Allergic Patch Test Research Articles

Severely compromised supply of patch test allergens in Europe hampers adequate diagnosis of occupational and non-occupational contact allergy. A European Society of Contact Dermatitis (ESCD), European Academy of Allergy and Clinical Immunology (EAACI), European Academy of Dermatology and Venereology (EADV) task forces 'Contact Dermatitis' and 'Occupational Skin Disease' position paper.

Patch testing is the only clinically applicable diagnostic method for Type IV allergy. The availability of Type IV patch test (PT) allergens in Europe, however, is currently scarce. This severely compromises adequate diagnostics of contact allergy, leading to serious consequences for the affected patients. Against this background, the European Society of Contact Dermatitis (ESCD) has created a task force (TF) (i) to explore the current availability of PT substances in different member states, (ii) to highlight some of the unique characteristics of Type IV vs. other allergens and (iii) to suggest ways forward to promote and ensure availability of high-quality patch testing substances for the diagnosis of Type IV allergies throughout Europe. The suggestions of the TF on how to improve the availability of PT allergens are supported by the ESCD, the European Academy of Allergy and Clinical Immunology, and the European Academy of Dermatology and Venereology and intend to provide potential means to resolve the present medical crisis.

Diagnostic gap due to missing patch test allergens—status quo and possible scenarios for mitigation

SummaryAccording to European Directive 2001/83/EC, test and therapeutic allergens are medicinal products in all Member States of the European Union. This applies equally to prick test and to patch test (PT) allergens (haptens). All test allergens commercially marketed in Germany are finished medicinal products requiring marketing authorization (MA). Currently, 211 PT substances are authorized in Germany, and an additional 59 are in an ongoing MA process and are marketable under a transitional provision until a decision on MA is made. The regulatory guidance (CMDh/399/2019) of the Co-ordination Group for Mutual Recognition and Decentralized Procedures—Human (CMDh), published in July 2020, specifies the regulatory requirements for different allergen products. Due to differences in origin and exposure, use, mode of action, and safety risks, the guideline clearly differentiates between products with active ingredients of biological origin (allergen extracts from natural source materials) and products with active ingredients of non-biological origin (hapten-based PT substances). Currently, guideline-compliant patch testing is hampered by the lack of numerous commercial PT allergens from the standard and special test series. Background and possible scenarios for mitigation are presented here.

Impact of dupilumab on patch test results and allergic contact dermatitis: A prospective multicenter study

Limited and conflicting data have been reported on the impact of dupilumab (DUPI) on patch test (PT) results and its efficacy against allergic contact dermatitis (ACD). This study was undertaken to analyze PT reactivities and relevance during treatment with DUPI to determine whether they could detect ACD in patients with uncontrolled or worsened atopic dermatitis (AD) who were receiving this agent. This prospective, multicenter study examined 76 DUPI-treated patients who had undergone PTs. The relevant information was collected during 3 visits. Overall, 36 patients (47%) had ≥1 positive PT reaction, and 142 PT results were positive. Twenty-three patients (30%) had ≥1 positive and clinically relevant PT result. Five of them had clinical eczema improvement after allergen avoidance. We compared the PT results of 36 patients before and during DUPI therapy, representing 1230 paired PT allergens, of which 1022 were the same, 34 were positive, 44 were lost, and 130 were uninterpretable. Because the number of patients included remains limited, our findings should be confirmed with a larger sample. Our results confirmed the usefulness of PTs for patients receiving DUPI, with good PT reproducibility. We suggest that all DUPI-treated patients with AD developing partial responses or experiencing symptom worsening should undergo PTs to look for contact sensitization.

Patch Testing With Cobalt in Adults: A North American Contact Dermatitis Group Experience, 2001-2018.

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.

Allergic Patch Testing in Dermatology

Allergic Patch Testing in Dermatology

Screening for Allergic Contact Dermatitis Based on Pattern of Patch Test Results: A Retrospective Study

