Ch. 12/13-Atopic dermatitis/other eczematous processes Flashcards
(118 cards)
Name 3 cutaneous disseminated viral infections that can occur in the setting of atopic dermatitis
Eczema herpeticum (HSV)
Eczema vaccinatum (Vaccinia)
*Eczema coxsackium (Coxsackie A16; A6; Enterovirus 71; hand-foot-mouth)
What is the atopic march
AD (often food allergy occurs around same time or after)–> Asthma–>allergic rhinitis
What is white dermatographism
Stroking the skin leads to whitening of skin due to vasoconstriction
What are 3 essential features for AD
(Previously Major criteria for Hanifin and Rafka)
Pruritus
Typical morphology in right location
Chronic/relapsing course
Fam hx atopy
Name 23 minor features of AD
White dermatographism
Mid-facial pallor
Delayed blanch response (to intradermal Ach)
Pityriasis alba
Hyperlinear palms /Itchytosis vulgaris
Keratosis pilaris
Perifollicular accentuation
Xerosis
Hertoghe sign
Allergic shiners
Recurrent conjunctivitis
Keratoconus
Anterior sub capsular cataract
Dennie Morgan lines
Anterior neck folds
Hand/foot dermatitis
Nipple eczema
Early onset
Susceptibility to skin infections
Worsened with wools/lipid solvent
Impacted by environment/emotions
Pruritus when sweating
Increased IgE
Food intolerance
Immediate Type 1 skin reactivity
What is needed to make a diagnosis of AD according to HAnifin and Raja
3 major + 3 minor
Name 3 infections that can worsten/flare eczema
Molluscum
Staph
Viral URTI
Hand/foot/mouth
What is prevalence of AD in kids and adults
10-20% kids
2-10% adults
What is early onset AD? Late onset? senile onset?
Early: first 2 years usually, sometimes before age 5
Late: Post puberty
Senil: After 60
What % of kids with AD outgrow it by age 12?
60%
3 major categories of AD pathogenesis
1- Barrier dysfunction
2- Immune dysregulaton
3- Alteration microbiome
What is strongest RF for early onset AD
Fam history-specifically parents-specifically AD > other atopic conditions
What is the strongest known genetic RF for AD
Fillagrin (FLG) loss of function mutation
What is the % of Europeans/Asians with mod-severe AD that carry mutation for FLG
20-50%
What is filagrin?
Keratin filament organizing protein
Found in stratum corneum
Breakdown products such as histidine contribute to epidermal hydration, acid mantle formation, lipid processing, and barrier function
Name 1 genetic mutations increase risk for AD that is not FLG?
SPINK5–> codes for LEKTI= lymphoepithelial Kazaa-type trypsin inhibitor (protease inhibitor, thus loss of function results in increase protease activity)
–> Excessive degradation DSG-1, degradation lipid processing enzymes, activates proinflammastory cytokines
What Th response is seen in acute AD? Chronic AD?
Acute: Th2
Chronic: Th1, Th 17, Th22
What are 2 cytokines drives Th2 response
Il-4
TSLP (thyme stromal lymphopoeitin)-produced by keratinocytes in response to viral infection, trauma, allergens, others. Highly expressed in lesions acute and chronic AD, not-non-lesional.
Describe how IL-4 and Il-13 are related
The heterodimeric receptor for IL-4 and IL-13 both share the IL4alpha receptor subunit, which activates STAT-6–> promoted th2 differentiation
Dupixent is a IL4alpha receptor blocker, thus blocks IL-13 and IL-4
What is IL-31
Th2 cytokine highly expressed in AD and pruritic skin conditions such as PN
Cutaneous exposure to staph rapidly induces Il-31 production, role for staph colonization and itch induction
It is expressed in keratinocytes, nerve fibres, dorsal root ganglion
What is the name of the IL-31 inhibitor
Nemolizumab
What % of AD patients are colonized with staph aureus? Why?
90%
Due to disrupted acid mantle, decreased antimicrobial peptides
Most common sites AD infantile
Cheeks, forehead, scalp, neck, extensors, trunk
Spares central face (but 90% have face involvement)
Often spares axillae/groin
What is frictional lichenoid eruption
Skin coloured flat topped papules often elbows > knees, often atopic boys in spring/summer