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Background: Allergic contact dermatitis is frequently caused by metals, including multiple metals simultaneously. Objectives: To assess characteristics and associations of positive and clinically relevant patch test (PT) reactions with solitary and concurrent metal sensitization. Methods: A retrospective analysis of PT results for nickel, cobalt, and/or chromium from the North American Contact Dermatitis Group between 2001 and 2018 ( n  = 43,522). Results: 18.0% had a positive/allergic reaction to nickel sulfate hexahydrate, 7.3% to cobalt chloride hexahydrate, and 3.0% to potassium dichromate. 87.9% patients had a currently relevant reaction to 0, 9.4% to 1, and 2.7% to multiple metals tested. Patients with 1 versus no currently relevant reactions to metal were more likely to have a primary dermatitis site of trunk, feet, and ears; patients with currently relevant reactions to multiple metals had more dermatitis affecting the trunk and ears. Metal sources varied by co-reacting metal, especially for patients with cobalt and chromium allergy. Jewelry was the most commonly identified source of nickel and cobalt for both solitary and concurrent metal allergy. Conclusions: Sensitization to multiple metals occurred in 6% of patients. Allergen sources varied between patients with sensitivity to 1 metal versus those who had concurrent sensitivity to cobalt and/or chromium.

Background: Cobalt is a recognized cause of allergic contact dermatitis (ACD); however, detailed information on patient characteristics, sites, and sources is lacking. Objective: The aim of the study is to assess trends in patch test reactions to cobalt and associated patient characteristics, common sources, and body sites affected. Methods: The study used a retrospective analysis of adult patients who were patch tested to cobalt by the North American Contact Dermatitis Group between 2001 and 2018 (n = 41,730). Results: Overall, 2986 (7.2%) and 1362 (3.3%) had allergic or currently relevant patch test reaction to cobalt, respectively. Patients with versus without an allergic patch test reaction to cobalt were more likely to be female, employed, have a history of eczema or asthma, be Black, Hispanic, or Asian, and have occupational-related dermatitis. The most commonly identified sources of cobalt in allergic patients included jewelry, belts, and cement, concrete, and mortar. Affected body site(s) varied by cobalt source among patients with currently relevant reactions. Occupational relevance was found in 16.9% of patients with positive reactions. Conclusions: Positive patch test reactions to cobalt were common. The most common body sites were the hands, and affected site varied by the source of cobalt.

Background: An updated understanding of allergic contact cheilitis is needed., Objectives: To characterize clinical characteristics and allergen relevance in patients with cheilitis referred for patch testing., Methods: Retrospective analysis of 43 772 patients patch tested with the North American Contact Dermatitis Group (NACDG) screening series from 2001 to 2018., Results: Overall, 2094 patients (4.8%) had lips as one of three sites of dermatitis, 1583 (3.6%) had lips as the primary site and 1167 (2.7%) had lips as the sole site of dermatitis. Prevalences of cheilitis at any, primary, and sole sites significantly increased throughout the study cycle from 2001-2002 (2.7%, 2.2% and 1.7%) to 2017-2018 (7.8%, 5.2% and 3.7%). Approximately 60% of patients with any, a primary, or a sole site of cheilitis had one or more positive allergic patch-test reactions compared to 65% of those without cheilitis., Conclusion: Patients with cheilitis who were referred for patch testing had high rates of positive and relevant allergens. More than one in four patients with any, primary, or sole cheilitis had a positive reaction to non-NACDG screening allergens (28.0%, 26.8%, 31.1% vs. 21.6%) compared to patients without cheilitis, emphasizing the need for expanded patch test series in cheilitis., (© 2022 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Patch testing is an important diagnostic tool for assessment of allergic contact dermatitis (ACD). Objective: This study documents the North American Contact Dermatitis Group (NACDG) patch testing results from January 1, 2019, to December 31, 2020. Methods: At 13 centers in North America, patients were tested in a standardized manner with a screening series of 80 allergens, and, as indicated, supplemental allergens. Results: Overall, 4121 patients were tested; 2871 (69.7%) had at least 1 positive/allergic patch test reaction and 2095 patients (51.2%) had a primary diagnosis of ACD. The most commonly positive allergens were nickel (18.2%), methylisothiazolinone (MI) (13.8%), fragrance mix (FM) I (12.8%), hydroperoxides of linalool (HPL) (11.1%), and benzisothiazolinone (BIT) (10.4%). Compared with that of 2017-2018, prevalence of top 20 allergens statistically increased for FM I, HPL, BIT, propolis, and hydroperoxides of limonene (3.5%). For the first time, MI positivity did not increase between reporting periods. Approximately one-fifth of patients (20.3%) had ≥1 clinically relevant reaction(s) to allergens/substances not on the NACDG series. Conclusions: The epidemic of MI contact allergy in North America may have reached a plateau. Patch testing using a robust screening series, and supplemental allergens as indicated, is necessary for comprehensive evaluation of ACD.