Abstract Background: Contact allergies are associated with morbidity worldwide. Purpose: To investigate the patterns of sensitization to contact allergens in a local population. Methods: A retrospective study investigated patch test reactivity among patients with a clinical diagnosis of contact dermatitis referred to the dermatology clinic at King Fahad Armed Forces Hospital, Jeddah, between January 2021 and January 2023. Pregnant women, immunosuppressed patients, and those receiving immunosuppressive therapy were excluded. Only 92 of 101 referred patients underwent patch testing after fulfilling requirements. The patch test was performed using a Thin-layer Rapid-Use Epicutaneous patch test containing 35 contact allergenic elements and one control (total = 36). Results: Among 92 patients, 35 (38%) were males, and 57 (62%) were females. Of these, 62 (67.4%) patients had a positive patch test and reacted to one or more allergens. The most common sensitizing allergens were p-phenylenediamine (PPD), gold sodium thiosulfate, and disperse blue 106, with equal positive reactions in 16 (25.8%) patients, followed by nickel sulfate in 13 (21%), p-tert-butylphenol formaldehyde resin in eight (13%), fragrance mix in 7 (10.8%), and epoxy resin in six (9.2%) patients. No significant sex differences were found among patients with contact dermatitis where notable patch test allergen reactivity was observed. Conclusion: Patch test reactivity to PPD, gold sodium thiosulfate, and disperse blue 106 was high. The pattern of contact allergy observed here highlights the need for large-scale investigations to identify local allergens for contact allergy and formulate policies for avoiding exposure.

Analysis of Positive Patch Test Allergens in Allergic Contact Dermatitis Patients with Atopic Dermatitis.

There has been debate regarding whether patients with atopic dermatitis (AD) have an altered frequency of contact allergen sensitization. Increased exposure to topical medications and moisturizers as well as impaired skin barrier function increase the risk of contact sensitization, whereas the Th2-skewed inflammatory pathway of AD is associated with a reduced risk. This retrospective study was performed to determine the characteristics of contact sensitization in allergic contact dermatitis (ACD) patients with a current or past history of AD. A clinical record review was conducted for patients referred to Ewha Womans University Medical Center, for patch tests between March 2017 and March 2021. We compared the rates of contact sensitization between ACD patients with and without AD. In total, 515 patch test results were reviewed and divided into the AD group (n=53) and non-AD group (n=462). The AD group showed decreased any-allergen positivity (1+, 2+, or 3+) (56.6%) compared to the non-AD group (72.9%) (p=0.013). The positivity rate for budesonide was significantly higher in the AD group (p=0.011), while the prevalence of a positive result for balsam of Peru was higher in the non-AD group (p=0.036). Nickel sulfate, cobalt chloride, and potassium dichromate were the most common sensitized allergens in both groups. Our study shows a decreased prevalence of contact sensitization in AD patients compared to non-AD patients. Clinicians should be aware of the risk of corticosteroid allergies in ACD patients with history of AD.

Various techniques for marking patch test sites.

Patch test helps in identifying the allergen causing allergic contact dermatitis. Proper identification of the site of individual patch test allergen is very important for identifying the positive allergen. In this article, various techniques for markings patch test sites are discussed.

Chronic actinic dermatitis: A 5-year clinical analysis of 488 patients in China.

Chronic actinic dermatitis (CAD) is a spectrum of diseases with chronic photosensitivity occurring mostly among middle-aged and older men. We seek to explore the characteristics and pathogenesis of CAD among the Chinese population. The medical records of 488 CAD cases diagnosed by phototesting at Huashan Hospital, Fudan University from January 2014 to December 2018 were analyzed retrospectively. Among the 488 patients, 344 were male and 144 were female. 84.8% of the cases were over 40 years old at the age of onset, while the remaining with an early age of onset had a prevalence of atopic history of 21.6%. Up to 45.0% of the patients reported excessive sun exposure and outdoor activities before the initiation of symptoms. The typical skin lesions were erythema, papules and plaques laid predominantly in sun-exposed areas. 42.8% of the cases showed sensitivity to UVB only, 20.7% were both sensitive to UVA and UVB, and 18.2% had UVA sensitivity only. The most predominant photoallergens were chlorpromazine (80.1%), thimerosal (17.2%), potassium dichromate (12.7%), etc. The most prevalent patch test allergens were potassium dichromate (24.4%), thimerosal (20.5%), formaldehyde (16.8%), etc. CONCLUSIONS: CAD was more commonly seen in males over 40 years old. The action spectrum of Chinese patients is primarily in the UVB range. Exposure to excessive sunlight or contact allergens and photoallergens are important risk factors. Photobiology tests are essential in detecting photosensitivity and recognizing potential photosensitizers. Early avoidance of confirmed photoallergens and sun exposure may prevent photosensitive reactions from progressing into persistent photosensitivity.

Patch testing with cobalt in children and adolescents: North American contact dermatitis group experience, 2001–2018

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. 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. A retrospective analysis of children (<18 years) patch tested to cobalt by the North American Contact Dermatitis Group between 2001 and 2018. 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. 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.

Sorbitan sesquioleate: a rare contact allergen that is also an important indicator of allergic contact dermatitis from crossreacting compounds as well as for false-positive fragrance allergy.

