Eczema (Atopic Dermatitis) | Atopic Triad, Triggers, Who gets it, Why does it happen, & Treatment

Summary

This lesson delves into atopic dermatitis, also known as eczema, a chronic autoimmune inflammatory skin condition affecting 5-20% of children worldwide. It often manifests in skin creases and is linked to the atopic triad: atopic dermatitis, allergic rhinitis, and asthma. The condition can be triggered by a defective epidermal barrier and immune dysregulation. Risk factors include family history and environmental factors, while early exposure to daycare and pets may be protective. Diagnosis is clinical, with specific criteria for a more objective approach. Treatment involves avoiding triggers, using topical corticosteroids, calcineurin inhibitors, phototherapy, and possibly melatonin for symptom relief.

Takeaways

• 🌐 Atopic dermatitis, also known as eczema, is a chronic, autoimmune, pruritic, and inflammatory skin condition.
• 👶 It is prevalent in approximately 5-20% of children worldwide and often begins in childhood.
• 🔗 Atopic dermatitis is associated with the atopic triad: atopic dermatitis, allergic rhinitis, and asthma.
• 🧬 The condition can be linked to genetic factors, including a mutation in the filaggrin gene.
• 🚫 Environmental factors like hard water can exacerbate symptoms.
• 🛡 Protective factors include early daycare attendance, pet exposure, and exposure to farm animals, which may reduce the risk.
• 👨‍⚕️ The diagnosis is typically clinical, based on the presence of pruritic skin lesions in flexural surfaces and associated atopic stigmata.
• 💊 Treatment involves avoiding triggers and allergens, and may include topical corticosteroids, calcineurin inhibitors, phototherapy, and cyclosporine for severe cases.
• 🧴 Topical calcineurin inhibitors are preferred for sensitive areas like the face to prevent skin thinning.
• 🛌 Antihistamines can help with pruritus, and melatonin might offer some relief, though more research is needed.

Q & A

What is atopic dermatitis, and what are its key characteristics?

Atopic dermatitis, also known as eczema, is a chronic autoimmune inflammatory skin condition. It is characterized by itching (pruritus), inflammation, and a tendency to affect skin creases and flexure surfaces. It typically begins in childhood and affects about 5-20% of children worldwide.

What is the atopic triad, and how is it related to atopic dermatitis?

The atopic triad refers to the association between atopic dermatitis, allergic rhinitis, and asthma. These conditions are linked to elevated levels of immunoglobulin E (IgE), and approximately 80% of individuals with atopic dermatitis will develop either allergic rhinitis, asthma, or both.

What are the two main categories of pathogenesis for atopic dermatitis?

The pathogenesis of atopic dermatitis involves two main categories: (1) a defective epidermal barrier due to issues such as filaggrin deficiency and tight junction abnormalities, and (2) immune dysregulation, involving both the innate immune system (reduced TLR-2 and TLR-9 function) and the adaptive immune system (increased expression of Th2, Th17, and Th22 cytokines).

What are some risk factors for developing atopic dermatitis?

Risk factors include a family history of atopic dermatitis or allergies, genetic mutations (such as filaggrin gene mutation), having allergies, and exposure to environmental factors like water hardness. Family history is a major factor, with about 70% of individuals with atopic dermatitis having a positive family history.

What are some protective factors against atopic dermatitis?

Protective factors include early exposure to daycare, pets, and farm animals, which may reduce the risk of developing atopic dermatitis. This aligns with the hygiene hypothesis, which suggests that exposure to diverse germs and allergens can help the immune system regulate itself more effectively.

What are some common skin findings associated with atopic dermatitis?

Common skin findings include keratosis pilaris (chicken skin), Denny-Morgan folds (wrinkling under the eyes), Hertoghe’s sign (thinning of the lateral eyebrows), pityriasis alba (whitening of the skin), palmar hyperlinearity (increased skin lines on the palms), and retroauricular fissures (chafing behind the ears).

How is atopic dermatitis diagnosed?

Atopic dermatitis is generally diagnosed clinically, based on characteristic symptoms such as itchy skin lesions in flexural surfaces, dry skin, and a history of asthma or hay fever. Alternatively, the UK Working Group's diagnostic criteria can be used, requiring pruritus and at least three other features like skin creases, early onset, or a family history of atopic conditions.

What are the common triggers of atopic dermatitis flare-ups?

Common triggers include environmental factors such as heat and low humidity, stress, and certain foods. There is debate among clinicians about whether foods like dairy worsen atopic dermatitis, so elimination diets may be considered on a case-by-case basis.

What are some treatments available for atopic dermatitis?

Treatment options include avoiding triggers, using topical corticosteroids (e.g., hydrocortisone cream), topical calcineurin inhibitors (for sensitive areas like the face and eyelids), phototherapy for severe cases, and cyclosporine for acute flare-ups. Antihistamines can help with itching, and melatonin may be considered to aid with symptoms, though more research is needed.

Why are topical calcineurin inhibitors used for atopic dermatitis on certain body areas?

Topical calcineurin inhibitors are used for areas like the face, eyelids, neck, and skin folds because prolonged use of corticosteroids in these regions can lead to skin thinning. Calcineurin inhibitors avoid this side effect while providing effective treatment.