New positive patch test reactions on day 7-The additional value of the day 7 patch test reading

Just scratching the surface: A review of pediatric skin allergies

The skin is a large and sophisticated organ populated by innate and adaptive immune effector cells. These immune cells provide a critical first line of defense against pathogens, but genetic and environmental factors can lead to inappropriate signaling that may manifest as hypersensitivity. The most common cutaneous allergic disorders in children include atopic dermatitis, urticaria/angioedema, and contact dermatitis. In this review, we will briefly review these conditions, with a focus on recent developments in our understanding of the diagnosis and management of these disorders.

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.

Exploring the relationship between allergic contact dermatitis and atopic dermatitis in children: insights from a retrospective patch testing analysis

BACKGROUND

Recent years have seen significant exploration into the potential link between allergic contact dermatitis and atopic dermatitis, yielding contradictory findings.

METHODS

A retrospective cohort analysis of children aged 2 to 18 who underwent patch testing at the pediatric dermatology clinic at a tertiary medical center in Israel was conducted.

RESULTS

Overall, 367 patients were included in the study, 31.6% of whom were diagnosed with atopic dermatitis. 160 children (43.6%) exhibited a positive reaction to at least one compound in the European baseline series. There was no statistically significant difference in reactivity between children with atopic dermatitis and those without (P = 0.848). Sub-analyses based on ethnicity, gender, and age did not reveal significant differences in overall European baseline series reactivity (P = 0.612, P = 0.446, P = 0.488, respectively). Sensitivity was notably higher when patch readings were conducted 72 h after application compared to 48 h [0.95 (CI: 0.91-0.97) vs. 0.60 (CI: 0.55-0.66)].

CONCLUSIONS

Patch testing is imperative for suspected cases of allergic contact dermatitis in all children, regardless of their atopic background. Further research is warranted to potentially replace the traditional 48-h reading with a single 72-h reading in future guidelines, contributing to enhanced efficiency and cost-effectiveness in clinical practice.

Allergic or Not: Final Interpretation of Doubtful Patch Test Reactions From the North American Contact Dermatitis Group, 2019-2020

Background: Doubtful patch test reactions generally do not meet criterion for positivity in patch testing. However, the North American Contact Dermatitis Group (NACDG) allows for doubtful reactions to be coded with a final determination of "allergic/positive" based on the temporal pattern, appearance, known characteristics of the allergen, and/or other supportive patch test reactions. Objectives: To analyze NACDG data from the 2019-2020 patch test cycle to identify patterns in the interpretation and relevance of doubtful reactions. Methods: The frequency and proportions of doubtful reactions were tabulated and analyzed for patterns. Statistical analyses were limited to allergens with ≥30 doubtful reactions to ensure adequate sample size. Results: Of patch-tested patients, 31.9% (1315/4121) had ≥1 doubtful reaction. Of 2538 total doubtful reactions, 46% (n = 1167) had a final interpretation of "allergic/positive." The allergens with the highest proportion of doubtful reactions at the final visit were hydroperoxides of linalool 1% (4.5%), fragrance mix I 8.0% (3.9%), and cetrimonium chloride 0.5% (3.4%). Methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) 0.02% (P < 0.001), MI 0.2% (P < 0.001), nickel sulfate hexahydrate 2.5% (P = 0.001), and neomycin sulfate 20.0% (P = 0.003) doubtful reactions were more likely to be interpreted as allergic than nonallergic. Methyldibromoglutaronitrile/phenoxyethanol 0.2% (P < 0.001), oleamidopropyl dimethylamine 0.1% (P < 0.001), formaldehyde 2.0% (P < 0.001), cetrimonium chloride 0.5% (P < 0.001), benzophenone-4 (sulisobenzone) 10% (P < 0.001), iodopropynyl butylcarbamate 0.5% (P < 0.001), cocamidopropyl betaine 1.0% (P = 0.002), and benzisothiazolinone 0.1% (P = 0.012) doubtful reactions were less likely to be interpreted as allergic. Of the 1167 doubtful reactions interpreted as allergic, 84.9% had current relevance. Conclusions: Doubtful reactions were common and approximately one half were coded with a final interpretation of "allergic/positive." Of those, most were clinically relevant. MCI/MI, MI, nickel, and neomycin were more likely to be interpreted as allergic.

