Eczema Flashcards
Contact dermatitis can be what two things?
- irritant (MC): acute or chronic inflammation of the dermis/epidermis as a result of direct irritation to the skin
- allergic: delayed type hypersensitivity rxn to contact allergen
RFs to contact dermatitis
- frequent handwashing or water immersion
- atopic dermatitis (d/t barrier dysfunction)
- genetics
- environment
- increased exposure to allergens
patho of irritant contact dermatitis
- no immune response
- can occur w/ first exposure
- disruption of epidermal barrier by chemicals or physical irritants –> damage to cell membrane –> cytotoxic effect on skin cells
patho of allergic contact dermatitis
- requires an initial exposure and sensitiziation to allergen
- only occurs in susceptible individuals
- repeat exposure leads to type IV hypersensitivity rxn
common causes of irritant contact dermatitis
- hand washing
- soaps
- saliva
- urine/feces
- high concentrations of most chemicals
common causes of allergic contact dermatitis
- nickel and other metals
- hair products
- solvents (toluene)
- additives to meds and cosmetics
- rubber
- fragrances (balsam of Peru)
- clothing dyes
- formaldehydes
- topical abx
- plants
what is a major topical antibiotic that causes allergic contact derm?
NEOMYCIN!
timing of the development of both types of contact dermatitis
- irritant: immediately
- allergic: 48-72 hrs or longer after exposure
hx in contact dermatitis
- when
- where
- shape
- size
- itchy or not
- burn or painful
- warmth
- used anything to tx
- better or worse
- child have it?
PE in contact derm
- acute: mild skin dryness and erythema to eczematous papules and patches, edema, vesicles, and oozing
- chronic: lichenification, erythema, hyperkeratosis, cracking, scaling
what test distinguishes irritant and allergic contact derm?
epicutaneous patch testing
Ddx in contact dermatitis
- urticaria
- atopic dermatitis
- drug eruption
- nummular eczema
- bullous pemphigoid
- virus
diaper dermatitis
- erythematous, scaly, eroded painful lesions w/ sparing of the creases***
- in candida dermatitis: bright BEEFY red in creases w/ satellite lesions
atopic dermatitis
- chronic, relapsing pruritic eczematous condition affecting characteristic sites
- MC begins in infancy or early childhood
- usually fam hx of atopy (asthma, rhinitis)
RFs for atopic dermatitis
- genetic predisoposition
- mutation in the filaggrin gene
- “itch-scratch cycle”
- associated w/ food sensitivities, hyper-IgE syndrome, IL-31 upregulation
pathophys of atopic derm
- immune dysregulation w/ increase T cell activation and cytokine production, leading to increased IgE production
- intercellular edema that can lead to vesicle formation
- mutations in filagrin gene –> abnl skin barrier fxn and increased water loss and increased penetration of allergens
PE in atopic dermatitis
- erythematous and scaly maculopapular exudateive patches
- chronic: hyperpigmentation or hypopigmentation, lichenification and scaling
what is the presentation of atopic derm in infancy?
- widespread
- primarily affecting extensor surfaces
- also involves cheeks, forehead, scalp
what is the presentation of atopic derm in childhood?
- characteristic flexural sites w/ lichenification
- hands and face can also be involved
- from adolescence to adulthood, the flexures, neck, hands, and feet are primarily involved
how can severe atopic dermatitis present?
exfoliative erythroderma w/ diffuse scaling and erythema
other associated findings w/ atopic dermatitis
- Dennie-Morgan fold (infraorbital folds)
- dry white patches
- hyperlinear palms
- facial pallor
- infraorbital darkening
- follicular accentuation
- keratosis pilaris
- ichthyolsis