Background: Few studies explored the relationship between stasis dermatitis (SD) and allergic contact dermatitis (ACD)., Objective: To examine trends, associations, and clinical relevance of ACD in patients referred for patch testing who had a final SD diagnosis., Methods: Retrospective analysis from 2001 to 2016 of 38,723 patients from the North American Contact Dermatitis Group., Results: After patch testing, 303 (0.7%) patients were diagnosed with SD; 46.7% had a concomitant diagnosis of ACD. Patients with vs. without a final SD diagnosis had similar proportions of ≥ 1 positive allergic reaction (59.7% vs. 64.7%; Chi-square, P = 0.0724) but higher odds of allergic reactions to fragrance mix I, bacitracin, quaternium-15, Myroxylon pereirae, benzalkonium chloride, ethyleneurea melamine formaldehyde, diazolidinyl urea, and propylene glycol. The most commonly relevant allergens in patients with final SD diagnosis were fragrance mix I, Myroxylon pereirae, bacitracin, quaternium-15, and formaldehyde. The most common allergen sources were personal care products, topical medications and other health aid products., Conclusion: Nearly half of patients with a final SD diagnosis were also diagnosed with ACD, supporting the role of patch testing in select SD patients., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Dermatitis localized to hands (HD), feet (FD), or both hands and feet (HFD) has multiple etiologies, including atopic dermatitis, irritant contact dermatitis, and allergic contact dermatitis. Unfortunately, little is known about clinical differences between patients with HD, FD, and HFD., Objective: To characterize differences in demographics, etiology, and patch testing results among patients presenting with HD, FD, or HFD referred for patch testing., Methods: A retrospective analysis of patients patch tested by the North American Contact Dermatitis Group between 2001 and 2018., Results: Of 43,677 patients who were patch tested, 22.8% had HD, 2.9% had FD, and 3.7% had HFD. Allergic and currently relevant patch test reactions to ≥1 North American Contact Dermatitis Group screening allergen occurred in similar proportions in all 3 study groups. However, HD (18.0%) had higher proportions of occupationally relevant reactions than HFD (8.9%) or FD (4.0%). Nickel and fragrance mix I were in the top 5 currently relevant allergens for HD, FD, and HFD. Other top allergens, as well as allergen sources, differed between HD, FD, and HFD., Limitations: No data on HD or FD morphology or distribution., Conclusion: HD, FD, and HFD have several differences with respect to patient characteristics, etiologies, and clinically relevant allergens., Competing Interests: Conflicts of interest Drs Sasseville and Reeder receive royalties from UpToDate (Wolters Kluwer Health). Dr Taylor owns noncontrolling common stock in Cigna, Merck, Johnson & Johnson, Astra Zeneca, and Opko Health is a member of the Cosmetic Ingredient Review Steering Committee and a nondependent child is employed by Pfizer. Dr Warshaw has served as a consultant for Wen by Chaz Dean and Noven Pharmaceuticals and a grant funded by Wen by Chaz Dean. Dr Atwater has received the Pfizer Independent Grant for Learning & Change and has consulted for Henkel. She is employed by Eli Lilly and Company. Drs Silverberg, DeKoven, Belsito, Houle, Zug, DeLeo, Pratt, Fowler, Maibach, and author Patel have no conflicts of interest to declare., (Copyright © 2022 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Ammonium persulfate (APS), an oxidizing agent used in hair products, manufacturing, and pool/spa water, can cause skin reactions, including allergic contact dermatitis., Objective: To characterize positive patch test reactions to APS (2.5% petrolatum)., Methods: Retrospective analysis of patients tested to the North American Contact Dermatitis Group screening series from 2015 to 2018., Results: Of 10,526 patients, 193 (1.8%) had positive patch test reactions to APS. Compared with APS-negative patients, APS-positive patients were significantly more likely to be male (43.2% vs 28.0%; P < .0001); have primary hand dermatitis (30.2% vs 22.0%; P = .0064), scattered generalized dermatitis (25.5% vs 17.9%; P = .0064), or trunk dermatitis (8.9% vs 4.9%; P = .0123); and have dermatitis that is occupationally related (22.2% vs 10.9%; P < .0001). More than half of the APS-positive reactions were currently relevant (57.0%); 19 (9.8%) were related to occupation, especially hairdressers (68.4%). Swimming pools/spas (23.3%) and hair care products (19.2%) were the most common sources of APS., Limitations: Immediate reactions and follow-up testing were not captured., Conclusion: The proportion of patients positive to APS was 1.8%. APS positivity was significantly associated with male sex and hand dermatitis. Swimming pool/spa chemicals were important sources of APS exposure., Competing Interests: Conflicts of interest Dr Atwater received a Pfizer Independent Grant for Learning & Change and has consulted for Henkel. Dr Warshaw has received research funding from Wen by Chaz Dean and served as a consultant for Noven Pharmaceuticals and Wen by Chaz Dean. Dr Taylor owns shares of stock in Astra Zeneca, Cigna, Merck, Johnson & Johnson, and Opko Health; has consulted for Kao Brands and Monsanto (Bayer); is a member of the Cosmetic Ingredient Review Steering Committee; and has a nondependent child employed by Pfizer. Dr Sasseville receives royalties from UpToDate (Wolters Kluwer Health). Drs DeKoven, Pratt, Silverberg, Maibach, Zug, Reeder, Fowler, Fransway, Belsito, DeLeo, Houle, and Dunnick and Ms Ruggiero have no conflicts of interest to declare., (Copyright © 2021 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Alkyl glucosides are nonionic surfactants that are increasingly used in personal care products., Objective: To characterize positive patch test reactions to decyl glucoside (5% petrolatum, tested 2009-2018) and lauryl glucoside (3% petrolatum, tested 2017-2018)., Methods: Retrospective analysis of patients tested by the North American Contact Dermatitis Group., Results: Of 24,097 patients patch tested to decyl and/or lauryl glucoside, 470 (2.0%) had positive reactions. Compared with glucoside-negative patients, glucoside-positive patients had higher odds of occupational skin disease (13.4% vs 10.1%; P = .0207), history of hay fever (38.5% vs 31.6%; P = .0014), atopic dermatitis (39.0% vs 28.6%; P < .0001), and/or asthma (21.8% vs 16.5%; P = .0023). Most glucoside reactions (83.9%) were currently relevant. The most common source was personal care products (63.0%), especially hair products (16.5%) and skin cleansers (15.2%). Of 4933 patients tested to decyl and lauryl glucoside, 134 (2.7%) were positive to 1 or both; 43.4% (43 of 99) of decyl-positive patients were also positive to lauryl glucoside and 55.1% (43/78) of lauryl glucoside patients were also positive to decyl glucoside., Limitations: The cohort predominantly reflects a referral population, and follow-up after testing was not captured., Conclusion: Glucoside positivity occurred in 2.0% of the tested patients. Reactions were often clinically relevant and linked to personal care products. Cross-reactivity was >40%., Competing Interests: Conflicts of interest Dr Warshaw reports investigator-initiated grant from WEN by Chaz Dean and has served as a consultant for WEN by Chaz Dean and Noven Pharmaceuticals. Dr Atwater has received a Pfizer Independent Grant for Learning & Change, has consulted for Henkel, and is employed by Eli Lilly and Company. Dr Taylor owns noncontrolling common shares of stock in Astra Zeneca, Cigna, Merck, Johnson & Johnson, and Opko Health; has consulted for Kao Brands and Monsanto (Bayer); is a member of the Cosmetic Ingredient Review Steering Committee; and has a nondependent child employed by Pfizer. Dr Sasseville receives royalties from UpToDate (Wolters Kluwer Health). Author Xiong and Drs DeKoven, Pratt, Maibach, Belsito, Silverberg, Reeder, Zug, Fowler, DeLeo, Houle, and Dunnick have no conflicts of interest to disclose., (Copyright © 2022 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Allergic contact dermatitis (ACD) to cobalt is more common in children and adolescents than adults. However, detailed information on sites and sources of cobalt ACD is limited., Objectives: To assess trends in positive and clinically relevant patch test reactions to cobalt in children and associated patient characteristics, common sources and body sites affected., Methods: A retrospective analysis of children (<18 years) patch tested to cobalt by the North American Contact Dermatitis Group between 2001 and 2018., Results: Of 1919 children patch tested, 228 (11.9%) and 127 (6.6%) had a positive/allergic or currently relevant patch test reaction to cobalt, respectively. The most common primary body sites affected were scattered generalized (30.0%), face, not otherwise specified (10.6%) and trunk (10.1%). Patients with allergic and currently relevant allergic patch test reactions were more likely to have a primary site of trunk (p = 0.0160 and p = 0.0008) and ears (p = 0.0005 and p < 0.0001). Affected body site(s) varied by cobalt source among patients with currently relevant reactions, especially for less common sources. The most commonly identified sources of cobalt included jewellery, belts and clothing., Conclusions: Positive patch test reactions to cobalt were common in children. The most common body site was scattered generalized and the sources of cobalt varied by body site., (© 2022 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Identification of allergens causing medical adhesive contact allergy is difficult., Objective: To characterize the demographics, clinical characteristics, patch test results, and occupational data for North American Contact Dermatitis Group patients with medical adhesive contact allergy., Methods: A retrospective study of 43,722 North American Contact Dermatitis Group patients patch tested from 2001 to 2018 with medical adhesive (tapes/bandaids/adhesive aids/suture glue) sources, positive patch test results, and final primary diagnoses of allergic contact dermatitis., Results: In total, 313 (0.7%) patients met the inclusion criteria. Compared with other patients with final primary diagnoses of allergic contact dermatitis, patients with a medical adhesive allergy were less likely to be male (odds ratio, 0.58; 95% CI, 0.45-0.77) and/or aged >40 years (odds ratio, 0.76; 95% CI, 0.60-0.96). The most common North American Contact Dermatitis Group screening series allergens were colophony (80.7%), balsam of Peru (3.9%), 2-hydroxyethyl methacrylate (2.7%), and carba mix (2.7%). One-fourth of the patients (79/313, 25.2%) had positive patch test reactions to supplemental allergens/materials, and 54 (17.3%) of the 313 patients only had reactions to supplemental allergens/materials., Limitations: Results of comprehensive patch testing may be prone to referral population selection bias and may not be representative of the general dermatology population., Conclusion: Colophony was the most common allergen. Supplemental allergens and materials should be tested in the evaluation of a suspected medical adhesive contact allergy., Competing Interests: Conflicts of interest Dr Taylor has consulted for Johnson & Johnson, Bayer, Kao Brands, and Equinox Group; received royalties from Decision Support in Medicine; owns noncontrolling shares of common stock in AstraZeneca, Cigna, Johnson & Johnson, Merck, and Opko Health; and is a member of the Steering Committee of the Cosmetic Ingredient Review; a nondependent child is an employee of Pfizer. Dr Reeder is the American Contact Dermatitis Society Contact Allergy Management Program Director. Drs Sasseville and Reeder receive royalties from UpToDate (Wolters Kluwer Health). Dr Atwater received the Pfizer Independent Grant for Learning & Change, has consulted for Henkel, and is currently employed by Eli Lilly and Company. Dr Warshaw has received an investigator-initiated grant from and served as a consultant for Wen by Chaz Dean and served as a consultant for Noven Pharmaceuticals. Drs Bembry, Liu, DeKoven, Silverberg, Zug, Houle, Belsito, Maibach, Dunnick, Fowler, Pratt, and DeLeo have no conflicts of interest to declare., (Copyright © 2021 American Academy of Dermatology, Inc. All rights reserved.)

Competing Interests: C.R.H. is the son of Curt Hamann, CEO of SmartPractice, a company that manufactures and sells patch testing materials. The other authors have no funding or conflicts of interest to declare.

Competing Interests: C.R.H. is the son of Curt Hamann, owner and chief executive officer of SmartPractice, a company that produces diagnostic patch test materials. The other authors have no funding or conflicts of interest to declare.

