Contact Dermatitis

Basics

Basics

Basics

DESCRIPTION

DESCRIPTION

DESCRIPTION

An acute or chronic inflammation of the dermis and epidermis as result of either direct irritation to the skin (irritant contact dermatitis) or delayed-type (type IV) hypersensitivity reaction to a contact allergen (allergic contact dermatitis)

EPIDEMIOLOGY

EPIDEMIOLOGY

EPIDEMIOLOGY

INCIDENCE

INCIDENCE

INCIDENCE

Incidence in children is not known.

PREVALENCE

PREVALENCE

PREVALENCE

  • Irritant contact dermatitis: Most cases of contact dermatitis (>80%) are due to irritants.
    • Skin reactivity is highest in infants and tends to decrease with age.
  • Allergic contact dermatitis
    • Because children have less time to develop sensitivities, it is less common in infants and children than in adults.
    • Prevalence increases with age.
    • Overall prevalence is ~13–23% and has been increasing in children, perhaps due to more frequent exposure to allergens at a younger age or improved diagnosis.
    • Contact sensitization may complicate the course in >40% of patients with atopic dermatitis.

RISK-FACTORS

RISK-FACTORS

RISK-FACTORS

  • Irritant contact dermatitis
    • Frequent hand washing or water immersion
    • Atopic dermatitis: Chronically impaired barrier function increases susceptibility to irritants.
    • Genetic factors
    • Environmental factors such as cold/hot temperatures or high/low humidity disrupt the skin barrier.
  • Allergic contact dermatitis
    • Atopic dermatitis
    • Skin barrier disruption from injuries or wounds
    • Genetic factors
    • Increased exposure to allergens

GENERAL-PREVENTION

GENERAL-PREVENTION

GENERAL-PREVENTION

Minimize contact exposure to known or potential irritants and allergens and maintain the barrier function of the skin.

PATHOPHYSIOLOGY

PATHOPHYSIOLOGY

PATHOPHYSIOLOGY

  • Irritant contact dermatitis does not involve an immune response and thus can occur with the first exposure to the irritant. Multiple mechanisms are involved, including:
    • Direct damage to keratinocytes by chemicals (soaps, detergents) or physical irritants (moisture, friction) with resulting disruption of the epidermal barrier and localized release of proinflammatory cytokines
    • Chronic exposure may stimulate cell proliferation, resulting in acanthosis and hyperkeratosis with postinflammatory hypo- or hyperpigmentation.
  • Allergic contact dermatitis requires initial exposure and sensitization to an allergen and only occurs in susceptible individuals. Repeated exposure leads to the development of a type IV hypersensitivity reaction resulting in proliferation of sensitized T lymphocytes.
    • Strong antigens may require only one exposure, whereas weaker antigens may require multiple.
    • Exposure can occur transepidermally or systemically.
  • Both processes result in nonspecific findings of dermal and epidermal edema and inflammation and may be indistinguishable from other forms of inflammatory dermatitis.

ETIOLOGY

ETIOLOGY

ETIOLOGY

  • Irritant contact dermatitis
    • Frequent hand washing or water immersion
    • Soaps and detergents
    • Saliva (lip licking or thumb sucking)
    • Urine and feces (see “Diaper Rash”)
    • High concentrations of most chemicals can induce irritant contact dermatitis, whereas mild irritants may induce inflammation only in susceptible individuals.
  • Allergic contact dermatitis
    • Nickel and other metals (gold, cobalt)
    • Hair products (ammonium, 5-diamine)
    • Solvents (toluene-2)
    • Cleansers, shampoos (cocamidopropyl betaine)
    • Additives to medications, cosmetics (thimerosal, mercuric chloride)
    • Rubber
    • Fragrances (balsam of Peru [BOP])
    • Dyes (cobalt, potassium dichromate, black henna)
    • Formaldehydes
    • Topical antibiotics (neomycin, bacitracin)
    • Topical corticosteroids
    • Emollient components (lanolin alcohol)
    • Plants (Toxicodendron species; e.g., poison ivy, poison oak, and poison sumac, which contain the allergen urushiol)

ASSOCIATED-CONDITIONS

ASSOCIATED-CONDITIONS

ASSOCIATED-CONDITIONS

Atopic dermatitis or other chronic dermatoses

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