dermatitis: itchy red rashes jerry tan md frcp university of w estern ontario w
TRANSCRIPT
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Dermatitis: Itchy Red Rashes
Jerry Tan MD FRCP University of W estern Ontario
W
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Objectives
• Describe the cutaneous features of dermatitis
• Differentiate acute from chronic dermatitis
• Contrast irritant versus allergic contact dermatitis
• Describe the presentation of atopic dermatitis at
different ages
• Indicate cutaneous findings that are unique for
each type of dermatitis
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Dermatitis (syn. eczema)
• Skin inflammation characterized by:
itchy, scaly, patches of ill-defined erythema
• Common reaction pattern of various pathogenic
pathways:
Epidermal barrier disruption
Type IV immune injury
Combinations of the above
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Acute dermatitis
erythema and edema
papules, vesicles, and
sometimes bullae
accompanied by
exudation and crusting
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Chronic dermatitis
less erythema and
edema
presence of
lichenification, scaling,
and fissuring
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Contact Dermatitis
= dermatitis precipitated by an exogenous agent
2 types:
allergic (hypersensitivity) or
irritant (direct noxious effect on skin)
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Irritant contact dermatitis
More common than allergic contact dermatitis
Results from chronic exposure to irritants that
progressively disrupt the epidermal barrier
Most common irritants are:
Water
Abrasives
Chemicals, e.g. acids and alkalis
Solvents and detergents
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Eg. Irritant contact hand dermatitis
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Allergic contact dermatitis
Due to type IV immune response by specific allergen
requires induction and elicitation phase (lag time to
reaction)
Common allergens eliciting contact dermatitis: •
•
•
•
nickel (affects 10% of women and 1% of men),
perfumes,
hair dyes,
rubber latex
• Suspect if dermatitis shows geometric patterns
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Nickel Allergy - belt buckle
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Nickel Allergy - bracelet
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Hair dye allergy
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Hair dye allergy
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Latex allergy - goggles
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Adhesive allergy - bandage
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Allergy to leather sandal straps
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Management
Primary objective:
Identify offending allergen or irritant
Flare diaries; allergic contact patch
testing
Avoidance of allergen(s) / irritants.
Treatment: Gentle cleansers
Barrier creams
Topical anti-inflammatory medications
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Atopic Dermatitis
= chronic pruritic inflammatory
dermatosis
associated with personal or
family history of asthma,
allergic rhinitis, conjunctivitis
or atopic eczema.
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Atopy
defines an inherited tendency,
present in 15-25% of the population,
to develop one or more of: asthma, allergic
rhinitis/conjuncitivitis, atopic eczema
Cause of atopic dermatitis:
defective epidermal differentiation (filaggrin mutations) and
resultant impaired barrier function of the skin
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Br J Derm 2007, 157: 441
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Infantile atopic dermatitis
Infants develop an itchy
vesicular eczema on
cheeks and hands
often with secondary
infection.
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scaling
erythema
fissures
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Childhood atopic dermatitis
Children develop lesions @ antecubital and popliteal
fossae, neck, wrists, and ankles.
Lichenification, excoriations, and dry skin are common
as well as post-inflammatory hyperpigmentation.
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Flexural involvement
xerosis
excoriations
Erythematous patches, fissures
hyperpigmentation
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Lichenification Accentuation of normal skin markings
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Adult atopic dermatitis
In adults
most common manifestation: hand dermatitis.
chronic severe form of generalized and lichenified
atopic eczema.
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Hand dermatitis
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Widespread chronic atopic dermatitis
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Complications of atopic dermatitis
Infection:
Bacterial infection: impetigo
Viral infection
eczema herpeticum
(HSV)
widespread mollusca
Cataracts Growth retardation
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Impetiginised dermatitis
Golden yellow crust
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Impetiginised dermatitis
Fragile bullae with crust and erosions = bullous impetigo
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Eczema Herpeticum
Extensive facial erosions More tender than typical eczema
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Mollusca Contagiosa
Dome-shaped 1-2mm firm papules
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Management
Education
Avoidance of irritants
sweat, wool, pet dander
Mild cleansers, frequent moisturisation
Prescribe the least potent topical anti-inflammatory
(steroid, TIMs) that is effective.
Antibiotics (topical or oral) for infected eczema.
+/- oral antihistamines for pruritus
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Topical Steroid Classification
Potency Products
Hydrocortisone acetate 1%
Comments
Facial and intertriginous Low
Moderate
Strong
Ultra
Desonide
Betamethasone valerate Triamcinolone acetonide Mometasone
Amcinonide Betamethasone dipropionate
Clobetasol, Halobetasol
regions Elidel* equivalent
Protopic* 0.1% equivalent
Limit use to max 1 wk/ mth Reassess frequently
*Non-steroidal antiinflammatory medications
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Seborrheic dermatitis
chronic, scaly inflammatory eruption usually
affecting scalp and face
Can also affect chest, and flexures (axillae, groin, and
infra-mammary areas)
due to overgrowth of the commensal yeast
Pityrosporum ovale.
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Seborrheic dermatitis
•Persistent
erythematous patches
with greasy scales
•Characteristic
distribution: sides of
nose, glabella,
perioral region, scalp,
eyebrows, ears;
chest.
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Seborrheic dermatitis
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Truncal seborrheic dermatitis
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Management
Scalp:
medicated shampoo (e.g. containing coal tar,
selenium sulphide or ketoconazole)
Face, trunk, flexures:
imidazole or antimicrobial, often combined with low
potency topical steroid
eg HC 1% in Canesten Cream bid
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Nummular Eczema
Distinctive eczema with itchy coin-shaped
macules/patches
typically affects limbs of middle-aged or elderly
Management:
emollient,
topical steroid
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Nummular Eczema
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Venous (Stasis) Eczema
affects sites of stasis edema (lower legs)
most patients are middle-aged or elderly
Complications: ulcers, infections
Management: • Treatment of edema
• Support stockings, leg elevation, diuretics
• Skin treatment: emollient +/- steroid ointment
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Stasis eczema
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Stasis eczema
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Xerotic dermatitis
Diffuse background skin dryness with associated
dermatitis
typically affects limbs of the elderly.
Aggravated by:
harsh cleansers, dry winter conditions, hypothyroidism, use of
diuretics
Treat with emollients 1st;
+/- mild steroid ointments
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Xerotic dermatitis
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What unique features are associated with different types
of dermatitis?
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Distinctive morphological features of different forms of dermatitis
type Features of dermatitis Other skin findings
atopic Symmetry, changes with age xerosis
seborrheic Greasy scale, face and scalp affected oiliness
nummular
stasis
xerotic
Coin-shaped or discoid macules and patches
Affects lower legs, ankles
Mild, widespread; typically fall & winter
xerosis
Edema, hyperpigmentation
xerosis
allergic contact sites of contact,
may have geometric patterns
irritant contact typically affects hands, face Xerosis, fissuring
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Summary
• Describe the cutaneous features of dermatitis
• Differentiate acute from chronic dermatitis
• Contrast irritant versus allergic contact dermatitis
• Describe the presentation of atopic dermatitis at
different ages
• Indicate cutaneous findings that are unique for
each type of dermatitis
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Acknowledgements References:
Shear, Knowles and Shapiro Cutaneous Drug Reactions, Web MD Scientific American, Feb 2001.
Lebwohl, M: Cutaneous Manifestations of Systemic Diseases, WebMD Scientific American Medicine, June 2003 update.
Gawkrodger DJ. Dermatology an illustrated color text. Churchill Livingstone 2001
Illustrations: Dermatology Image Atlas: www.dermatlas.org
www.dermis.net www.derm101.com