Background: Lanolin is an important cause of allergic contact dermatitis., Objectives: The aims of this study were to describe the epidemiology of lanolin allergy and to assess trends in patch test reactions to lanolin over time., Methods: This study used a retrospective analysis of patients patch tested with lanolin alcohol 30% or Amerchol L-101 50% in petrolatum by the North American Contact Dermatitis Group between 2001 and 2018 (n = 43,691)., Results: Overall, 1431 (3.3%) had a positive reaction, and 1238 (2.8%) were currently relevant. Prevalence of lanolin allergy was 4.63% between 2011 and 2018 (P < 0.0001). Most lanolin-allergic patients had + (52%) reactions; 18%, and 6% had ++ and +++ reactions, respectively. Common primary anatomic sites of dermatitis were the hands (20.7%), scattered/generalized distribution (19.6%), and face (17.0%). Allergic reactions to lanolin were more common in children (4.5%) than in adults (3.2%, P = 0.0018). Compared with nonallergic patients, lanolin-allergic patients were more likely to have history of eczema or hay fever, male sex, older than 40 years, or Black race (P < 0.05). Common lanolin sources were personal care products and drugs/medications. Only 2.24% of the positive reactions were linked to occupation., Conclusions: Lanolin sensitivity was common. Reactions were often clinically relevant and linked to personal care products and medications., Competing Interests: D.S. receives royalties from UpToDate (Wolters Kluwer Health). J.S.T. owns noncontrolling common stock in Cigna, Merck, Johnson and Johnson, AstraZeneca, and Opko Health and is a member of the Cosmetic Ingredient Review Steering Committee; a nondependent child is employed by Pfizer. E.M.W. has served as a consultant for Wen by Chaz Dean and Noven Pharmaceuticals, as well as a grant funded by Wen by Chaz Dean. A.R.A. received the Pfizer Independent Grant for Learning & Change and has consulted for Henkel. She is employed by Eli Lilly and Company. The remaining authors have no funding or conflicts of interest to declare., (Copyright © 2022 American Contact Dermatitis Society. All Rights Reserved.)

Background: An updated understanding of allergic contact dermatitis is needed, particularly in children., Objectives: To compare positive and clinically relevant reactions in children versus adults referred for patch testing., Methods: Retrospective analysis of 1871 children and 41,699 adults from the North American Contact Dermatitis Group (NACDG) from 2001-2018., Results: Both final diagnosis of allergic contact dermatitis (55.2% versus 57.3%; chi square, P = .0716) and prevalence of ≥ 1 currently relevant reaction to a NACDG screening allergen (49.2% vs 52.2%; P = .1178) were similar between children and adults. Currently in children, the most common relevant allergens were nickel sulfate (17.3%), hydroperoxides of linalool (7.8%), methylisothiazolinone (7.7%), cobalt chloride (7.0%), and fragrance mix I (4.9%). Approximately a fifth of children had a positive reaction to a non-NACDG allergen., Conclusion: Over half of children referred for patch testing were diagnosed with allergic contact dermatitis. The most common relevant allergens in children were nickel sulfate, cobalt chloride, and hydroperoxides of linalool. Twenty percent of children had at least 1 positive reaction to allergens/substances not on the NACDG screening series, underscoring the need for comprehensive testing., Competing Interests: Conflicts of interest This study was supported by resources and use of facilities at the Minneapolis Veterans Affairs Medical Center. The contents do not represent the views of the US Department of Veterans Affairs or the US Government. Dr Sasseville receives royalties from UpToDate (Wolters Kluwer Health). Dr Taylor owns noncontrolling common stock in Cigna, Merck, Johnson and Johnson, Astra Zeneca, and Opko Health; is a member of the Cosmetic Ingredient Review Steering Committee; and has a nondependent child who is employed by Pfizer. Dr Warshaw has served as a consultant for Wen by Chaz Dean and Noven Pharmaceuticals and is grant funded by Wen by Chaz Dean. Dr Atwater received a Pfizer Independent Grant for Learning & Change and has consulted for Henkel., (Copyright © 2021 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Patch testing is an important diagnostic tool for suspected allergic contact dermatitis (ACD) in occupational settings., Objective: Provide an overview of occupational skin disease (OSD) and an analysis of occupational ACD in North American patients undergoing patch testing between 2001and 2016., Methods: Patients with OSD were analyzed for frequency of allergic reactions to a screening series of allergens, occupational relevance, location of skin disease, and exposure sources. Demographic, occupation, and industry information were recorded., Results: Of 38,614 patients evaluated, 4471 (11.6%) had OSD, of whom 3150 (70.5%) had ACD. The most common occupationally related allergens included rubber accelerators, preservatives, and bisphenol A epoxy resin. Hands (75.8%), arms (30.0%), and face (15.9%) were common sites of dermatitis. The occupations most affected were service workers and machine operators., Limitations: Our cohort may not reflect the general working population., Conclusion: This study identified common occupational allergens, exposure sources, and occupations/industries at risk. This information may help the clinician evaluate and manage patients with occupational contact dermatitis., Competing Interests: Conflicts of interest Dr Warshaw has received an investigator-initiated grant from Wen by Chaz Dean and served as a consultant for Wen by Chaz Dean and Noven Pharmaceuticals. Dr Atwater received a Pfizer Independent Grant for Learning & Change and has consulted for Henkel. Dr Sasseville receives royalties from UpToDate (Wolters Kluwer Health). Dr Taylor owns non-controlling shares of stock in AstraZeneca, Cigna, Merck, Johnson & Johnson, and Opko Health and he has consulted for Kao Brands and Monsanto (Bayer), is a member of the Cosmetic Ingredient Review Steering Committee, and has a nondependent child employed by Pfizer. Drs J DeKoven, Mathias, Belsito, Fowler, Pratt, Zug, Maibach, DeLeo, Silverberg, Reeder, and Holness, and Author B DeKoven have no conflicts of interest to declare., (Copyright © 2021 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

Background/objectives: Topical medications may lead to allergic contact dermatitis. This study characterized positive patch test reactions associated with medications in patients evaluated by the North American Contact Dermatitis Group (NACDG)., Methods: This study is a retrospective analysis of the NACDG data (2001-2018). Patients with at least 1 positive patch test reaction associated with a medication source were included. Allergens, reaction characteristics, clinical relevance, and source details were tabulated., Results: Of 43,722 patients, 6374 (14.6%) had positive allergic patch test reactions associated with 1 or more topical medication sources. Patients with versus without allergic reactions to medications were more likely to be older than 40 years (P < 0.0001) and/or have primary sites of dermatitis on the legs, anal/genital region, or trunk (P < 0.0001). There were 8787 reactions to NACDG allergens; the most common were neomycin (29.4%), bacitracin (29.1%), propylene glycol 100% (10.6%), tixocortol-17-pivalate (10.0%), lidocaine (7.9%), budesonide (4.9%), and dibucaine (4.4%). Propylene glycol 100% was the most common inactive ingredient (10.6%). Current relevance was present in 61.0%. A total of 6.5% of the individuals with medication allergy would have had 1 or more positive patch test reactions missed if only tested to the NACDG screening series., Conclusions: Positive patch test reactions associated with topical medications were common (14.6%), and most were clinically relevant. Patients with topical medication allergy were twice as likely to have anal/genital involvement. Active ingredients, especially neomycin, bacitracin, and tixocortol-17-pivalate, were frequent culprits., Competing Interests: A.R.A. received a Pfizer Independent Grant for Learning & Change and has consulted for Henkel. J.S.T. owns noncontrolling common shares of stock in AstraZeneca, Cigna, Merck, Johnson & Johnson, and Opko Health. He has consulted for Kao Brands and Monsanto (Bayer), is a member of the Cosmetic Ingredient Review Steering Committee, and has a nondependent child employed by Pfizer. E.M.W. has received an investigator-initiated grant from and served as a consultant for Wen by Chaz Dean. She has also served as a consultant to Noven Pharmaceuticals. D.S. receives royalties from UpToDate (Wolters Kluwer Health). The other authors have no funding or conflicts of interest to declare., (Copyright © 2021 American Contact Dermatitis Society. All Rights Reserved.)