A systematic review of allergic and irritant contact dermatitis of the vulva: The most important allergens/irritants and the role of patch testing

Vulvar allergic contact dermatitis (vACD) and irritant contact dermatitis (vICD) are common and accompanied by a great burden on the patient's life. We aimed to review the existing literature on vACD and vICD in order to provide a comprehensive reference list of potential vulvar allergens and irritants, as well as to establish the role of patch testing therein. A systematic search was performed in Medline, Embase and Web of Science using a search string based on the PICO-format. The study protocol was registered at PROSPERO (CRD42021239527). Multiple allergens were identified and included metals, topical drugs, fragrances, preservatives, cosmetic constituents and rubber components. Not all positive reactions were, however, considered to be relevant. Patch testing is the primary tool for the identification of the causal allergens. Testing with standard series alone was proven to be insufficient. Little information about irritants was found. In the future, additional series and late readings should be considered in standard practice. Studies on vICD are scarce and further research is necessary. More population-based research should be performed.

A Retrospective Review of Late Delayed Positive Patch Testing Greater Than Day 8 at Mayo Clinic From 2001 to 2020

BACKGROUND

Patch tests are read between days 5 and 7, because most hypersensitivity reactions occur within 7 days. Later reactions can occur after day 8, which may be missed.

OBJECTIVE

The aim of the study was to review all late delayed positive (LDP) reactions that have occurred after day 8 at Mayo Clinic from 2001 to 2020.

METHODS

Mayo Clinic records were reviewed for patients who had patch test readings performed at greater than day 8. Late delayed positive reactions were defined as any patch tests that were initially negative from days 4 to 7 yet became positive after day 8.

RESULTS

Two hundred seventy-four patients developed 439 LDPs to 89 allergens. Fourteen allergens had LDPs in at least 2% of patients: gold (gold sodium thiosulfate-3 concentrations, gold chloride, potassium dicyanoaurate), cobalt (cobalt sulfate, cobalt chloride hexahydrate), beryllium, palladium, acrylates (2-hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate), dodecyl gallate, and gentamycin. Late delayed positive reactions to gold allergens were the most frequent reactions. Up to 90% of relevant gold allergen LDPs were positive by day 15.

CONCLUSIONS

Positive patch test readings after day 8 are uncommon, but allergens most likely to be positive are metals (gold, cobalt, palladium, beryllium), acrylates, dodecyl gallate, and gentamycin. Gold allergens showed the highest LDP rates and relevance, with most reactions occurring by day 15.

Patch test results with the European baseline series, 2019/20-Joint European results of the ESSCA and the EBS working groups of the ESCD, and the GEIDAC

BACKGROUND

Continual analyses of patch test results with the European baseline series (EBS) serve both contact allergy surveillance and auditing the value of included allergens.

OBJECTIVES

To present results of current EBS patch testing, obtained in 53 departments in 13 European countries during 2019 and 2020.

METHODS

Anonymised or pseudonymised individual data and partly aggregated data on demographic/clinical characteristics and patch test rest results with the EBS were prospectively collected and centrally pooled and analysed.

RESULTS

In 2019 and 2020, 22 581 patients were patch tested with the EBS. Sensitization to nickel remained most common (19.8 [19.2-20.4]% positivity [95% confidence interval]). Fragrance mix I and Myroxylon pereirae yielded very similar results with 6.80 (6.43-7.19)% and 6.62 (6.25-7.00)% positivity, respectively. Formaldehyde at 2% aq. yielded almost one percentage point more positive reactions than 1% concentration (2.49 [2.16-2.85]% vs. 1.59 [1.33-1.88]); methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) and MI alone up to around 5% positives. Among the new additions, propolis was most commonly positive (3.48 [3.16-3.82]%), followed by 2-hydroxyethyl methacrylate (2.32 [2.0-2.68]%).

CONCLUSION

Ongoing surveillance on the prevalence of contact sensitization contributes to an up-to-date baseline series containing the most frequent and/or relevant contact sensitizers for routine patch testing in Europe.

