Atopic Dermatitis/Eczema

Question 1

Atopic dermatitis (AD) / eczema

Answer 1

A disorder of altered skin barrier integrity and immune dysregulation that presents as a chronic relapsing inflammatory skin disease.

Question 2

AD: Clinical presentation

Answer 2

• Pruritis with dry, erythematous areas
• Lichenification
• Can manifest with papulovesicular lesions, patches of erythema, exudation, scaling with small vesicles formed within the epidermis.

Question 3

Atopic Triad

Answer 3

30%–50% of cases ― atopic dermatitis, allergic rhinitis, asthma

Question 4

AD Subgroups

Answer 4

Exogenous / extrinsic IgE mediated 70- 80%
Endogenous / intrinsic (non IgE mediated 20-30%).

Question 5

AD: Primary epithelial barrier disruption (endogenous)

Answer 5

• Disruption of tight junctions, permeability of stratum corneum.
• ↑ trans-epidermal water loss.
• Structural protein defects (filaggrin).
• Barrier disruption may be caused by microbial colonisation and release of inflammatory cytokines.

Question 6

AD: Immune
response defect (exogenous)

Answer 6

• Secondary immune dysregulation.
• Defects in TLRs has been implicated in the loss of epidermal innate immunity.
• IgE mediated allergic sensitisation → ↑ susceptibility to allergens, secondary to structural epidermal defects.

Question 7

AD: Causes and risk factors

Answer 7

• Th1/Th2 imbalance
• Stress
• Filaggrin gene mutations
• Nutritional defiencies - D and zinc
• EFA deficiency
• Early life antibiotics
• Associated with ↑ E. coli and Candida albicansin the gut microbiome, and ↓ Bifidobacteria
• H. Pylori
• Excess histamine

Question 8

AD: Laboratory

Answer 8

• Full blood count; serum IgE.
• Allergy and food sensitivity testing
• Comprehensive stool testing.
• Genetic panels