Environmental, cultural, occupational, genetic, individual, and racial differences are important in the study of contact dermatitis.
Two important differences in skin physiology that determine the relationship between skin of color and contact dermatitis are barrier function and percutaneous absorption.
Allergic contact dermatitis (ACD) in patients with skin of color could be more commonly associated with lichenification and hyperpigmentation than the vesicular, papular, and erythematous response often seen in Caucasians.
Interpreting the results of a patch test in patients with skin of color is more difficult, particularly given the challenge of detecting erythema. This leads to an underestimation of ACD in skin of color.
Contact dermatitis is an altered state of skin reactivity induced by exposure to an external agent. Certainly, sex, age, and environmental, occupational, and genetic factors are thought to be important in the study of contact dermatitis. However, the effect of contact dermatitis on people with skin of color has been studied less frequently. One of the most frequent pathologic manifestations of the skin is contact dermatatitis.1 It is divided into two basic types depending on the nature of the underlying etiologic mechanism: irritant and allergic [Figure 28-1].
Contact dermatitis on the back of a female patient with skin of color.
In the United States, the prevalence of contact dermatitis is estimated to be between 1.5% and 5.4%, and it is the third most common reason that a patient consults a dermatologist.2 The frequency of allergic contact dermatitis (ACD) is hard to determine exactly. Of 4913 patients patch tested in the North American Contact Dermatitis Group study, 69% had at least one positive allergic reaction and 15.4% had irritant contact dermatitis (ICD).3 Similar results were found in a retrospective study in Kansas, which found that 68.6% of patients had at least one positive allergic reaction.4 However, over a 15-year cohort study, incidence rates of contact allergy and ACD were 13.4% and 7.8%, respectively.5 The real prevalence of the disease is unknown because it is frequently misdiagnosed as other kinds of eczema.6 ACD is therefore an important dermatologic disease with considerable morbidity and economic impact.
ICD occurs when a chemical agent induces direct damage to the skin and produces inflammation without the classic ‘allergic’ mechanism. The clinical manifestations can be subtle, such as a stinging sensation on exposure, or marked, such as severe chemical burns. The timing of the reaction varies according to exposure—usually occurring within a short period of minutes for a single exposure and within days or weeks for multiple exposures. Most irritant reactions seen in the clinic are of moderate severity, and are due to cumulative insult with mildly toxic substances, such as ordinary soap and water.2
ACD occurs when contact with a specific allergen or a closely related ...