Faculty Bibliography

Allergic contact dermatitis is a prevalent burdensome condition affecting millions of Americans. Patch testing, the criterion-standard allergic contact dermatitis diagnostic tool, is underused by US dermatologists. Incorporating patch testing into modern dermatology practices is achievable with utilization of accurate resources and sustainable support. This review focuses on the basics of patch testing and provides practical pearls to assist novice providers in establishing a contact dermatitis specialty practice.

Allergic contact dermatitis (ACD) has been traditionally identified as TH1-mediated delayed-type hypersensitivity reactions. There is currently no Food and Drug Administration-approved systemic therapy indicated for ACD. Among patients with ACD, there is a subgroup that experience not only concomitant atopic dermatitis and ACD but also systemic allergic dermatitis driven by allergens encountered through dietary consumption. Basic science and clinical studies have supported the notion that ACD involves a complex interaction between both TH1 and TH2 axes of the secondary immune system on an allergen-by-allergen basis. Herein, we report the patients with systemic allergy syndrome with dermatitis to either Balsam of Peru or nickel who achieved remarkable improvement and regained their quality of life without continuing adherence to strict diets. Our study suggests that dupilumab may be an efficacious solution for a particular subgroup of patients with recalcitrant ACD when first- and second-line therapies have failed.

Systemic contact dermatitis (SCD) describes a hypersensitivity reaction following systemic re-exposure of the inciting allergen in previously sensitized individuals. Plants, drugs, and metals are the most common causes of SCD. In individuals with obstinate dermatitis, it is imperative to deliver and history-focused patch testing with subsequent avoidance and elimination of the compound.

Allergic contact dermatitis is a common disease within the family of delayed-type hypersensitivity reactions. In more severe cases of allergic contact dermatitis, topical steroids may prove insufficient, and systemic therapeutic agents are often used. Even when systemic therapies such as cyclosporine lead to improvement, withdrawal of these agents is challenging and can lead to undesirable morbidities. Currently, there are no systemic treatments indicated for the treatment of widespread recalcitrant contact dermatitis. This review discusses the targets of in-use off-label systemic medications and potential therapeutics in the pipeline.

: Carmine is a widely used "natural" food additive that has been reported to provoke both an immediate hypersensitivity and a delayed systemic response with cutaneous expression. Systemic contact dermatitis describes the hypersensitivity reaction following systemic re-exposure of the inciting allergen in previously sensitized individuals. In individuals with recalcitrant dermatitis and a positive carmine intolerance history and/or patch test, it is important to consider a trial topical and dietary elimination of carmine-associated products and foods.

Allergic contact dermatitis is associated with significant disease and economic burden in the United States. To properly manage allergic contact dermatitis, it is important to accurately identify the substance(s) implicated in the dermatitis to prevent disease recurrence. The commercially available T.R.U.E Test (36 allergens) screening panel has been reported to have a conservative hypothetical allergen detection rate of 66.0%, at most. Importantly, these calculations are based on the 78% of patients who had clinically relevant reactions to allergens present on the North American Contact Dermatitis Group screening series (70 allergens), without the use of supplemental allergens. Testing with supplemental allergens beyond a screening series can more fully evaluate an individual's environmental and occupational exposure, which may significantly increase diagnostic accuracy. Comprehensive patch testing with additional allergens in sunscreens, cosmetics, and fragrances, for example, may increase the diagnostic yield as well as the likelihood of achieving a cure if the dermatitis is chronic and recalcitrant.