Atopic Dermatitis

28 May

The most common form of eczema is a chronic skin disorder, which can be stimulated by factors such as environmental triggers, genetics and immune mechanisms.

- 1 in 10 Americans have atopic dermatitis
- African/ Asian Americans are more likely to develop Atopic Dermatitis than white children [1]
- Affects 11-20% of children and 5-15% of adults in the United Kingdom [2,3]
- The prevalence of atopic dermatitis affects up to 20% of children and 10% of adults
- The burden of disease ranks 15th worldwide for non-fatal diseases
- Ranked number 1 in skin diseases measured in Disability Adjusted Life Years [3]
- Irritants such as soaps, detergents, washing liquids, bubble bath
- Environmental factors such as cold/ dry weather, mould, dust and fur
- Food allergies
- Certain materials like wool and synthetic fabrics
- Skin infections
- Insect bites
- Hormonal changes eg. before periods or during pregnancy [7]
Medical Student
Epidermal dysfunction
- The interleukins 4,13,31 and 33 reduce the production of epidermal barrier proteins.
- This includes filaggrin protein, keratins and other molecules.
- The effects of this epithelial skin dysfunction reduced skin hydration, increases skin pH, increases penetration of allergens, increased pro-inflammatory cytokines and reduced inflammatory threshold levels. [4]
Neuroimmunological mechanisms
- The damage to neuro-immune systems plays an important role in the pathophysiology of Atopic Dermatitis.
- Sensory nerve endings also release neuro-mediators into the skin- this stimulates the triage of inflammation, barrier defects and puritis [5]
Immune dysregulation
- T-cell–mediated delayed-type hypersensitivity and includes a Th2-dominant component in the skin.
- Immune cytokines like Interleukin 4 and 13 contribute to chemokine production, skin barrier dysfunction, allergic inflammation and the suppression of antimicrobial peptides.
- The increased penetration of skin irritants and allergens also results in a Th2-dominant inflammation, which also drives IgE production and predisposes to immediate-type hypersensitivities. [4,6]
Genetics
- The filaggrin gene which encodes the filaggrin protein, is a major component in structuring the outer layer of the epidermis (stratum corneum).
- A mutation in this gene causes degradation products and contributes to impaired skin barrier functions (increasing the risk of Atopic Dermatitis)
- The T helper type 2 signalling pathway is altered; causing an up-regulation of interleukins 4 and 13. Reducing gene expression, which leads to skin barrier defects. Contributing to the development of Atopic Dermatitis. [6]
Patients
Genetics
- The existence of genetic mutation in a gene specific to the skin barrier is defective
- Increases the risk of severe atopic dermatitis and higher IgE levels
Environmental factors
- Irritants, tobacco smoke, pollen, dust mites, pet fur, mould, and certain materials like wool and synthetic fabrics
Defective skin barriers
- Genetic mutations cause skin irritation and the development of dry skin and membranes
Mechanisms of the Immune System
- Atopic dermatitis is a cell-controlled reaction which increases the risk of developing bacterial and viral skin infections.
- The increase in environmental factors also stimulated specific protein production and immune response. [6,7]
- Weakened immune system
- Family/personal history of hay fever or asthma
- Dry skin
- Filaggrin gene mutations
- Stress
- Female sex
- Damp hands and feet
- Environmental exposure to irritants [8]
- Redness and blisters
- Weeping or crusted skin
- Over time can become less red and thickened
- Greyish/white patches on darker skin
- Cracking of the skin
- Can be found on the flexor aspects of the body, as well as the hands, eyes or neck.
- In patients of African descent, perifollicular (around the follicle) and extensor areas are more commonly affected.
- After an inflammatory episode, hypo/hyper-pigmentation is more likely to occur in skin of colour than white skin. [6]
- Severity grading:
  - Clear – Normal skin
  - Mild – Dry skin, infrequent itching, slight redness/purple/dark-red
  - Moderate – Dry skin, frequent itching, more marked redness
- Scoring tools:
  - Visual analogue scales (0–10): severity, itch, and sleep loss over the past 3 days/nights
  - POEM (Patient-Oriented Eczema Measure)
