Contact Dermatitis Flashcards
What is contact dermatitis?
An inflammatory skin reaction caused by direct contact with an irritant or allergen.
What are the two main types of contact dermatitis?
Irritant Contact Dermatitis (ICD) – Non-immunologic reaction caused by direct damage to the skin by a substance.
Allergic Contact Dermatitis (ACD) – Delayed hypersensitivity (type IV) reaction triggered by contact with an allergen.
Name common irritants that cause irritant contact dermatitis.
Soaps, detergents, solvents, acids, alkalis, and prolonged water exposure.
Name common allergens that cause allergic contact dermatitis.
Nickel, fragrances, cosmetics, latex, preservatives, and poison ivy (urushiol).
What is the primary mechanism of irritant contact dermatitis?
Direct cytotoxic effect on keratinocytes, causing inflammation and disruption of the skin barrier.
What is the primary mechanism of allergic contact dermatitis?
Allergen-specific T-cell mediated delayed hypersensitivity (type IV reaction).
What are the hallmark symptoms of irritant contact dermatitis?
Burning, stinging, erythema, dryness, scaling, and fissuring, often confined to the site of exposure.
How does allergic contact dermatitis typically present?
Pruritic, eczematous lesions (papules, vesicles, or plaques) that may extend beyond the area of direct contact.
How is contact dermatitis diagnosed?
Clinical evaluation based on history, exposure patterns, and physical exam findings.
What diagnostic test confirms allergic contact dermatitis?
Patch testing, which identifies specific allergens causing the hypersensitivity reaction.
What findings differentiate irritant from allergic contact dermatitis?
Irritant Contact Dermatitis: Immediate onset, localized to contact area, no prior sensitization needed.
Allergic Contact Dermatitis: Delayed onset (48–96 hours), may extend beyond the contact site, requires prior sensitization.
What is the cornerstone of management for contact dermatitis?
Avoidance of the identified irritant or allergen.
What topical treatments are commonly used for contact dermatitis?
Topical corticosteroids to reduce inflammation.
Emollients to restore the skin barrier.
When are systemic treatments needed for contact dermatitis?
For severe cases, widespread lesions, or significant pruritus, systemic corticosteroids (e.g., prednisone) or antihistamines may be used.
What is the mainstay of topical treatment for contact dermatitis?
Topical corticosteroids to reduce inflammation and pruritus.
Name examples of low-potency topical corticosteroids and their indications.
Hydrocortisone 1% or 2.5%—used for mild dermatitis or sensitive areas like the face and intertriginous zones.
Name examples of high-potency topical corticosteroids and their indications.
Betamethasone dipropionate, clobetasol propionate—used for severe dermatitis on thicker skin areas like palms or soles.
What are potential side effects of prolonged topical corticosteroid use?
Skin atrophy, striae, telangiectasia, and tachyphylaxis (reduced efficacy over time).
What non-steroidal topical treatments are available for contact dermatitis?
Topical calcineurin inhibitors: Tacrolimus or pimecrolimus, particularly for sensitive areas like the face or groin.
Barrier creams: Contain zinc oxide or dimethicone to protect against irritants
Why might topical calcineurin inhibitors be preferred over steroids?
They avoid steroid-related side effects, especially skin thinning, and are suitable for long-term use.
When are systemic corticosteroids indicated in contact dermatitis?
For severe, extensive, or refractory cases involving widespread inflammation.
What is a typical systemic corticosteroid regimen for severe cases?
Prednisone 0.5–1 mg/kg/day tapered over 2–3 weeks to prevent rebound dermatitis.
What role do emollients play in managing contact dermatitis?
They restore the skin barrier, reduce dryness, and promote healing.
Name examples of emollients useful for contact dermatitis.
Petroleum-based ointments, creams with ceramides, or urea-based moisturizers.