Controversy exists about the addition of sorbitan sesquioleate (SSO) to the European baseline series for concomitant patch testing, particularly with fragrance mix (FM) I and Myroxylone pereirae (MP), which both contain SSO as an emulsifier. To investigate SSO contact sensitization and concomitant positive patch test reactions to FM I or MP in Turkey. This was a retrospective analysis of 840 patients consecutively patch tested with SSO 20% petrolatum between 1996 and 2020. The prevalence of SSO sensitization was 0.6% (5 of 840). In four of the five patients, clinical relevance could be established from SSO crossreactants, mainly in moisturizers and topical pharmaceuticals other than corticosteroids. Positive patch test reactions with unknown clinical relevance were observed to FM I or MP (both containing 5% SSO) in 71.4% of patients with a positive/questionable positive reaction to SSO (P < 0.001) and to other patch test allergens containing 1-5% SSO. SSO was a very good indicator for positive patch test reaction with unknown clinical relevance to fragrances and other allergens containing 1-5% SSO. We suggest that SSO should be tested as a negative control with any commercially available patch test allergen containing SSO at any concentration. Moreover, clinicians should be alert for SSO synonyms and for other sorbitan derivatives in product labels, as SSO itself might not be the culprit but an indicator for crossreacting allergens.

Novel insights into contact dermatitis

Contact dermatitis is a common disease that is caused by repeated skin contact with contact allergens or irritants, resulting in allergic contact dermatitis (ACD) and/or irritant contact dermatitis. Attempts have been made to identify biomarkers to distinguish irritant and allergic patch test reactions, which could aid diagnosis. Some promising candidates have recently been identified, but verification and validation in clinical cases still need to be done. New causes of ACD are constantly being recognized. In this review, 10 new contact allergens from recent years, several relating to anti-aging products, have been identified. Frequent allergens causing considerable morbidity in the population, such as the preservative methylisothiazolinone, have been regulated in the European Union. Asignificant drop in the number of cases has been seen, whereas high rates are still occurring in other areas such as North America. Other frequent causes are fragrance allergens, especially the widely used terpenes and acrylates found in medical devices for control of diabetes. These represent unsolved problems. Recent advances in immunology have opened the way for a better understanding of the complexity of contact dermatitis, especially ACD-a disease that may be more heterogenous that previous understood, with several subtypes. With the rapidly evolving molecular understanding of ACD, the potential for development of new drugs for personalized treatment of contact dermatitis is considerable.

Occupational Contact Dermatitis in Dental Personnel: A Retrospective Analysis of the North American Contact Dermatitis Group Data, 2001 to 2018.

Dental personnel are at risk of developing occupational contact dermatitis. 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. The study used a retrospective, cross-sectional analysis of the North American Contact Dermatitis Group (NACDG) data, 2001-2018. 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%). Occupational contact dermatitis is common in dental personnel referred for patch testing. Comprehensive testing beyond screening series is important in these patients.

Chronic hand eczema: clinical characterization, aetiology, concomitant foot eczema and polysensitization.

Chronic hand eczema (CHE) is a disabling dermatosis that presents with concomitant conditions, such as foot eczema and contact sensitization To identify the characteristics of the CHE population, with particular emphasis on occupational relevance and evaluation of concomitant foot eczema and polysensitization A total of 2,926 patch-tested patients, presenting with CHE from different specialized dermatological units from 2004 to 2014, were evaluated. A global descriptive characterization was performed including hand subtype analysis, as well as accurate evaluation of polysensitization The most frequent global CHE diagnostic was irritant contact dermatitis (42%) and, for patients with foot and chronic hand eczema (FCHE), allergic contact dermatitis (28%). Of CHE cases, 39% showed occupational relevance. Positivity to at least one allergen was found in 55% of patients, with nickel and methylisothiazolinone (MI) being the most prevalent. Methylchloroisothiazolinone/MI, nickel and potassium dichromate showed the highest occupational relevance. Patients with concomitant FCHE (8%) showed greater sensitization for potassium dichromate and cobalt chloride. Twelve percent were polysensitized, with MI being the most frequently involved contact allergen Patch testing for FCHE and CHE revealed a specific contact allergen and occupational profile. MI was the most frequently reported allergen related to polysensitization in CHE.

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

Patch test (PT) readings are recommended after 48h and 72h (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. 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. 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 50years and with a negative irritant control containing sodium lauryl sulphate. Of note, application of the PT allergens for 48h instead of 24h was positively associated with late PT reactions. 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.

