Atopic Dermatitis

Atopic Dermatitis (AD), also known as atopic eczema, is a chronic inflammatory skin condition characterised by itchy, red, swollen, and cracked skin.

It can present clear fluid oozing from affected areas, which may thicken over time. AD affects approximately 20% of people at some point in their lives, predominantly impacting younger children, with females being slightly more affected than males. Although many outgrow the condition, it typically begins in childhood and exhibits varying severity throughout life.

Commonly affected areas in children include the face, limbs, knees, elbows, and neck, while adults often experience symptoms on the hands and feet. Scratching exacerbates the condition and increases the risk of skin infections, hay fever, and asthma.

Signs and Symptoms

The primary symptom of AD is intense itching, which can lead to burning, soreness, or pain. Affected individuals often have generally dry skin, which appears greyish in darker skin tones and inflamed in lighter skin. Visible changes include scaling, cracking, swelling, scratch marks, bumpiness, fluid oozing, and skin thickening in chronic cases. AD commonly affects the eyelids, forming extra creases known as Dennie-Morgan infraorbital folds, and can cause painful cracks under the ears.

Causes

The exact cause of AD is unknown, but it likely involves genetic, immunologic, and environmental factors. Risk factors include a family history of atopy, urban living, dry climates, and exposure to certain chemicals. The condition is not contagious.

Pollution and Climate

Since 1970, the incidence of AD has increased significantly, particularly in urban areas. Chemicals like (di)isocyanates and xylene may contribute to skin barrier dysfunction and increased risk of AD. Low humidity and temperature also exacerbate AD symptoms.

Genetics and Hygiene Hypothesis

Many individuals with AD have a family history of atopy, producing substantial amounts of IgE and are prone to asthma, hay fever, and other allergic conditions. Mutations in the filaggrin gene (FLG) are linked to early-onset AD and asthma. The hygiene hypothesis suggests that limited exposure to microorganisms in early childhood leads to an underdeveloped immune system and increased allergy risk.

Allergens and Staphylococcus aureus

Exposure to allergens, like dust mites and certain foods, can worsen AD. Staphylococcus aureus colonisation is prevalent in AD patients, exacerbating the condition. However, AD is non-communicable, and anti-staphylococcal treatments are not consistently effective.

Diagnosis

AD is typically diagnosed based on clinical signs and symptoms, with several validated criteria aiding diagnosis. The UK Diagnostic Criteria involves itchy skin plus three or more additional factors such as flexural dermatitis, history of asthma or allergic rhinitis, early symptom onset, history of dry skin, and visible dermatitis.

Treatments

While no cure exists, treatments aim to reduce flare severity and frequency. Topical corticosteroids and moisturisers are commonly used. Phototherapy, systemic immunosuppressants, and monoclonal antibodies may be indicated for more severe cases.

Moisturisers

Daily use of moisturisers helps stabilise the skin barrier and reduce AD symptoms. They can be applied as leave-on treatments, bath additives, or soap substitutes, with various formulations available.

Medication

Topical corticosteroids and calcineurin inhibitors like tacrolimus and pimecrolimus are effective in managing AD flare-ups. Systemic treatments include immunosuppressants, monoclonal antibodies, and JAK inhibitors.

Diet and Lifestyle

Vitamin D supplementation and probiotics may benefit AD patients, while dietary exclusions are only recommended if food allergies are suspected. Regular bathing, avoiding wool, and using written action plans for treatment regimens can support self-management.

Light Therapy

Narrowband UVB phototherapy can help reduce AD severity and itching, though it carries a risk of skin cancer with prolonged use.

Burden of Disease

AD significantly impairs quality of life, leading to psychological issues like depression and anxiety, sleep disturbances, and reduced productivity. The economic burden is substantial, with high direct and indirect costs.

---

Self-assessment MCQs (single best answer)

Which of the following is NOT a common symptom of Atopic Dermatitis (AD)?

Atopic Dermatitis is primarily characterised by which of the following?

Which gene mutation is commonly associated with early-onset AD?

What percentage of people are affected by AD at some point in their lives?

Which of the following treatments is NOT commonly used for Atopic Dermatitis?

In which demographic is Atopic Dermatitis more common?

Which of the following environmental factors can exacerbate AD symptoms?

What does the "hygiene hypothesis" suggest about the development of AD?

Which microorganism is known to colonise the skin of AD patients and exacerbate the condition?

Which of the following is a part of the UK Diagnostic Criteria for AD?