The benefit of late readings in patch testing depends both on allergen and patient characteristics

BACKGROUND

Patch test (PT) readings are recommended after 48 h and 72 h (D3). An additional day 7 (D7) reading has been suggested by some, although data on efficient patient selection are scarce. We investigated positive D7 reactions regarding (i) allergens in the baseline series and additional PT series of the German Contact Dermatitis Research Group (DKG) and (ii) characteristics of the patients tested.

METHODS

Retrospective, multicentre analysis of 190 allergens derived from 17 DKG test series in 4687 patients with an additional D7 reading. Patients were patch tested with the baseline series and additional series, if required. Occurrence of novel D7 reactions as well as increasing skin reactions from D3 to D7 was analysed separately.

RESULTS

Depending on the allergen tested, waiving D7 readings would have missed 4.4-26.8% of positive PT results. Patch test series with the highest number of novel D7 reactions were baseline series, metal series, and leather/shoe series. New positive reactions on D7 were associated with age over 50 years and with a negative irritant control containing sodium lauryl sulphate. Of note, application of the PT allergens for 48 h instead of 24 h was positively associated with late PT reactions.

CONCLUSION

Within the most frequently tested allergens, without late readings, on average 11.7% of sensitizations would have been missed. Novel late reacting allergens were identified. This study comprehensively dissects patient-, allergen- and test-dependent parameters in support for D7 readings. We propose to always consider late readings individually based on effort-benefit considerations.

Predictive factors for Day 7 positive patch test readings at a secondary referral centre

Background

Based on studies at tertiary centres it is known that patch test reading on Day (D) 7 may show additional positive reactions. Female gender, higher age and allergen groups of topicals and corticosteroids were identified as predictive factors.

Objectives

The first aim was to study the value of reading patch tests on D2, D3 and D7 at a secondary referral centre. The second aim was to investigate the predictive potential of the factors sex, age, atopic dermatitis, body location, allergen group and clinical relevance for a positive reaction only on D7.

Methods

Retrospective data from patients tested between 2013 and 2016 were evaluated. The factors sex, age, atopic dermatitis, body location, allergen group and clinical relevance were tested by regression analysis.

Results

Two hundred and sixty-three out of a total of 396 patients had a positive reaction only on D2, D3 and D7 in 14 (2.5%), 152 (27.5%) and 61 (11.0%) occasions, observed in 10 (2.5%), 108 (27.3%) and 51 (12.9%) patients, respectively. These reactions were deemed relevant in 0 (0%), 12 (2.2%) and 9 (1.6%) occasions, observed 0 (0%), 11 (2.8%) and 9 (2.3%) patients, respectively. Higher age and allergen groups of metals, fragrances and resins were predictive for late positive reactions.

Conclusions

D7 patch test reading should also be routinely adopted at secondary referral centres. D7 positive reactions were associated with higher age and sensitization to metals, fragrances and resins.

Immunological Mechanisms of Metal Allergies and the Nickel-Specific TCR-pMHC Interface

Besides having physiological functions and general toxic effects, many metal ions can cause allergic reactions in humans. We here review the immune events involved in the mediation of metal allergies. We focus on nickel (Ni), cobalt (Co) and palladium (Pd), because these allergens are among the most prevalent sensitizers (Ni, Co) and immediate neighbors in the periodic table of the chemical elements. Co-sensitization between Ni and the other two metals is frequent while the knowledge on a possible immunological cross-reactivity using in vivo and in vitro approaches remains limited. At the center of an allergic reaction lies the capability of a metal allergen to form T cell epitopes that are recognized by specific T cell receptors (TCR). Technological advances such as activation-induced marker assays and TCR high-throughput sequencing recently provided new insights into the interaction of Ni2+ with the αβ TCR-peptide-major histocompatibility complex (pMHC) interface. Ni2+ functionally binds to the TCR gene segment TRAV9-2 or a histidine in the complementarity determining region 3 (CDR3), the main antigen binding region. Thus, we overview known, newly identified and hypothesized mechanisms of metal-specific T cell activation and discuss current knowledge on cross-reactivity.