Background: Shoe contact allergy can be difficult to diagnose and manage., Objective: The aim of the study was to characterize demographics, clinical characteristics, patch test results, and occupational data for the North American Contact Dermatitis Group patients with shoe contact allergy., Methods: This is a retrospective study of 33,661 patients, patch tested from 2005 to 2018, with a shoe source, foot as 1 of 3 sites of dermatitis, and final primary diagnosis of allergic contact dermatitis., Results: Three hundred fifty-two patients met the inclusion criteria. They were more likely to be male (odds ratio = 3.36, confidence interval = 2.71-4.17) and less likely to be older than 40 years (odds ratio = 0.49, confidence interval = 0.40-0.61) compared with others with positive patch test reactions. The most common relevant North American Contact Dermatitis Group screening allergens were potassium dichromate (29.8%), p-tert-butylphenol formaldehyde resin (20.1%), thiuram mix (13.3%), mixed dialkyl thioureas (12.6%), and carba mix (12%). A total of 29.8% (105/352) had positive patch test reactions to supplemental allergens, and 12.2% (43/352) only had reactions to supplemental allergens., Conclusions: Shoe contact allergy was more common in younger and male patients. Potassium dichromate and p-tert-butylphenol formaldehyde resin were the top shoe allergens. Testing supplemental allergens, personal care products, and shoe components should be part of a comprehensive evaluation of suspected shoe contact allergy., Competing Interests: J.S.T. has consulted for Johnson & Johnson, Bayer, Kao Brands, and Equinox Group; received royalties from Decision Support in Medicine; and owns noncontrolling shares of common stock in AstraZeneca, Cigna, Johnson & Johnson, Merck, and Opko Health; a nondependent child is an employee of Pfizer. He is a member of the Steering Committee of the Cosmetic Ingredient Review. M.J.R. is the American Contact Dermatitis Society Contact Allergy Management Program Director. D.S. receives royalties from UpToDate (Wolters Kluwer Health). A.R.A. received the Pfizer Independent Grant for Learning & Change and has consulted for Henkel. E.M.W. has received an investigator-initiated grant from and served as a consultant for Wen by Chaz Dean. She has also served as a consultant for Noven Pharmaceuticals. The other authors have no funding or conflicts of interest to declare., (Copyright © 2021 American Contact Dermatitis Society. All Rights Reserved.)

Background/objectives: Carvone, a flavoring agent, may cause allergic contact dermatitis. This study summarizes patch test reactions to carvone in patients tested by the North American Contact Dermatitis Group, 2009 to 2018., Methods: This was a retrospective analysis of patients positive to carvone (5% petrolatum). Demographics were compared with those of patients who were negative. Other analyses included reaction strength, clinical relevance, coreactivity with other fragrance/flavor allergens, and exposure sources., Results: Of 24,124 patients tested to carvone, 188 (0.78%) were positive. As compared with carvone-negative patients, carvone-positive patients were significantly more likely older than 40 years (P = 0.0284). Women (76.1%) and/or facial involvement (33.0%) were common in the carvone-positive group but not statistically different from carvone-negative patients; 73.3% (n = 138) of the reactions were currently relevant. Relevant sources were personal care products (46.3%, n = 87) and food (14.3%, n = 27). Coreactivity with other fragrance/flavor markers was present in 60.6% of carvone-positive patients, most commonly fragrance mix I (34.6%), balsam of Peru (24.5%), and cinnamic aldehyde (15.4%)., Conclusions: Ten-year prevalence of carvone sensitivity was 0.78%. Most carvone-positive patients were female, were older than 40 years, and/or had facial dermatitis. Personal care products were the most common source. Two-fifths of carvone reactions would have been missed by relying on other fragrance/flavoring allergens., (Copyright © 2021 American Contact Dermatitis Society. All Rights Reserved.)

Background: Ethylhexylglycerin (EHG) is a recently recognized contact allergen., Objective: The aims of the study were to characterize individuals with positive patch test reactions to EHG and to analyze reaction strength, clinical relevance, and allergen sources., Methods: This study was a retrospective analysis of the patients patch tested to EHG (5% petrolatum) by the North American Contact Dermatitis Group (2013-2018)., Results: Of 15,560 patients tested to EHG, 39 (0.25%) had positive (final interpretation of "allergic") reactions. Most were female (71.8%) and/or older than 40 years (76.9%). There were no statistically significant differences between age, sex, or atopic history when compared with EHG-negative patients. The most common anatomic sites of dermatitis were the face (28.2%) and scattered generalized distribution (25.6%). Most EHG-positive reactions were + (35.9%) or ++ (33.3%). Current clinical relevance was high (79.5%); none, however, were related to occupation. Personal care products were the most common source of exposure to EHG (59.0%)., Conclusions: Ethylhexylglycerin is a rare contact allergen; the positive frequency of 0.25% is similar to other low allergenic preservatives including parabens, benzyl alcohol, and phenoxyethanol. The patch test concentration of 5.0% seems to be nonirritating. Although relatively uncommon, EHG reactions were usually clinically relevant (79.5%), often because of moisturizers/lotions/creams., Competing Interests: A.R.A. received a Pfizer Independent Grant for Learning and Change and has consulted for Henkel. J.S.T. owns shares of stock in AstraZeneca, Cigna, Merck, Johnson & Johnson, and OPKO Health. He has consulted for Kao Brands and Monsanto (Bayer), is a member of the Cosmetic Ingredient Review Steering Committee, and has a nondependent child employed by Pfizer. E.M.W. has received an investigator-initiated grant from and served as a consultant for WEN by Chaz Dean. D.S. receives royalties from UpToDate (Wolters Kluwer Health). The other authors have no funding or conflicts of interest., (Copyright © 2021 American Contact Dermatitis Society. All Rights Reserved.)

Background: Hair care products (HCPs) may cause both allergic contact dermatitis (ACD) and irritant contact dermatitis (ICD)., Objectives: The aims of the study were to determine the prevalence of HCP-associated ICD/ACD and to characterize relevant allergens., Methods: This study is a retrospective analysis of North American Contact Dermatitis Group (NACDG) patch test data, 2001-2016., Results: Of 38,775 patients tested, 3481 (9.0%) had positive patch test reactions associated with HCPs. The HCP-positive patients were significantly more likely to be female (79.9% vs 66.0%) and/or have primary sites of dermatitis on the face (32.0% vs 27.8%) or scalp (15.4% vs 2.2%) compared with the HCP-negative patients (P < 0.0001). Of 4908 HCP-associated positive patch test reactions, 86.9% (n = 4263) were due to allergens on the NACDG screening series; p-phenylenediamine (35.8%), methylisothiazolinone (9.7%), methylchloroisothiazolinone/methylisothiazolinone (8.7%), and cocamidopropyl betaine (5.9%) were the most frequent. Most reactions (87.7%, 3736/4263) were currently clinically relevant. The most common job associated with 366 occupationally related NACDG HCP-associated allergens was hairdresser/cosmetologist (71.9%). Two hundred eighty-two patients (0.7%) had ICD associated with HCPs. Shampoo/conditioners were the most frequent source of NACDG HCP-associated reactions (47.3%) and HCP-associated ICD (45.0%)., Conclusions: Of the HCP-positive patients, 18.5% had HCP reactions to allergens not on the NACDG screening series, underscoring the importance of patch testing to expanded series in patients suspected of HCP allergy., Competing Interests: A.R.A. received a Pfizer Independent Grant for Learning & Change and has consulted for Henkel. E.M.W. has received research funding from WEN by Chaz Dean. She has also served as a consultant for Noven Pharmaceuticals, Inc, and WEN by Chaz Dean. J.S.T. owns shares of stock in AstraZeneca, Cigna, Merck, Johnson & Johnson, and OPKO Health. He has consulted for Kao Brands and Monsanto (Bayer), is a member of the Cosmetic Ingredient Review Steering Committee, and has a nondependent child employed by Pfizer. Sasseville receives royalties from UpToDate (Wolters Kluwer Health). The other authors have no funding or conflicts of interest to declare., (Copyright © 2021 American Contact Dermatitis Society. All Rights Reserved.)

