Atopic Dermatitis Flashcards
What is atopic dermatitis
Chronic relapsing skin disorder with intense itch
Usually associated with family history of atopic disease
-atopic march (AD, asthma, rhinitis)
Describe the epidemiology of AD
Generally found in childhood
-most within 1st year of life, 1 to 5
Rarely occurs for the 1st time during adulthood
Prevalence increasing
What 3 factors contribute to the aetiology of AD
Environmental
- allergens, irritants, dietary factors
- infections, stress
- pollutants, weather change
Genetic
- FHx, genetic disposition
- defective skin barrier
- abnormal Th2, IgE immune response
Describe how gene mutations contribute to barrier dysfunction
-how common is this mutation
Normal functioning of filaggrin
- converted from profilaggrin between the stratum granulosum and corneum
- in corneum => incooporated into lipid envelope for skin barrier function
- releases AA that aid in water retention
Abnormal functioning
- abnormal barrier => increased AG entry, Th2 response
- increased dryness
10% of us have the mutation
40% of mutation carriers have eczema
-more likely to have atopic triad
Describe the pathophysiology behind AD
Impaired stratum corneum barrier function
- decreased functional filaggrin =>
- increased protease => corneocyte dysadhesion
- abnormal lipids => increased SC permeability
Environmental factors
- altered skin microbiome (more S aureus)
- damage to epidermal barrier and increased skin barrier penetration of AG => immune activation
Both contribute to immune dysregulation
-keratinocyte derived pro Th2, ILC cytokines => acute innate, adaptive and chronic responses
Describe the presentation of AD in different age group[s
- infant
- child
- adults
Infant => forehead, cheeks, extensor surfaces
-papules, vesicles that crust
Child => flexor surfaces, face, neck
Adult => hands, neck, shoulders, flexor surfaces
May also have
- periorbital eczema
- xerosis (general dryness)
- excoriations and prurigo (due to intense itch)
- impetiginization
If chronic
-lichenification (increased skin markings)
Describe the prognosis of AD
Chronic disease with recurrent flares
- most children outgrow it
- adults may continue to have localised dermatitis on hands
Frequent skin infections, S aureus colonization
-eczema herpeticum <= herpes virus
Describe the comorbidities that accommpany AD
Obesity, smoking => increased risk for AD
Atopic
- atopic triad
- allergic conjunctivitis, rhinosinusitis, esophagitis
- allergy contact dermatitis
Infection (cutaneous, extracutaneous)
AI
Skin pain and itch
Sleep disturbances
Neuropsych
- anxiety, depression, suicide
- ADHD
How would you treat AD
- topical
- systemic
Topical
- Emollients
- CS
- calcineurin inh (inhibits Tcell activation)
- antiseptic wash (for frequent infections)
Systemic
- short course prednisolone
- phototherapy
- methotrexate, ciclosporin, azothiopurine
- mycophenolate mofetil
- biologics
What is dulipumab
- how does it work
- what are the side effects
IL4, 13 inh
Normally IL4 => Th2 activation
- produces IL4, IL5, IL13, IL31 => activates eosinophils, basophils, mast cells, IgE releasing B cells, T cells
- +ve feedback loop of IL4
- leads to weakening of epidermal barrier, reduction in antimicrobial peptides
Conjunctivitis
Enthesitis, arthritis
When would you use dulipumab
Only recommended in
- moderate/severe AD in adults if
- no response/contraindicated/not tolerant to at least 1 other systemic therapy
Stop dupilumab at 4 months if no response