Results of patch tests (using Indian standard battery of allergens) in cement workers with clinically diagnosed allergic contact dermatitis to cement: A cross-sectional study

Objectives: The objective of the study was to identify the allergens showing positive patch test reaction (using Indian standard battery of allergens) in cement workers with clinically diagnosed allergic contact dermatitis (CD) to cement attending a tertiary referral center. Materials and Methods: We included cement workers with clinically diagnosed allergic CD to cement who attended the dermatology outpatient clinic of our tertiary referral center from January 2013 to December 2013. We did patch testing in all the cases ( after subsidence of active dermatitis) with Indian standard battery of patch test allergens and documented the allergens that showed a positive reaction. Results: Forty-seven (94%) of the 50 study participants showed a positive reaction to one or more of the allergens. The most common allergen that showed a positive reaction was potassium dichromate (43/50, 86%). Twenty-five patients (50%) showed positive reactions to more than 1 allergen. Four patients (8%) showed positive reactions only to allergens that were not seen in cement. Limitations: Small sample size and lack of information on clinical response of dermatitis to avoidance of identified allergen were the major limitations. Conclusion: Twenty-five (50%) patients showing positive reactions to more than 1 allergen tested and 4 (8%) showing positive patch test reaction to none of the allergens in cement (but to other allergens) highlight the role of patch testing in identifying the probable allergens in patients with clinically diagnosed allergic CD to cement.

Patch Test Reactions Associated With Topical Medications: A Retrospective Analysis of the North American Contact Dermatitis Group Data (2001-2018).

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). 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. 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. 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.

A baseline patch test series for New Zealand.

Patch testing is the gold standard diagnostic test for allergic contact dermatitis and needs to be relevant to the region and the population being tested. The aim of this study was to develop a specific New Zealand baseline series (NZBS). We performed a retrospective case note review of patients attending four regional patch test centres between 2008 and 2020. Demographic and diagnostic information was collected for each patient along with results of patch testing. Using the results of this review, a group of 11 dermatologists with an interest in contact dermatitis agreed on a core group of allergens for inclusion in an NZBS, based on the frequency of positive reactions and allergens of interest. The remaining potential allergens were ranked by each dermatologist using an online questionnaire, with inclusion in the final NZBS by consensus. Results from 2402 patients (67% female, mean age 44 years) from Auckland, Wellington, Palmerston North and Christchurch were collated. The 10 most frequent positive (relevant and non-relevant) allergens were nickel sulfate (22.0%), fragrance mix I (8.6%), cobalt chloride (7.3%), Myroxylon pereirae (5.6%), colophonium (5.1%), p-phenylenediamine (4.9%), methylisothiazolinone/methylchloroisothiazolinone (4.1%), fragrance mix II (3.9%), potassium dichromate (3.5%) and methylisothiazolinone (3.4%). Based on these results, a core series of 30 allergens was developed, with an additional 30 allergens added to form the extended series (total 60 allergens). The baseline series of patch test allergens for routine use in New Zealand (NZBS) is based on national patch test data and expert consensus.

Patch testing with expired Indian patch test kits: Results of a pilot study

The reliability of patch testing with expired Indian standard patch test kits has been not evaluated before. Thirty adults (men:women 25:5) with allergic contact dermatitis were divided into three groups of ten patients each for patch testing by Finn chamber® method using Indian standard patch test kits having expiry in 2016, 2015 and 2014. The results were compared with those from a new kit with 2018 expiry. Ten patients in group-1, eight patients in group-2 and seven patients in group-3 developed positive reactions of identical intensities and mostly from identical allergens from all four kits. The major contact allergens eliciting positive reactions of identical intensities were parthenium in nine, five and three patients, colophony in four, one and zero patients, fragrance mix in three, three and one patients, thiuram mix in three, one and one patients, and paraphenylene diamine in two, one and three patients from group-1,-2, and -3, respectively. Small number of patients in each group remains the major limitation of the study. Whether or not these results can be extrapolated with patch test results from other similar patch test kits available across countries also needs confirmation. The patch test allergens can be used beyond labeled expiry dates but needs confirmation by a few large studies and using other available patch test kits. This is important as the relevance of patch test results for individual allergen in this scenario may remain debatable requiring careful interpretation.

Prevalence and Trend of Allergen Sensitization in Adults and Children with Atopic Dermatitis Referred for Patch Testing, North American Contact Dermatitis Group Data, 2001-2016

The association between atopic dermatitis (AD) and allergic contact dermatitis (ACD) is controversial. To analyze the prevalence, reaction strength, and trends of the most commonly positive and relevant allergens in patients with AD referred for patch testing. This was a retrospective analysis of 38,482 patients from the North American Contact Dermatitis Group, 2001 to2016. 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%; χ2, 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. 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.