Background: Dental personnel are at risk of developing occupational contact dermatitis., Objectives: The aims of the study were to determine prevalence of occupational contact dermatitis in dental personnel referred for patch testing and to characterize relevant allergens and sources., Methods: The study used a retrospective, cross-sectional analysis of the North American Contact Dermatitis Group (NACDG) data, 2001-2018., Results: Of 41,109 patients, 585 (1.4%) were dental personnel. Dental personnel were significantly more likely than nondental personnel to be female (75.7% vs 67.4%, P < 0.0001), have occupationally related dermatitis (35.7% vs 11.5%, P < 0.0001), and/or have primary hand involvement (48.6% vs 22.5%, P < 0.0001). More than one quarter of dental personnel (62/585, 27.7%) had 1 or more occupationally related allergic patch test reaction(s). There were 249 occupationally related reactions to NACDG screening allergens, most commonly glutaraldehyde (18.1%), thiuram mix (16.1%), and carba mix (14.1%). The most common sources of NACDG screening allergens were gloves (30.7%), dental materials (26.6%), and sterilizing solutions (13.1%). Seventy-three dental personnel (12.5%) had 1 or more positive patch test reactions to occupationally related allergen(s)/substances not on the screening series. Occupationally related irritant contact dermatitis was identified in 22.2% (n = 130) of dental personnel, most commonly to nonskin soaps/detergents/disinfectants (32.0%)., Conclusions: Occupational contact dermatitis is common in dental personnel referred for patch testing. Comprehensive testing beyond screening series is important in these patients., Competing Interests: A.R.A. received a Pfizer Independent Grant for Learning & Change and has consulted for Henkel. E.M.W. has received research funding from Wen by Chaz Dean. She has also served as a consultant for Noven Pharmaceuticals and Wen by Chaz Dean. J.S.T. owns shares of stock in AstraZeneca, Cigna, Merck, Johnson & Johnson, and Opko Health. He has consulted for Kao Brands and Monsanto (Bayer), is a member of the Cosmetic Ingredient Review Steering Committee, and has a nondependent child employed by Pfizer. D.S. receives royalties from UpToDate (Wolters Kluwer Health). The other authors have no funding or conflicts of interest to declare., (Copyright © 2021 American Contact Dermatitis Society. All Rights Reserved.)

Importance: Patch test screening series for patients with dermatitis are limited and may miss clinically relevant contact allergens., Objective: To characterize individuals with dermatitis who showed clinically relevant patch test findings to supplemental (nonscreening) allergens or substances., Design, Setting, and Participants: A 17-year, retrospective cross-sectional analysis (January 1, 2001, to December 31, 2018) of North American Contact Dermatitis Group (NACDG) data from multiple centers in North America was conducted. A total of 43 417 patients with dermatitis underwent patch testing to the NACDG screening series in a standardized manner with 65 to 70 allergens and supplemental allergens as clinically indicated. Patients with 1 or more clinically relevant reactions to a supplemental (nonscreening) allergen/substance were analyzed between November 18, 2020, and March 12, 2021., Main Outcomes and Measures: The main outcomes were to assess the number of patients with clinically relevant reactions to supplemental (nonscreening) allergens and compare characteristics (including demographic characteristics and occupations) between patients with a clinically relevant patch test reaction to 1 or more supplemental allergens or substances (supplement-positive) and those without a reaction (supplement-negative) using odds ratios (ORs) and 95% CIs. Secondary outcomes included sources of allergic contact dermatitis and, for occupationally related cases, specific occupations and industries., Results: Of 43 417 patients included in the study who underwent patch testing to the NACDG screening series (65-70 allergens), 9507 individuals (21.9%) had currently relevant reactions to 1 or more supplemental allergens or substances. Of these, 6608 were women (69.5%) and the mean (SD) age was 47.2 (0.54) years. Compared with patients who had supplement-negative results, patients with supplement-positive findings were significantly less likely to be male (OR, 0.90; 95% CI, 0.85-0.94; P < .001) and/or have atopic dermatitis (OR, 0.89; 95% CI, 0.84-0.93; P < .001). Common primary sites of dermatitis in 9499 patients with supplement-positive findings included the face (2856 [30.1%]), hands (2029 [21.4%]), and scattered/generalized distribution (1645 [17.3%]). Frequent sources of supplemental allergens in 9235 patients included personal care products (4746 [51.4%]) and clothing/wearing apparel (1674 [18.1%]). Of 9362 patients with available data, supplemental allergens/substances were occupationally related in 1580 (16.9%); of those with identified occupations, 25.1% (384 of 1529) were precision production, craft, or repair workers. Of 9507 patients with supplement-positive findings, 2447 (25.7%) had no currently relevant reactions to NACDG screening allergens., Conclusions and Relevance: This cross-sectional study found that 21.9% of patients who underwent patch testing to an allergen screening series of 65 to 70 allergens had at least 1 relevant reaction to supplemental allergens/substances. Of these, one-quarter reacted only to a supplemental allergen/substance. Screening series include common, important allergens, but these findings suggest that the addition of specialty allergens and personal or work products is critical for the successful diagnosis and management of allergic contact dermatitis.

Background: Personal care products (PCPs) are commonly responsible for allergic contact dermatitis and irritant contact dermatitis. PCP use was historically associated with females, but male-targeted PCPs are increasingly being marketed., Objective: To characterize and compare males with PCP-related contact dermatitis (MPCPs) and females with PCP-related contact dermatitis (FPCPs)., Methods: This was a retrospective cross-sectional analysis of North American Contact Dermatitis Group data (1996-2016)., Results: Four thousand six hundred eighty of 16,233 men (28.8%) and 12,730 of 32,222 (39.5%) women had a PCP identified as a source of irritant contact dermatitis or a positive patch test reaction. The proportion of PCP-related dermatitis in both sexes significantly increased (>2.7-fold) over the decade of study. Compared with FPCPs, a larger proportion of MPCPs were older or had trunk or extremity dermatitis (P < .0001). MPCPs were twice as likely to have soaps as a source while FPCPs were twice as likely to have hair care products (P < .0001). The most common PCP-related North American Contact Dermatitis Group allergens for both sexes were methylisothiazolinone (MPCP 28.8% and FPCP 21.5%), fragrance mix I (MPCP 22.3% and FPCP 20.1%), balsam of Peru (MPCP 18.5% and FPCP 14.1%), quaternium-15 (MPCP 16.1% and FPCP 12.3%), and paraphenylenediamine (MPCP 11.5% and FPCP 11.1%)., Limitations: Patient population referred for suspected contact dermatitis., Conclusions: PCP-related dermatitis is increasing. Sites of involvement and relevant PCP sources are distinct between sexes. Male and female variation in exposure history may explain differences in reactivity to some allergen groups., (Published by Elsevier Inc.)

Background: Contact dermatitis to homemade slime has been frequently reported, with isothiazolinones as a likely sensitizer. Little is known on the presence of these preservatives in commercial, store-bought slime products., Objectives: The aims of the study were to review the literature on "slime dermatitis" and to assess for the presence of isothiazolinones in commercially available slime products and homemade slime components., Methods: An experimental, colorimetric spot test was used to verify the presence of isothiazolinones in 38 slime products of the 16 best-selling commercial slime kits, 1 finished homemade slime, and 4 common components of homemade slime. High-performance liquid chromatography with UV detection was performed on 8 commercial slime products., Results: According to the spot test, 27 (71%) of the 38 commercial slime products contained isothiazolinones. High-performance liquid chromatography with UV detection analyses indicated, however, that false-positives and false-negatives readily occur: isothiazolinone content was correctly identified in only 4 (50%) of the 8 samples., Conclusions: This study is the first to demonstrate the presence of isothiazolinones in commercial slime toys. Although the colorimetric spot test may have some utility as a screening assay, it is far from specific and likely not sensitive enough to reliably identify methylisothiazolinone., Competing Interests: C.R.H. is the son of Curt Hamann, owner and CEO of SmartPractice, a company that produces diagnostic patch test materials. The other authors have no funding or conflicts of interest to declare., (Copyright © 2021 American Contact Dermatitis Society. All Rights Reserved.)

Objective: The aim of the study was to describe the differences in contact allergy between the United States (US) and Canada., Methods: This is a retrospective cross-sectional analysis of the North American Contact Dermatitis Group data from 2005 to 2016. Frequencies of demographics, clinical characteristics, positive reactions, trends, and occupations were calculated., Results: A total of 28,640 patients underwent patch testing. At least 1 positive patch test was observed in 18,599 patients (US, 11,641 [66.5%]; Canada, 6958 [62.5%]). When comparing the 2 groups, US positive reactions were more likely to occur in male patients (odds ratio [OR] = 1.40, 95% confidence interval [CI] = 1.31-1.49), older than 40 years (OR = 1.30, 95% CI = 1.22-1.38), Black (OR = 2.67, 95% CI = 2.24-3.19) or Hispanic race (OR = 3.53, 95% CI = 2.61-4.78), and/or patients with scattered generalized dermatitis (OR = 1.96, 95% CI = 1.80-2.13). They were less likely to occur in patients with eczema (OR = 0.61, 95% CI = 0.57-0.65) and Asian race (OR = 0.50, 95% CI = 0.44-0.56). Nickel (US, 16.0%; Canada, 22.4%) and methylisothiazolinone (US, 13.4%; Canada, 11.0%) were the top allergens. The third most frequent was neomycin (US, 11.7%) and fragrance mix I (Canada, 10.2%)., Conclusions: National differences in allergen prevalence and trends exist in North America., Competing Interests: J.S.T. has consulted for Johnson & Johnson, Bayer, Kao Brands, and Equinox Group; received royalties from Decision Support in Medicine; and owns noncontrolling shares of common stock in AstraZeneca, Cigna, Johnson & Johnson, Merck, and Opko Health; a nondependent child is an employee of Pfizer. He is a member of the steering committee of the Cosmetic Ingredient Review. M.J.R. is the American Contact Dermatitis Society Contact Allergy Management Program Director. The other authors have no funding or conflicts of interest to declare., (Copyright © 2021 American Contact Dermatitis Society. All Rights Reserved.)

