Patch testing while immunosuppressed: potential risks and benefits

INTRODUCTION

Allergic contact dermatitis (ACD) is a common cutaneous inflammatory skin disorder that is diagnosed via epicutaneous patch testing (PT). ACD may also coexist with other systemic inflammatory conditions such as atopic dermatitis and psoriasis. Many of the treatments used to manage severe ACD, along with other systemic conditions, interact with and suppress the immune system, thereby potentially interfering with the mechanism of PT. There is uncertainty in the literature regarding the effects of immunosuppression on the results of PT.

METHODS

A comprehensive literature review was conducted using PubMed and Google Scholar to identify articles relevant to the topic of this review. Only articles available in English were included.

AREAS COVERED

This review discusses the impact of immunomodulating therapies on the results of PT. We summarize the available evidence and provide updated recommendations for several immunomodulating drugs commonly used in patients undergoing PT.

EXPERT OPINION

In general, the results of PT are most reliable when performed without immunosuppression. If this is not feasible, it is best to have patients on as low a dose of immunosuppression as possible, but it may not be necessary to stop or change an immunomodulating drug prior to PT.

Overcoming False-Negative Patch Tests: A Systematic Literature Review

Exogenous allergens, found in cosmetic products, jewelry items, antiseptics and antibacterials, plants, and solvents, can cause clinical allergic contact dermatitis (ACD). To help identify and discern which allergen is causing ACD, clinicians use patch tests, but they can yield false-negative results at times. Examining potential reasoning for false negatives is particularly helpful when a patient's history and physical examination strongly suggest ACD, and the patch test is negative. A strong history and physical presentation suggestive of ACD warrants additional patch testing or other methods to verify a false-negative patch test result. We conducted a literature review to compile various reasonings and solutions for false-negative patch tests in suspected ACD patients. Utilizing EMBASE, Scopus, PubMed, and Google Scholars, 49 articles were included by using search terms such as "False negative patch test" or "False-negative patch test" and "allergic contact dermatitis," or "ACD." Common factors that led to false-negative patch test results include low allergen concentration, inadequate percutaneous penetration, technique error, immunosuppressive therapy, and ultraviolet exposure. Potential solutions include using different vehicles, concentration, increasing reading time, repeating the patch test, intradermal testing, and repeat open application testing. If a false-negative patch test is suspected, then intradermal testing can be administered to ensure the specificity of the patch test result. Considering the main contributing factors and solutions to false-negative patch tests, clinicians can accurately diagnose ACD and administer proper treatment plans.

What We Have Learned–Milestones in Pediatric Contact Dermatitis

Purpose of Review

This review highlights recent developments in the field of pediatric allergic contact dermatitis (ACD) and patch testing. We will review updates on the pathophysiology of contact dermatitis, discuss new contact allergens, explore the impact of dupilumab on patch testing, and provide pearls for the diagnosis and management of ACD in children.

Recent Findings

ACD is not a single immunologic phenomenon but rather has contributions from multiple inflammatory pathways. Emerging contact allergens include ingredients found in “slime” toys, glucose monitors and insulin pumps, and electronic equipment. Data thus far suggests that patch testing results are generally reliable in the face of concurrent dupilumab use.

Summary

ACD is likely underrecognized and underdiagnosed in pediatric patients, including infants and young children. Providers should keep patient-specific factors and emerging trends in mind when addressing suspected ACD, consider contact dermatitis when they encounter challenging cases of atypical, refractory, or chronic dermatitis, and feel comfortable performing patch testing in children.

Pediatric allergic contact dermatitis. Part 2: Patch testing series, procedure, and unique scenarios

Patch testing is the criterion standard for diagnosing allergic contact dermatitis. Causative allergens differ between children and adults, necessitating the development of pediatric-specific patch test series. The Pediatric Baseline Series was developed in 2018 through expert consensus and includes relevant pediatric allergens that dermatologists can use in practice. Obstacles in patch testing, such as the need for multiple office visits, length of patch application, and avoidance of sweat and water on the testing area, are particularly challenging for the pediatric population, and several strategies are proposed. Aside from formal patch testing, alternatives like the repeat open application test and empiric allergen avoidance can be helpful in children. The key to management of allergic contact dermatitis is allergen avoidance, with emphasis on the need to properly identify causative allergens. Continued data collection through registries allows for a better understanding of the diagnosis and management of pediatric allergic contact dermatitis.

Allergic Contact Dermatitis in Children: Recommendations for Patch Testing

PURPOSE OF REVIEW

Allergic contact dermatitis (ACD) affects 20% of children. However, diagnosis of ACD may be underreported in children due to lack of recognition. Patch testing is the gold standard for evaluation of ACD in children but poses unique challenges in this population.

RECENT FINDINGS

Recent studies highlight the significance of ACD and the utility of patch testing in children. Evaluation of ACD in children is difficult and requires knowledge of a child's exposure history, careful selection of allergens, and knowledge of specialized patch testing considerations to minimize irritation and maximize cooperation. Until recently, there were no agreed upon patch test series for children. In 2018, a comprehensive pediatric baseline series was published enabling thorough evaluation of ACD in children (Yu J, Atwater AR, Brod B, Chen JK, Chisolm SS, Cohen DE, et al. Dermatitis. 2018;29(4):206-12). This review provides an overview of the current literature, an update on pediatric ACD, and patch testing methods in children to effectively evaluate and manage ACD.