Lecture 6: Dermatitis and Eczema Flashcards
What is the triad of atopy?
- Atopic dermatitis
- Allergic rhinitis/hay fever
- Asthma
What is the underlying mediating physiology for atopic dermatitis?
IgE mediation
Where does atopic dermatitis MC occur?
- Face/scalp/torso/extensors
- Flexures
What is the cycle of atopic dermatitis?
- Dry skin
- Pruritis
- Increased inflammation
- Lichenification
Why does skin get dehydrated in atopic dermatitis?
- Impaired filagrin production
- Reduced ceramide levels
- Increased trans-epidermal water loss
What ILs tend to be expressed in atopic dermatitis?
- IL-4
- IL-13
What are the 3 types of atopic dermatitis?
- Acute: erythema/vesicles/bullae/weeping/crusting
- Subacute: scaly plaques/papules/round erosions/crusts
- Chronic eczema: lichenification/scaling/hyper/hypo-pigmentation (itch that rashes)
Hallmark sign of atopic dermatitis
Intense pruritis
Leading to lichenification as you keep scratching
What should we be worried about in atopic dermatitis as they continue scratching?
Secondary impetiginization via staph/HSV/coxsackie/vaccinia
Breaking skin = prone to infection
What features suggest someone has atopic dermatitis?
- Chronic: periorbital plaques
- Hyperpigmentation
- Hyperlinear palms
- Keratosis pilaris
- Hx of allergies
What is the primary thing that clues you into atopic dermatitis?
Hx and FHx
What is the tx for atopic dermatitis?
- Gentle cleansers
- Low strength steroids
How do you manage striae in atopic dermatitis?
- Ointment without preservatives
- Damp skin or under occlusive dressings
- AVOID soap except in body folds
Cream for localized dermatitis
- Low potency: desonide BID
- Medium potency: Triamcinoline/mometasone/fluocinolone BID
- Non-steroidals (only use if >2y): Tacrolimus/pimecrolimus/crisaborole
Systemic tx for atopic dermatitis
Dupulimab SC
Tx for pruritis in atopic dermatitis
- Benadryl
- Hydroxyzine
- Zyrtec
- Claritin
Antihistamines
How do you differentiate between irritant contact dermatitis vs allergic contact dermatitis?
- ICD: confined to area, sharply marginated, never spreads
- ACD: spreading, type IV HSR
Where does airborne contact dermatitis tend to affect?
- Face (upper eyelids)
- Neck
- Upper chest
- Forearms
- Hands (palmar)
AKA exposed skin
How do you test for contact dermatitis?
- Hx
- Patch testing ((+) still requires you to clinically correlate)
- Do not use skin prick test, which only tests Type 1 HSR
Patch testing is not the same as skin prick testing
What is the underlying physiology of allergic contact dermatitis?
Haptens, which bind to a carrier and cause a Type IV HSR
Re-exposure to a substance already sensitized to
Tx of allergic contact dermatitis
- Avoid offending agents
- Topical steroids (2wk on, 2wk off)
- Oral steroids
What non-pharmacological therapy can help with contact dermatitis?
PUVA Phototherapy
What can cause diaper dermatitis?
- Cutaneous candidiasis
- ICD
- Miliaria (blocked sweat ducts)
Who is diaper dermatitis MC in?
3 weeks old to 2y in age
How does diaper dermatitis tend to present?
- Fussiness
- Crying during diaper change
- Diarrhea
- Shiny erythema with dull margins
- Potentially candidiasis or miliaria
Management of diaper dermatitis
- Change the diaper ofc
- Dry after bathing
- Barrier creams (zinc oxide/petroleum jelly)
- If candidiasis: nystatin/clotrimazole/econazole
How does nummular eczema present?
Like atopic dermatitis but no HX/FHx of atopy
Ring-shaped
Who is nummular eczema MC in and what predisposing factor may result in lesions on the legs?
- MC in 50-65y men
- Venous stasis will lead to lesions on the legs
What is nummular eczema associated with?
- Frequent bathing
- Low humidity
- Irritating/drying soaps
- Interferon therapy for Hep C
- Exposure to irritating fabrics
Irritants and drying
Where is nummular eczema MC found on the body?
Trunk and extremities
How is nummular eczema diagnosed?
Clinically, but you can do cultures if bacteria, scrapings if fungus, and biopsy if necessary
How do you treat nummular eczema?
The same as atopic dermatitis:
- Gentle cleansers
- Low strength steroids