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Background: Contact allergy is common in children, but may be underdiagnosed. Importantly, the clinical relevance of specific allergies is subject to constant change, and it is therefore important to continuously monitor the trends and changes of contact allergies in the paediatric population., Objectives: To identify possible changes in contact allergy and allergic contact dermatitis among Danish children referred for patch testing., Methods: A retrospective study was performed based on patch test data from the Danish National Database of Contact allergy. The current data were compared with previously published data on Danish children referred for patch testing., Results: Between 2012 and 2016, 1573 children and adolescents were patch tested. Overall, 385 (24.5%) had at least 1 positive patch test reaction. The overall prevalence was similar in boys and girls, across age groups, and in patients with and without atopic dermatitis. Statistically significant increases in contact allergy to fragrances and isothiazoliones were seen, whereas a decrease in nickel allergy was found., Conclusion: Allergic contact dermatitis continues to be a common disease in children, and is even significantly increasing for some allergens., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Occupational contact dermatitis among hairdressers is frequent, owing to daily exposure to irritants and allergens., Objectives: To identify sensitization to the most common allergens associated with the occupation of hairdressing., Methods: Patch test results of 399 hairdressers and 1995 matched controls with contact dermatitis, registered by the Danish Contact Dermatitis Group between January 2002 and December 2011, were analysed. All patients were patch tested with the European baseline series, and hairdressers were additionally tested with the hairdressing series., Results: Occupational contact dermatitis (p < 0.001) and hand eczema (p < 0.001) were observed significantly more often among hairdressers than among controls. Atopic dermatitis was less commonly observed among hairdressers (21.3%) than among controls (29.4%) (p < 0.01). Allergens from the European baseline series with a statistically significant association with the occupation of hairdressing were p-phenylenediamine, thiuram mix, and benzocaine. Frequent sensitizers from the hairdressing series were ammonium persulfate, toluene-2,5-diamine, 3-aminophenol, and 4-aminophenol. Cysteamine hydrochloride and chloroacetamide emerged as new sensitizers., Conclusions: These results indicate a healthy worker effect among hairdressers diagnosed with eczema. Ammonium persulfate and p-phenylenediamine remain frequent sensitizers in hairdressers with contact dermatitis. Cysteamine hydrochloride and chloroacetamide should be included in future surveillance studies., (© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: We have previously reported patch test reactivity to nickel sulphate in a cohort of unselected infants tested repeatedly at 3-18 months of age. A reproducible positive reaction at 12 and 18 months was selected as a sign of nickel sensitivity provided a patch test with an empty Finn chamber was negative. A reproducible positive reaction was seen in 8.6% of the infants. The objective of this study is to follow-up on infants with alleged nickel sensitivity., Methods: A total of 562 infants were included in the cohort and patch tested with nickel sulphate (ICDRG guidelines). The 26 children with a positive patch test reaction to nickel sulphate at 12 and 18 months were offered repeated patch tests at 3 and 6 yr., Results: Among the 21 children tested at both 12 months, 18 months and at 3 and 6 yr only 2 of 21 had reproducible nickel reactions (one clinically relevant), 13 of 21 were negative and 6 of 21 were negative at 3 or 6 yr., Conclusions: Only 9.5% of the children had reproducible nickel sulphate reactivity, while 62% became negative. The results are noteworthy and can be interpreted in different ways: Repeated nickel patch tests did not cause patch test sensitization. The test reactions in infancy are probably of irritant or non-specific nature. Hence, nickel patch tests should only be performed in small children if there is a clinical suspicion of nickel-induced allergic contact dermatitis., (© 2012 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.)

Background: Previous studies have suggested that the atopy patch test (APT) may make oral challenge superfluous in diagnosing children with food hypersensitivity., Objective: To investigate the clinical relevance of APT in predicting hypersensitivity to cow's milk and hen's egg in 486 unselected children 3 years of age., Method: The children were examined by APT, skin prick (SPT), histamine release (HR), and specific IgE followed by oral challenge when hypersensitivity to cow's milk or hen's egg was suspected., Results: Food hypersensitivity confirmed by oral challenge was 1.6% to hen's egg and 0.6% to cow's milk. No hypersensitivity to cow's milk or hen's egg was predicted by APT alone., Conclusion: APT could not predict food hypersensitivity not predicted by SPT, HR, or specific IgE. Thus, APT cannot be recommended in daily practice for the diagnosis of hypersensitivity to cow's milk and hen's egg in children 3 years of age.

Background: Previously published articles described a relationship between food-specific IgE and the outcome of food challenge in children with egg allergy. These investigations defined different levels of predictive values in different study populations and thus pointed toward the possibility of a certain level of specific IgE to egg white predicting a positive outcome in food challenge., Objective: The purpose of this study was to determine the utility of specific IgE in estimating threshold level to predict a positive outcome in food challenge., Methods: Fifty-six children were evaluated for egg allergy by titrated oral challenges. Sera were analyzed for specific IgE to egg white in 56 patients by using the Magic Lite test and 32 of 56 patients also by the CAP test. Values of specific IgE to egg white were compared to the outcome of challenges and the threshold level., Results: The diagnostic level of specific IgE predicting clinical reactivity in this population with greater than 95% certainty was identified as 10.8 standardized units/mL (Magic Lite) and 1.5 kilounits of allergen-specific IgE/L (CAP), respectively. We found no significant relationship between the specific IgE concentration (egg white) and the challenge threshold level., Conclusion: Although the specific IgE concentration correlated to a positive outcome in food challenge, there was no significant relationship between the quantification of specific IgE and the challenge threshold level. Therefore the standardized food challenge still remains the gold standard in the diagnosis of food allergy.