Diagnosis and Management of Dermatitis, Including Atopic, Contact, and Hand Eczemas

This is a comprehensive and current guide for the diagnosis, differential diagnosis, treatment, and management of eczematous dermatitis, with a focus on atopic dermatitis, irritant and allergic contact dermatitis, hand dermatitis including recurrent vesicular and hyperkeratotic types, asteatotic dermatitis, and nummular or discoid dermatitis. Diagnostic options highlighted are clinical history, physical examination, and patch testing. Therapeutic options highlighted are moisturizers, topical corticosteroids, topical calcineurin inhibitors, crisaborole, phototherapy, and systemic medications including biologics.

Contact dermatitis

Contact dermatitis (CD) is among the most common inflammatory dermatological conditions and includes allergic CD, photoallergic CD, irritant CD, photoirritant CD (also called phototoxic CD) and protein CD. Occupational CD can be of any type and is the most prevalent occupational skin disease. Each CD type is characterized by different immunological mechanisms and/or requisite exposures. Clinical manifestations of CD vary widely and multiple subtypes may occur simultaneously. The diagnosis relies on clinical presentation, thorough exposure assessment and evaluation with techniques such as patch testing and skin-prick testing. Management is based on patient education, avoidance strategies of specific substances, and topical treatments; in severe or recalcitrant cases, which can negatively affect the quality of life of patients, systemic medications may be needed.

Value of photo assessment in late patch test readings-A multicenter study from six European patch test clinics

BACKGROUND

It is recommended that patch test readings include a day (D)7 reading. Substitution of the D7 reading with a photo may be a valid option.

OBJECTIVES

To compare the sensitivity of digital photos at D7 to clinical readings, to assess the number of positive reactions appearing at D7 only (late reactions), and after D7 only (delayed reactions).

METHODS

Patients patch tested in six European clinics were instructed to forward photos of the patch test reactions to the respective clinics at D7 (before attending the clinic) and at D21. Only allergens in the baseline series or TRUE Test were included in the data analysis.

RESULTS

Two hundred ninety-three of 629 patients had a total of 599 positive reactions, with 6.3% occurring at D7 only. When substituting the D7 reading with a photo (90% submitted), 26.3% of late reactions were missed and nine false-positive reactions were found. Delayed reactions were detected in four patients at D21 (65.3% submitted).

CONCLUSION

Our data show that if the D7 reading is not performed, 6.3% of positive reactions from the baseline series would be missed, and if substituting the D7 reading by digital photo, 26.3% late reactions would be missed. Delayed reactions seemed rare.

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.

Delayed patch test reaction to budesonide in an 8-year-old

Topical corticosteroids are an emerging cause of allergic contact dermatitis in children that may often be missed. It is important to consider patch testing with corticosteroids to detect allergic contact dermatitis in patients with persistent or worsening of dermatitis despite topical corticoseroid treatment. However, delayed reactions (>7 days) to topical corticosteroids may occur, leading to false-negative reactions and misdiagnosis. Herein, we report a case of an 8-year-old girl who developed a positive reaction to budesonide on day 12 of patch testing.

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.

New positive patch test reactions on day 7-The additional value of the day 7 patch test reading

BACKGROUND

Not performing a day (D) 7 patch test reading might result in positive patch test reactions being missed.

OBJECTIVES

To investigate the added value of the D7 patch test reading for individual allergens, and to identify patient characteristics and allergen groups associated with new positive D7 reactions.

METHODS

Data from patients patch tested between 2008 and 2018 with the extended European baseline series were analysed. Patch test readings were performed on D3 and D7. Positive reactions were categorized into positive on D3 or new positive on D7.

RESULTS

A total of 3292 patients were consecutively patch tested with at least 43 allergens of the TRUE Test panels 1 and 2 supplemented with investigator-loaded allergens. In total, 447 (13.6%) patients showed new positive D7 reactions. In univariable regression analysis, age between 18 and 30 years showed a negative association with new positive D7 reactions. Significantly more D7 positive reactions were seen for topicals (odds ratio [OR] 2.60, 95% confidence interval [CI]: 1.92-3.51) and corticosteroids (OR 1.87, 95%CI: 1.09-3.21). No associations were found between sex, atopic dermatitis and occupational dermatitis and a new positive D7 reaction.

CONCLUSION

A D7 reading to identify new positive patch test reactions is of added value, especially for topicals and corticosteroids.