Inflammatory Skin Disease (complete) Flashcards
What are common causes of irritant and allergic contact dermatitis?
1) Atopic Dermatitis
What is atopic dermatitis?
- Common skin disease
- Can begin at any age (majority <5yo)
What are the diagnostic criteria for atopic dermatitis?
MUST HAVE: itchy skin and three or more of the following:
- H/o of skin crease involvement
- H/o asthma or hay fever
- H/o dry skin in last year
- Visible flexural eczema
- Onset under 2 years
What is the pathogenesis of atopic dermatitis?
- Barrier disrupted skin
- Filaggrin mutation
- S. aureus acts as superAg
- Elevated IgE
- Eosinophilia
- Th2 cytokine production (IL4,5,&10)
Describe infantile atopic dermatitis
Birth - 2 yo
- Dry, red scaly areas — confined to cheeks
- Becomes flushed w/ exposure to cold
- Some will have a generalized eruption (erythematous papules, redness, scaling, areas of lichenification)
Describe childhood atopic dermatitis
Involvement of flexural skin
- antecubital fossa
- popliteal fossa
- neck
- wrists
- ankles
Describe adult atopic dermatitis
- occurs on eyelid and/or hand
Characterized by:
- dry skin
- keratosis pilaris
- ichthyosis vulgaris
- hyperlinearity of palms
Describe irritant contact dermatitis
- non-immunological mediated rxn => direct cytotoxic effect
- Can be from a single/repeated exposure
- MOST COMMON type of contact dermatitis
No specific test for irritant contact dermatitis
What are the effects of strong irritants associated w/ irritant contact dermatitis?
- Damage skin directly (even w/ small amounts for short time)
- These agents carry warning labels => suggest wearing gloves
Weak irritants are harmless by themselves but frequent contact may damage skin
What are some examples of weak irritants?
- Soap/water
- Skin products
- Perfumes
- Wool
- Raw foods
- Body secretion
- Friction
Describe allergic contact dermatitis
- Requires exposure of allergen => immune response & development of memory T cells
- Type 4 delayed-type hypersensitivity rxn => starts 24-48hrs after exposure
Think poison ivy
Describe allergic contact dermatitis on a micro level
- Allergens small chemicals => <500 daltons
- Smallness allows penetration through skin
- Langerhans cells present allergen to T cells
- Require repeat exposure
- Caused by inflammatory cytokines including TNF-alpha and IL-1
What do you patch test?
- Used for diagnosing allergic contact dermatitis
- pts have suggestive history
- pts w/ resistant dermatitis
- chronic dermatitis
- occupationally related dermatitis
- Atopic eczema
- stasis dermatitis
- photo/airborne distribution
What are some contact allergens?
- Nickel
- Balsma of Peru
- Neomycin
- Fragrances
What are some risk factors associated with nickel sensitivity?
- Being female
- Younger age
- Ear piercing
Describe fragrance allergies
- > 2800 fragrance ingredients
- > 100 are known contact allergens
- Unscented products may have a masking fragrance — need to use fragrance-free products
Describe bacitracin and neomycin allergies
- Can occur together
- Co-sensitization: allergy to two allergens not structurally related but often used together
What are drug eruptions?
Delayed-typer hypersensitivity rxns
- Most common type
- Usually Type 4 hypersensitivity
Usually begins 7-14 days after starting new med
Describe exanthematous eruptions
- 10-20% in children are drug-induced
- 50-70% in adults are drug-induced
Tx: stop cause (infection), supportive w/ topical steroids, anti-histamines
What are some responsible drugs associated with exanthematous eruptions?
- AminoPCNs
- Sulfonamides
- Cephalosporins
- Anticonvulsants
- Allopurinol
Describe stasis dermatitis
- Associated w/ other signs of venous insufficiency
- ONLY in lower extrememties
Think:
- Varicose veins
- Chronic lower extremity edema
- Venous stasis ulcers
- Lipodermatosclerosis
What are complicating factors associated with stasis dermatitis?
- dryness
- itching
- allergic contact dermatitis
- irritant dermatitis due to wound exudates
What is the treatment for stasis dermatitis
- Compression
- Elevation
- Exercise calf muscles
- Vascular surgery
- Topical steroids
- Avoid allergens
What is lichen simplex chronicus?
- thick, scaly plaques
- Cause: chronic rubbing, scratching
- Tx: topical steroids first, then antihistamines
Pts need to be counseled to break cycle
Describe venous stasis ulcers
- Common in pts w/ h/o leg edema, varicose veins, blood clots
- Found in medial lower leg
- Red w/ yellow fibrinous base
- Borders irregularly shaped
- May be purulent
Describe nummular dermatitis
AKA: discoid eczema
- Often in legs, but also arms, trunk
- Most common in men >50yo
- round patches: red, scaly, crusty
- Tx: moisturization, minimize soap, topical steroids
What is the morphology of dermatitis?
- Erythematous papules
- Thin plaques w/ scale
What is the morphology of erysipelas?
Warm, tender, erythematous, sharply demarcated, raised plaque
What is the morphology of cellulitis?
Warm, tender, erythematous patches OR plaques
Where is the inflammation in dermatitis?
- Epidermis
- Dermis
Where is the inflammation in erysipelas?
- Dermis
- minimal SubQ tissue
Where is the inflammation in cellulitis?
- Dermis
- SubQ tissue
Describe seborrheic dermatitis
- Facial involvement
- Symmetric over medial eyebrows, nasolabial folds, ears
- Occurs in areas w/ sebaceous glands (scalp, face, ears, chest)
- ALSO dandruff
Describe the pathogenesis of seborrheic dermatitis
- Maybe b/c of a combo of overproduction of skin oil and yeast irritation (malassezia furfur)
- Increased disease linked to Parkinsons, head injury, stroke, HIV
Describe psoriasis
- Affects 2% of pop’n
- Positive FH in 36% of psoriasis
- Impacts QOL
Clinical:
- Chronic plaque disease
- Guttate
- Erythroderma
- Pustular psoriasis
- Arthritis
What are co-morbidities associated w/ psoriasis?
- Independent risk factor for CV disease
- Pts in 40s: double risk for MI, RR increases by 20%
Describe the treatment in localized psoriasis
- Calcipotriol
- Corticosteroids
- Topical retinoids
- Phototherapy
Describe the treatment in widespread psoriasis w/ or w/o arthritis
- Methotrexate
- Cyclosporin
- Systemic retinoids
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Where does stasis derm present?
Lower legs
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Where does seborrheic derm present?
Scalp
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Where does atopic derm present?
Flexor surfaces
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Where does psoriasis present?
Extensor surfaces
May include arthritis
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What is the cause of stasis derm?
Lower extremity edema
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What is the cause of seborrheic derm?
Malassezia furfur
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What is the cause of atopic derm?
Filaggrin
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What is the cause of irritant derm?
Common irritants
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What is the cause of allergic contact derm?
Common allergens
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What is atopic dermatitis associated with?
Asthma
Allergic rhinitis
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What type of hypersensitivity is associated with allergic contact dermatitis?
Type 4 (delayed type hypersens rxn)
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How is allergic contact dermatitis tested for?
Patch testing
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What is psoriasis associated with?
Increased risk for CV disease