Competing Interests: The authors have no funding or conflicts of interest to declare.

Competing Interests: A.R.A. received a Pfizer Independent Grant for Learning & Change and has consulted for Henkel. J.S.T. owns noncontrolling common shares of stock in AstraZeneca, Cigna, Merck, Johnson & Johnson, and OPKO Health. He has consulted for Kao Brands and Monsanto (Bayer), is a member of the Cosmetic Ingredient Review Steering Committee, and has a nondependent child employed by Pfizer, Inc. E.M.W. has received an investigator-initiated grant from and served as a consultant for Wen by Chaz Dean. She has also served as a consultant to Noven Pharmaceuticals. D.S. receives royalties from UpToDate (Wolters Kluwer Health). The other authors have no funding or conflicts of interest to declare.

Background: Little is known about the relationship between psoriasis and allergic contact dermatitis (ACD)., Objective: To examine the associations with ACD, related clinical characteristics, and common positive and clinically relevant allergens of patients with a final diagnosis of psoriasis who were referred for patch testing., Methods: Retrospective analysis of 38 723 patients from the North American Contact Dermatitis Group., Results: Patients with a final diagnosis of psoriasis had lower proportions of ACD than those without psoriasis (32.7% vs 57.8%). In multivariable logistic regression models, psoriasis was inversely associated with female sex, Black or Asian race, and history of atopic dermatitis and hay fever. Patients with a final diagnosis of psoriasis were less likely to have one or more positive allergic patch-test reactions or to have a current clinically relevant patch-test reaction to the majority of the most commonly positive and/or relevant allergens. The most clinically relevant allergens included nickel sulfate, methylisothiazolinone, and fragrance mix I., Conclusion: Approximately one-third of patients who were referred for patch testing with a final diagnosis of psoriasis were also diagnosed with ACD. In select patients with suspected psoriasis who also have a clinical presentation suggestive of ACD, patch testing may be helpful., (© 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Vitamin E (tocopherol) a naturally occurring mixture of antioxidants commonly used in topical skin care products, may cause allergic contact dermatitis., Objective: The aim of this study was to characterize positive patch test reactions to tocopherol and tocopherol acetate., Methods: This is a retrospective analysis of North American Contact Dermatitis Group patch test data to tocopherols (dl-α-tocopherol 100% and/or dl-α-tocopherol acetate 100%) from 2001 to 2016., Results: Of the 38,699 patients patch tested to tocopherol and/or tocopherol acetate, 349 (0.9%) had positive reactions; of these, 87.6% were currently relevant. Most (51.4%) were weak (+) and/or not related to occupation (99.1%). Compared with tocopherol-negative patients, tocopherol-positive individuals were more likely to be female (72.5% vs 67.2%, P = 0.0355), have a final primary diagnosis of allergic contact dermatitis (74.2% vs 52.6%, P < 0.0001), and have dermatitis in a scattered generalized distribution (23.8% vs 18.2%, P = 0.0072); they were also less likely to have hand involvement (16.6% vs 22.3%, P = 0.0064). The most common source of tocopherol was personal care products, especially moisturizers., Conclusions: Positive patch test reactions to tocopherols were relatively rare given their widespread use. When positive, current clinical relevance was high. Tocopherol-positive patients were more likely to be female and presented with dermatitis on the face or in a scattered generalized pattern., Competing Interests: A.R.A. received a Pfizer Independent Grant for Learning & Change and has consulted for Henkel. E.M.W. has received research funding from and is a consultant to Wen by Chaz Dean. J.S.T. owns shares of stock in AstraZeneca, Cigna, Merck, Johnson & Johnson, and Opko Health. He has consulted for Kao Brands and Monsanto (Bayer), is a member of the Cosmetic Ingredient Review Steering Committee, and has a nondependent child employed by Pfizer. The other authors have no funding or conflicts of interest to declare., (Copyright © 2021 American Contact Dermatitis Society. All Rights Reserved.)

Background: Sodium disulfite (SD), also known as sodium metabisulfite, is an increasingly recognized cause of allergic contact dermatitis., Objectives: The objective of this work was to characterize individuals with positive patch test reactions to SD as well as analyse reaction strength, clinical relevance, and sources., Methods: This is a retrospective analysis of patients patch tested with SD (1% petrolatum) by the North American Contact Dermatitis Group (NACDG), 2017 to 2018., Results: Of 4885 patients patch tested with SD, 132 (2.7%) had a positive reaction. Common primary anatomic sites of dermatitis were face (28.8%), hands (20.5%), and a scattered/generalized distribution (13.6%). Compared with SD-negative patients, SD-positive patients were more likely male (odds ratio 2.81, 95% confidence interval 1.98-4.00) and/or over 40 years (odds ratio 1.95, 95% confidence interval 1.30-2.94). Reactions were most commonly + (50.4%) or ++ (34.1%); 65.2% were considered currently relevant. About 15.2% were definitively confirmed in sources, commonly personal care products (18.9%, especially hair dye), and drugs/medications/alcoholic beverages (9.1%). Only 2.3% of positive reactions were linked to occupation., Conclusions: Positive reactions to SD occurred in 2.7% of tested patients. Reactions were often clinically relevant and linked to personal care products and drugs/medications/alcoholic beverages., (© 2021 John Wiley & Sons A/S . Published by John Wiley & Sons Ltd.)

Background: Data regarding teledermatology for patch testing are limited., Objectives: Compare patch test readings and final interpretation by two in-person dermatologists (IPDs) with eight teledermatologists (TDs)., Methods: Patch tested patients had photographs taken of 70 screening series of allergens at 48 hours and second readings. Eight TDs reviewed photos and graded reactions (negative, irritant, doubtful, +, ++, +++) at 48 hours and second readings; in addition, they coded a final interpretation (allergic, indeterminant, irritant, negative) for each reaction. TDs rated overall image quality and confidence level for each patient and patch test reaction, respectively. Percentage of TD-IPD agreement based on clinical significance (success, indeterminate, and failure) was calculated. Primary outcome was agreement at the second reading., Results: Data were available for 99, 101, and 66 participants at 48 hours, second reading, and final interpretation, respectively. Pooled failure (+/++/+++ vs negative) at second reading was 13.6% (range 7.9%-20.4%). Pooled failure at 48 hours and final interpretation was 5.4% (range 2.9%-6.8%) and 24.6% (range 10.2%-36.8%), respectively. Confidence in readings was statistically correlated with quality of images and disagreement., Conclusion: For patch testing, teledermatology has significant limitations including clinically significant pooled failure percentages of 13.6% for second readings and 24.6% for final interpretation., (© 2021 John Wiley & Sons A/S . Published by John Wiley & Sons Ltd.)

Background: Little is known about the aetiologies and relevant allergens in paediatric patients with hand eczema (HE)., Objectives: To characterize the aetiologies and determine the proportion of positive and currently relevant allergens in children/adolescents (age < 18 years) with HE referred for patch testing., Methods: A retrospective analysis (2000-2016) of North American Contact Dermatitis Group data was performed., Results: Of 1634 paediatric patients, 237 (14·5%) had involvement of the hands. Final physician diagnoses included allergic contact dermatitis (49·4%), atopic dermatitis (37·1%) and irritant contact dermatitis (16·9%). In multivariable logistic regression models, employment was the only association with increased odds of any HE or primary HE. Children with HE vs. those without HE had similar proportions of positive patch tests (56·1% vs. 61·7%; χ 2 -test, P = 0·11). The five most common currently relevant allergens were nickel, methylisothiazolinone, propylene glycol, decyl glucoside and lanolin. In multivariable logistic regression models of the top 20 relevant allergens, HE was associated with significantly higher odds of currently relevant reactions to lanolin, quaternium-15, Compositae mix, thiuram mix, 2-mercaptobenzathiazole and colophony. The allergens with the highest mean significance-prevalence index number were methylisothiazolinone, carba mix, thiuram mix, nickel and methylchloroisothiazolinone/methylisothiazolinone., Conclusions: Children with HE who were referred for patch testing had a high proportion of positive patch tests, which was similar to the proportion found in children without HE. Children with HE had a distinct and fairly narrow profile of currently relevant allergens., (© 2021 British Association of Dermatologists.)

