Excerpt from Dermatitis, Contact


Synonyms, Key Words, and Related Terms: allergic contact dermatitis, ACD, primary irritant dermatitis, photodermatitis, contact urticaria, irritative contact dermatitis, diaper dermatitis, photodermatitis, contact urticaria, phototoxic reactions, photoallergic reactions, cell-mediated type IV delayed hypersensitivity reaction, Toxicodendron, poison ivy, poison oak, poison sumac, type I IgE-mediated reaction, contact allergen

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Background: Contact dermatitis is an inflammatory response of the skin to an antigen or irritant. Contact dermatitis can cause discomfort and embarrassment and is the most common skin condition among workers' compensation claims.

Pathophysiology: The main pathologic feature of contact dermatitis is intercellular edema of the epidermis, which may result in intraepidermal vesicle and bullae formation in acute cases and papules, scaling, and lichenification in chronic cases. Within the dermal layer, various cells congregate around the dilated capillaries to aid in inflammatory response.

Primary irritant dermatitis results from direct injury to the skin. It affects individuals exposed to specific irritants and generally produces discomfort immediately following exposure.

Allergic contact dermatitis (ACD) affects only individuals previously sensitized to the contactant. It represents a delayed hypersensitivity reaction and requires several hours to complete the cascade of cellular immunity before symptoms manifest.

Frequency:

  • In the US: Among workers' compensation claims for dermatologic conditions, 90% are for contact dermatitis. The most common antigens are nickel, potassium dichromate, and paraphenylenediamine. Contact dermatitis is the reason for 4-7% of dermatology consults. Hand dermatitis affects 2% of the population at a given time, and 20% of females are affected at least once in their lifetime. Children of persons with contact dermatitis are 60% more likely to have positive patch tests.
  • Internationally: Contact allergens are the same in Europe as in the US. However, dermatitis caused by Toxicodendron species is unknown in Europe.

Mortality/Morbidity: Most cases of contact dermatitis are easily treated, but cases with an unrecognized etiology can result in long-term morbidity. In rare cases, epidermal contact with an allergen results in an immunoglobulin E (IgE)-mediated immediate hypersensitivity reaction causing anaphylactic shock. Anaphylactic shock, if untreated, can result in death.

Race: Contact dermatitis is thought to affect whites more frequently than other races. It may be just as common in blacks but more difficult to detect. Fair-skinned redheads are the most vulnerable.

Sex: The female-to-male ratio is 2:1. Women are at highest risk following childbirth.

Age:

  • Contact dermatitis is most common during adulthood but affects all ages.
  • Irritative contact dermatitis affects very young and very old patients more severely. The most common cause of ACD in elderly patients is topical medication.
  • Irritative dermatitis is common in infants. The most common cause is diaper dermatitis.Please click here to view the full topic text: Dermatitis, Contact