Irritant and contact dermatitis Flashcards
What is irritant contact dermatitis (ICD)?
Localized, non-immunologically mediated cutaneous inflammatory reaction. Secondary to direct exposure to a topical external agent
ICD accounts for how much of contact dermatitis?
80%
Does ICD require previous exposure to agent?
No
How long does it take for ICD to occur?
Usually within a few minutes or hours
Describe acute phase of ICD
Erythema, edema and vesiculation followed by erosions and scaling
Describe chronic phase of ICD
Erythema, lichenification, fissures and scale
Areas commonly affected by ICD?
Hands (soaps, wet work, acids, solvents, alcohols, cleansers, food, plants, etc), lips (lip licking)
Describe pathology of ICD
Trauma from offensive physical or chemical agents creates cytotoxic epidermal damage, leading to a series of specific alterations to structure and function of skin –> lipids stripped –> TEWL –> activation of keritinoncytes and innate immune system –> release of proinflammatory cytokines –> activate t-cells –> Langerhans cells emerge –> increased inflammatory reaction
Differential for ICD?
ACD, dyshidrotic eczema, endogenous eczema, thermal burn
History questions for ICD
Occupation? Do sx improve with time off? Hobbies? What sort of materials handled? History of eczema as a child?
Treatment of ICD?
Avoidance of irritant, protective clothing and barriers, topical corticosteroids, good skin hygiene
What is allergic contact dermatitis (ACD)?
A localized, cutaneous delayed hypersensitivity inflammatory reaction.
What is the first symptom of ACD?
Pruritus during acute phase
Does patient need to be previously sensitized to agent in ACD?
Yes
Describe acute phase of ACD
Erythema, edema vesicobullae, weeping and pruritus
Describe chronic phase of ACD
Lichenified with scale. Can mimic ICD.
Does ACD involve more than affected area?
Can have auto-sensitization with extension beyond original site
How long does it take for ACD to occur?
Primary exposure- sensitization phase 14-21 days after exposure
Subsequent exposures- 12-48 hr after exposure
Differential of ACD
ICD, atopic dermatitis, stasis dermatitis, seb derm, roscacea
Diagnostic work up of ACD
Patch testing
Treatment of ACD
Avoidance of allergen, topical and/or systemic corticosteroids
What is systemic contact dermatitis?
Systemic exposure to an allergen to which the patient has had prior sensitization (administration of oral diphenhydramine to a patient previously sensitized to topical formulation)
What sorts of reactions can plants cause?
ACD, ICD, urticaria and phytophotodermatitis
Plants, commonly poison ivy, containing what cause ACD?
Urushiol
How long to treat poison ivy?
A sensitized person develops rash in about 2 days and it can last for 2-3 weeks. Treat for at least 2 weeks to prevent rebound (no Medrol pack)
Is phytophotodermatitis an allergic reaction?
No. It is non-immunologic reaction. OCcurs after direct topical contact that acts as a photosensitizer
Clinical manifestations of phytophotodermatitis?
ERythema, vesicles/bullae, hyperpigmentation in streaks or bizarre formations.
Common plants that cause phytophotodermatitis?
Limes, celery
What plays a role in severity of reaction in ICD?
Individual sensitivity, amount of irritant exposed to and length of exposure
What happens with repeated exposures in ACD?
Worsening severity