Background: Few studies have examined the relationship between nummular (discoid) eczema (NE) and allergic contact dermatitis (ACD)., Objective: To examine trends, associations, and clinical relevance of ACD in patients with NE who were referred for patch testing., Methods: Retrospective analysis of 38 723 patients from the North American Contact Dermatitis Group., Results: Overall, 748 patients (1.9%) were diagnosed with NE; 23.9% had a concomitant diagnosis of ACD. The prevalence of NE fluctuated over time between 2001 and 2016, with no overall change in prevalence in diagnosed NE. In multivariable logistic regression models, NE increased steadily with age and was associated with male sex and Asian and other race/ethnicity, and inversely associated with a history of atopic dermatitis (AD) and hay fever. Patients with NE had lower proportions of one or more positive allergic reactions and lower odds of a positive reaction in multiple individual allergens. The most commonly relevant allergens in patients with NE were formaldehyde 2.0% aq., methylisothiazolinone, quaternium 15, fragrance mix I, and propylene glycol., Conclusion: NE is a heterogeneous disorder with distinct subsets of lesional distributions and a profile of relevant allergens, especially formaldehyde and formaldehyde releasers. Nearly one in four patients with NE had ACD, supporting the role of patch testing in patients with NE., (© 2021 John Wiley & Sons A/S . Published by John Wiley & Sons Ltd.)

Background: Methyldibromoglutaronitrile/phenoxyethanol (MDBGN/PE) is a broad-spectrum preservative mixture used in consumer and industrial products., Objectives: The aims of the study were (1) to characterize the prevalence and clinical relevance of patch test reactions to MDBGN/PE and the epidemiology of positive patients and (2) to determine the frequency of concomitant reactions of MDBGN/PE and its components., Methods: This study used a retrospective analysis of cross-sectional data compiled by the North American Contact Dermatitis Group from 1994 to 2018., Results: Of 55,477 tested patients, 2674 (4.8%) had positive patch test reactions to MDBGN/PE (1.0%-2.5% petrolatum [pet]); most were + (63.3%) or ++ (22.3%). Clinical relevance was considered definite in 3.0% and probable in 19.3% of reactions. Common dermatitis sites included the hands (26.4%), scattered/generalized distribution (24.7%), and the face (18.3%). Patients with a positive reaction to MDBGN/PE and/or MDBGN and/or PE were significantly more likely to be male and older than 40 years and/or had hand dermatitis (P ≤ 0.0033). Positivity to MDBGN/PE 2.0% pet decreased significantly over time (from 6.0% in 1998-2000 to 2.5% in 2017-2018, P < 0.0001). Personal care products were the most common exposure source (53.2%)., Conclusions: Over time, positivity to MDBGN/PE 2.0% pet decreased significantly from 6.0% (in 1998-2000) to 2.5% (in 2017-2018). The high proportion of weak (63.3%) reactions underscore the need for careful interpretation of patch test sites. Important demographic associations included male sex and age older than 40 years., Competing Interests: A.R.A. received a grant from Pfizer Independent Grant for Learning & Change and has consulted for Henkel. J.S.T. owns noncontrolling shares of stock in AstraZeneca, Cigna, Merck, Johnson & Johnson, and Opko Health. He has consulted for Kao Brands and Monsanto (Bayer), is a member of the Cosmetic Ingredient Review Steering Committee, and has a nondependent child employed by Pfizer. E.M.W. has received an investigator-initiated grant from and served as a consultant for Wen by Chaz Dean. She has also served as a consultant for Noven Pharmaceuticals. D.S. receives royalties from UpToDate (Wolters Kluwer Health). The other authors have no funding or conflicts of interest to declare., (Copyright © 2021 American Contact Dermatitis Society. All Rights Reserved.)

Objectives: Mercapto compounds are a category of rubber accelerators that may cause allergic contact dermatitis. This study characterizes patch test reactions to mercaptobenzothiazole (MBT) and mercapto mix (MM) in a large North American population., Methods: The 1994-2016 North American Contact Dermatitis Group screening series data were analyzed. Patients with allergic reactions to either MBT or MM (mercapto+) were included. The following characteristics were analyzed: strength of reaction, clinical and occupational relevance, coreactivity with other rubber accelerators, and sources of exposure., Results: A total of 49,795 patients were tested to mercapto compounds from 1994 to 2016; 633 (1.3%) had positive reactions to MBT and/or MM. The frequency to both MBT and MM significantly decreased over time (P < 0.0001). Mercapto+ patients were significantly more likely to be male, have occupationally related skin disease, and report involvement of the hands and/or feet (P < 0.0001). They were significantly less likely to have face, scalp/ears/neck, or trunk involvement (P ≤ 0.0001). There was significant coreactivity with carba mix (23.4%) and thiuram mix (32.5%). Mercaptobenzothiazole and MM reactions were frequently clinically (81.7% and 83.5%, respectively) and occupationally relevant (29.8% and 33.4%, respectively). Gloves were the most common source (31.3% and 30.9%, respectively)., Conclusions: Patch test positivity to mercapto compounds significantly decreased from 1994 to 2016 but remains clinically and occupationally relevant., Competing Interests: J.S.T. owns noncontrolling common stock shares in AstraZeneca, Cigna, Merck, Johnson & Johnson, and Opko Health. He has consulted for Kao Brands and Monsanto (Bayer) and is a member of the Cosmetic Ingredient Review Steering Committee, and a nondependent child is employed by Pfizer. The other authors have no funding or conflicts of interest to declare., (Copyright © 2020 American Contact Dermatitis Society. All Rights Reserved.)

Background: The association between atopic dermatitis (AD) and allergic contact dermatitis (ACD) is controversial., Objective: To analyze the prevalence, reaction strength, and trends of the most commonly positive and relevant allergens in patients with AD referred for patch testing., Methods: This was a retrospective analysis of 38,482 patients from the North American Contact Dermatitis Group, 2001 to 2016., Results: Most adults (56.0%) and children (52.8%) with a history of AD had a final diagnosis of ACD. Adults (66.5% vs 65.6%; χ 2 , P = .1459) and children (61.4% vs 62.3%, P = .7074) with or without a history of AD had similar proportions of one or more allergic patch test reactions. Adults with a history of AD had a greater number of allergic patch test positive reactions than those without it (2.0 ± 2.4 vs 1.9 ± 2.3; t test, P < .0001), whereas children did not (1.5 ± 1.8 vs 1.4 ± 1.6; P = .3839). Nickel sulfate, methylisothiazolinone, formaldehyde, fragrance mix I, sodium gold thiosulfate, and thimerosal were the most common allergens in adults and children with a history of AD. In multivariable logistic regression models, adults with versus without a history of AD had increased odds of reacting to 10 of the top 25 North American Contact Dermatitis Group screening allergens. Most allergens had similar strengths of reaction in adults or children with and without a history of AD or a current AD diagnosis; cobalt, fragrance mix I, and propylene glycol had weaker reactions. In multivariable logistic regression, adults with versus without an AD history had increased odds of relevance for 10 of the 25 most currently relevant allergens, whereas children with an AD history did not have increased relevance for any specific allergens., Conclusions: Most patients referred for patch testing with AD history had a final diagnosis of ACD. Patients with AD history had a similar likelihood of having a positive patch test reaction as those without an AD history. Adults with an AD history had a higher number of positive patch test reactions., (Copyright © 2021 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

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., Competing Interests: Disclosure The authors have nothing to disclose., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background/objective: This study characterizes concomitant reactions to carba mix (CM) and thiuram mix (TM) in a large North American population. Because thiurams and dithiocarbamates have structural similarity, concomitant reactions are expected., Methods: The 1994-2016 North American Contact Dermatitis Group data were analyzed. Patients with a final reaction interpreted as "allergic" to either CM or TM were included., Results: A total of 49,758 patients were tested to both CM and TM. A total of 3437 (6.9%) had positive reactions to CM and/or TM including the following groups: CM+ only (n = 1403, 40.8%), TM+ only (n = 1068, 31.0%), or both (n = 966, 28.1%). A total of 47.5% of TM+ patients were positive to CM and 40.8% of CM+ patients were positive to TM. Male sex, occupationally related dermatitis, and hand involvement were significantly more common in individuals positive to CM and/or TM as compared with those who were negative (P < 0.0001). More than 80% of CM+/TM+ reactions were currently relevant. Gloves were the most common source of CM and TM; clothing and footwear were also frequent., Conclusions: Carba mix and TM remain important, clinically relevant allergens. Although significant concomitant reaction frequency was demonstrated, more than half of the patients reacting to either CM or TM would have been missed if both had not been tested, underscoring the importance of testing to both., Competing Interests: J.S.T. owns noncontrolling common stock shares in AstraZeneca, Cigna, Merck, Johnson & Johnson, and Opko Health. He has consulted for Kao Brands and Monsanto (Bayer), is a member of the Cosmetic Ingredient Review Steering Committee, and has a nondependent child who is employed by Pfizer. The other authors have no conflicts of interest to declare., (Copyright © 2020 American Contact Dermatitis Society. All Rights Reserved.)