- Assess psychological impact – screen for reduced quality of life and distress
- Identify allergens or irritants specific to the patient
- Referal to a dermatologist may be needed
- Patch test
  - Potentially triggering substances are attached to an area of the body using tape
  - Can be attached to places like the upper arm, the back or the forearm.
  - 2 days later, the patches are removed and assessed to note any reactions.
  - Can be accessed 2 days post initial investigation as atopic dermatitis reactions can appear later. [7]
- Seborrheic dermatitis
- Contact dermatitis
- Lichen simplex
- Psoriasis
- Scabies
- Impetigo
- Zinc deficiency
- Hyper IgE syndrome
- Candidiasis [9]
Medical Students
- Grade severity:
  - Clear: Normal skin
  - Mild: Dry skin, infrequent itch
  - Moderate: Frequent itch, red/purple areas
- Use Visual Analogue Scale (0–10) and POEM score
- Assess psychological impact (QoL, distress)
Mild AD
- Emollients
- Mild steroid: Hydrocortisone 1% (after 48h of flare control)
- Educate on self-care & flare prevention
- Refer to dermatology or psychology if needed
Moderate AD
- Identify triggers or infection
- Emollients
- Moderate steroids:
  - Betamethasone 0.025%
  - Clobetasone 0.05%
- Use Hydrocortisone on delicate areas
- Add non-sedating antihistamines for itch (e.g. cetirizine)
- Consider calcineurin inhibitors (e.g. tacrolimus)
- Refer if uncontrolled or psychological distress
- Refer to specialists if food allergy suspected
Severe AD
- Consider admission if eczema herpeticum
- Potent steroids (e.g. Betamethasone 0.1%)
- Moderate steroids on delicate skin
- Use sedating antihistamines if sleep is affected
- Short course of oral steroids in severe distress
- Urgent referral if not improved in 1 week
- Address psychological and allergy concerns
Patients
Mild AD
- Use moisturisers (emollients) regularly
- Apply mild steroid cream (e.g. Hydrocortisone) only as advised
- Learn how to avoid triggers and care for your skin
Moderate AD
- Moisturise often
- Use stronger creams as prescribed (e.g. Betamethasone or Clobetasone)
- Avoid known triggers (e.g. soaps, allergens)
- You may be given allergy tablets (antihistamines) to reduce itching
- See your doctor if symptoms continue or affect your wellbeing
- May be referred if a food allergy is suspected
Severe AD
- Seek help urgently if skin is badly infected or painful
- Strong steroid creams may be needed (but used with care)
- Allergy or sleep tablets may help with itching
- You may be offered a short course of oral steroids
- You should be referred to a skin doctor (dermatologist) if it's not improving
- Support from a psychologist may help if it affects mental health
- Bacterial skin infections
- Viral skin infections (herpes simplex virus)
- Eczema herpeticum
- Psychological effects such as bullying, problems sleeping, self-image/ confidence [7]
- Only children get eczema
- Itchy skin isn’t a red flag
- It will self resolve
- Treatment will cure/eradicate eczema
- Lifestyle changes won’t singularly help eczema
- Atopic dermatitis is contagious
- Atopic dermatitis is caused by stress [11,12]
- What can I do to manage my symptoms?
- Are there any products that can make my eczema worse?
- Are there ways I can treat my skin to reduce my chances of another flare-up?
- What should I do if the medication doesn’t work?
- When should I apply/use my medication?
- The British Association of Dermatologists
- The National Eczema Society
- Eczema Care Online
[1] https://www.aad.org/public/diseases/eczema/types/atopic-dermatitis
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7573657/#:~:text=The
[3] https://www.eczemacouncil.org/assets/docs/global-report-on-atopic-dermatitis-2022.pd
[4] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6399565/
[5] https://www.sciencedirect.com/science/article/pii/S0091674922003803
[6] https://www.msdmanuals.com/en-gb/professional/dermatologic-disorders/dermatitis/atopic-dermatitis-eczema
[7] https://www.nhs.uk/conditions/atopic-eczema/causes/#:~:text=environmental
[8] https://atopicdermatitis.net/eczema-risk-factors
[9] https://www.researchgate.net/figure/Differential-diagnosis-of-atopic-dermatitis-1-4-19_fig3_318529114
[10] https://cks.nice.org.uk/topics/eczema-atopic/management/severe-eczema/
[11] https://www.everydayhealth.com/eczema/eczema-myths-debunked/
[12]https://www.dermatologynwhouston.com/5-common-myths-about-eczema/