History
A detailed history should be performed for any individual suspected of having protein contact dermatitis (PCD). While not confirmed with formal studies, anecdotal risk factors for the development of protein contact dermatitis include a history of atopy, chronic irritant dermatitis, and an occupation or hobby involving exposure to protein allergens. Persons at particular occupational risk include kitchen workers, food vendors, gardeners, slaughterhouse workers, butchers, commercial anglers, farmers, and veterinarians.
Many agents are capable of causing protein contact dermatitis, as is elucidated in Etiology. Identification of the agent may be aided by the rapid onset of the reaction upon exposure: an acute, urticarial, or vesicular eruption may occur within minutes after contact with the causative protein. A chronic recurrent dermatitis also ensues at the site of allergen application.
Patients may report itching, burning, stinging, or pain in the affected area. Upon ingestion of the allergen, patients may rarely experience angioedema, rhinoconjunctivitis, gastrointestinal symptoms, and/or bronchial asthma.
The International Contact Dermatitis Research Group proposed a classification for contact allergies based on clinical presentation. [22]
Physical Examination
Protein contact dermatitis is characterized by pruritic, erythematous papules and vesicles with overlying fine scale. Lichenification may occur, especially with long-term exposure. The dermatitis usually affects the hands and forearms, which are typically diffusely involved. Sometimes, only the fingertips are affected. Paronychia and periungual edema and erythema may be observed. [23] Urticarial papules and plaques may occur within minutes following contact with the causative allergen, although, in one large series, this was rarely observed. [24] Paronychia with periungual erythematous edema is suggestive of a diagnosis of protein contact dermatitis. [13, 19] In one report, a fixed pigmented erythema with central bullae was observed. [19]