Background: Eyelid dermatitis is a common dermatologic complaint., Objective: To characterize patients with eyelid dermatitis., Methods: Retrospective analysis (1994-2016) of North American Contact Dermatitis Group data., Results: Of 50,795 patients, 2332 (4.6%) had eyelid dermatitis only, whereas 1623 (3.2%) also had dermatitis of the eyelids and head or neck. Compared with patients without eyelid involvement (n = 26,130), groups with eyelid dermatitis only and dermatitis of the eyelid and head or neck were significantly more likely to be female, white, and older than 40 years, and to have a history of hay fever, atopic dermatitis, or both (P < .01). Final primary diagnoses included allergic contact dermatitis (eyelid dermatitis only: 43.4%; dermatitis of the eyelid and head or neck: 53.5%), irritant contact dermatitis (eyelid dermatitis only: 17.0%; dermatitis of the eyelid and head or neck: 9.8%), and atopic dermatitis (eyelid dermatitis only: 13.1%; dermatitis of the eyelid and head or neck: 13.8%). Top 5 currently relevant allergens included nickel sulfate (eyelid dermatitis only: 18.6%; dermatitis of the eyelid and head or neck: 22.5%), fragrance mix I (eyelid dermatitis only: 16.5%; dermatitis of the eyelid and head or neck: 18.3%), methylisothiazolinone (eyelid dermatitis only: 16.5%; dermatitis of the eyelid and head or neck: 17.7%), gold sodium thiosulfate (eyelid dermatitis only: 14.7%; dermatitis of the eyelid and head or neck: 11.4%), and balsam of Peru (eyelid dermatitis only: 11.9%; dermatitis of the eyelid and head or neck: 12.6%). Both eyelid-involvement groups were significantly more likely to react to gold sodium thiosulfate, carmine, shellac, dimethylaminopropylamine, oleamidopropyl dimethylamine, and thimerosal (P < .05) compared with the no eyelid involvement group., Limitations: Lack of specific distribution patterns of eyelid dermatitis and no long-term follow-up data., Conclusion: Patch testing remains a critical tool in evaluating patients with eyelid dermatitis., (Published by Elsevier Inc.)

Background: Scalp conditions are often multifactorial., Objective: To characterize patients with scalp involvement and patch-testing outcomes., Methods: Retrospective cross-sectional analysis of North American Contact Dermatitis Group data (1996-2016). Study groups included patients with scalp involvement (≤3 anatomic sites coded) with or without additional sites., Results: A total of 4.8% of patients (2331/48,753) had scalp identified as 1 of up to 3 affected anatomic sites. Approximately one-third of "scalp-only" individuals had a specific primary diagnosis of allergic contact dermatitis (38.6%), followed by seborrheic dermatitis (17.2%) and irritant contact dermatitis (9.3%). When adjacent anatomic sites were affected, allergic contact dermatitis was more frequently identified as the primary diagnosis (>50%). The top 5 currently clinically relevant allergens in scalp-only patients were p-phenylenediamine, fragrance mix I, nickel sulfate, balsam of Peru, and cinnamic aldehyde. Methylisothiazolinone sensitivity was notable when adjacent anatomic sites were involved. The top 3 specifically identified sources for scalp-only allergens were hair dyes, shampoo/conditioners, and consumer items (eg, hair appliances, glasses)., Limitations: Tertiary referral population., Conclusion: Isolated scalp involvement was less likely to be associated with allergic contact dermatitis than when adjacent anatomic sites were involved. Overlap with multiple diagnoses was frequent, including seborrheic dermatitis, irritant dermatitis, other dermatoses, or all 3. p-Phenylenediamine was the most common allergen., (Published by Elsevier Inc.)

Background: Hand eczema (HE) is a heterogeneous and burdensome disorder., Objective: To characterize the clinical characteristics, etiologies and allergen relevance in adults with HE referred for patch testing., Methods: Retrospective analysis (2000-2016) of North American Contact Dermatitis Group data (n = 37,113)., Results: Overall, 10,034 patients had HE, with differences of overlap between allergic contact, irritant contact, and atopic dermatitis. Allergic contact HE fluctuated, whereas atopic HE steadily increased, and irritant HE decreased over time. HE was associated with higher proportions of positive patch tests (67.5% vs 63.8%; χ 2 , P < .0001). The five most common clinically relevant allergens were methylisothiazolinone, nickel, formaldehyde, quaternium-15, and fragrance mix I. HE was associated with significantly higher odds of positive patch test reactions and clinical relevance in 13 and 16 of the 25 most common allergens, respectively, including preservatives, metals, topical medications, and rubber accelerators., Limitations: No data on HE phenotype., Conclusion: HE in adults was associated with higher proportions of positive patch tests, with a heterogeneous profile of allergens. Patch testing remains an important tool in the evaluation of patients with HE., Competing Interests: Conflicts of interest None disclosed., (Copyright © 2020 American Academy of Dermatology, Inc. All rights reserved.)

Background: Preservatives are often necessary components of commercial products. Large-scale North American studies on preservative allergy are limited., Objective: To evaluate demographics, positive patch test reactions (PPTRs), clinical relevance, and trends for preservatives tested by the North American Contact Dermatitis Group., Methods: We conducted a retrospective cross-sectional analysis of North American Contact Dermatitis Group patch testing results of preservatives from 1994 through 2016., Results: A total of 50,799 patients were tested; 11,338 (22.3%) had a PPTR to at least 1 preservative. The most frequent reactions were to methylisothiazolinone 0.2% aqueous (aq) (12.2%), formaldehyde 2% aq (7.8%), formaldehyde 1% aq (7.8%), quaternium-15 2% petrolatum (pet) (7.7%), and methyldibromo glutaronitrile/phenoxyethanol 2% pet (5.1%). Paraben mix 12% pet (1%), iodopropynyl butylcarbamate 0.1% pet (0.4%), benzyl alcohol 1% pet (0.3%), and phenoxyethanol 1% pet (0.2%) had the lowest PPTRs. Linear regression analysis of preservatives tested showed that only methylchloroisothiazolinone/methylisothiazolinone 0.01% aq (parameter estimate, 0.42; 95% CI, 0.17-0.66; P < .005) had a significant increase in PPTRs over time., Limitations: Collected variables are dependent on clinical judgment. Results may be prone to referral selection bias., Conclusions: This large North American study provides insight on preservative PPTRs and trends from 1994 through 2016., (Copyright © 2020 American Academy of Dermatology, Inc. All rights reserved.)

Background: Carmine is a natural red dye that may cause allergic contact dermatitis., Objective: The aim of this study was to analyze patch test reactions to carmine (2.5% in petrolatum) and characterize carmine-positive patients., Methods: This study conducted a retrospective analysis of North American Contact Dermatitis Group data compiled between 2011 and 2012., Results: Of 4240 patients patch tested to carmine, 132 (3.1%) had reactions with a final interpretation of "allergic" (positive). Carmine-positive patients were significantly more likely to be female (77.7% vs 68.3%; P = 0.0237) and have a final primary diagnosis of allergic contact dermatitis (74.8% vs 47.2%; P < 0.0001). As compared with carmine-negative patients, carmine-positive patients were significantly more likely to have involvement of all facial sites combined (48.1% vs 29.9%; P < 0.0001) and the lips (7.6% vs 3.6%; P = 0.0166). At final reading, most carmine reactions were weak (+; 64.9%). Approximately half (53.4%) were currently clinically relevant; identified sources were primarily personal care products (77.1%), especially makeup (31.4%) and lip products (8.6%)., Conclusions: Weak patch test reactions to carmine should be interpreted with caution. Allergic contact dermatitis to carmine should be suspected in women with facial and/or lip dermatitis, especially those using carmine-containing cosmetics., (Copyright © 2021 American Contact Dermatitis Society. All Rights Reserved.)