is helpful to prevent flares. Oral antihistamines are not particularly effective in controlling the itch associated with atopic dermatitis. Some are sedating and can be used in extreme flares as a sleep aid, but melatonin is likely a safer alternative.

Systemic Treatments: When not responsive to topical therapy, systemic treatment might be needed.

• Phototherapy – Narrow band UVB, usually 2-3 times per week.
• Systemic immunomodulators such as methotrexate, cyclosporine, MMF, IL4/IL13 blockers (dupilumab, tralokinumab), or JAK inhibitor (upadacitinib, abrocitinib) may be necessary.

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Complications?

Complications of atopic dermatitis include loss of sleep, distractibility during the day due to itch, stress due to chronic relapsing and remitting nature of the condition, and infection.

Infection:  Staphylococcus aureus is the most common pathogen, but Streptococcus pyogenes can be seen as well. Secondarily infected plaques have a yellow honey-coloured crust on top and may lead to widespread worsening of the eczema. Secondary infections are usually treated with systemic antibiotics such as cephalexin. A culture with sensitivities can direct proper antibiotic therapy if there is concern for MRSA. Dilute bleach baths, using ¼ cup bleach per tub of water for a 10 min soak 2-3 times per week, might be helpful and has both antimicrobial and anti-inflammatory benefits. Eczema herpeticum is the explosive development of blisters due to herpes simplex virus (that otherwise causes cold sores) in patients with atopic dermatitis. This eruption can be quite severe and must be treated aggressively acyclovir. Eczema coxsackium is a similar condition and morphologically can be confused with eczema herpeticum, caused by coxsackie virus and only requires supportive therapy and treatment of the underlying eczema. Lesions on hands, feet, and on oral mucosa aids in diagnosis.