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Background: Irritant contact dermatitis (ICD) is caused by the acute locally toxic effect of a strong irritant, or the cumulative exposure to various weaker physical and/or chemical irritants. Objectives: To describe the characteristics of patients with ICD in the population patch tested in the European Surveillance System on Contact Allergies (ESSCA; www.essca-dc.org) database. Methods: Data collected by the ESSCA in consecutively patch tested patients from January 2009 to December 2018 were analyzed. Results: Of the 68 072 patients, 8702 were diagnosed with ICD (without concomitant allergic contact dermatitis [ACD]). Hand and face were the most reported anatomical sites, and 45.7% of the ICD was occupational ICD (OICD). The highest proportions of OICD were found in metal turners, bakers, pastry cooks, and confectionery makers. Among patients diagnosed with ICD, 45% were found sensitized with no relevance for the current disease. Conclusions: The hands were mainly involved in OICD also in the subgroup of patients with contact dermatitis, in whom relevant contact sensitization had been ruled out, emphasizing the need for limiting irritant exposures. However, in difficult-to-treat contact dermatitis, unrecognized contact allergy, or unrecognized clinical relevance of identified allergies owing to incomplete or wrong product ingredient information must always be considered. [ABSTRACT FROM AUTHOR]

Background: The use of disinfectants is part of the everyday life of people, especially in the medical profession. During the coronavirus disease 2019 (COVID-19) pandemic, the use of disinfectants continues to increase and is of fundamental importance in infection control. Objectives: To determine the frequency of sensitization and the value of patch testing to didecyldimethylammonium chloride (DDAC) and the alcohols ethanol, 1-propanol, and isopropanol. Methods: Clinical patch test data of 145 patients with suspected contact allergy to disinfectants were retrospective analysed. Results: Among the 145 patients patch tested with the different alcohols, only one nurse was detected with a possible allergy to 1-propanol. Additional patch testing in 84 patients with DDAC 0.05% resulted in five patients with weakly positive reactions only, without clinical relevance. Patch testing with DDAC 0.03% showed no positive reactions at all on day 3 readings. Conclusions: DDAC and alcohols are rarely responsible for allergic contact dermatitis. The accused products of the patients should be checked for other allergens and further additives with skin-irritating properties. Individual susceptibility and mishandling of the disinfectants should be considered. [ABSTRACT FROM AUTHOR]

Background: Allergy evaluation by patch testing with povidone‐iodine (PVP‐I) or iodine remains challenging, because current patch test preparations frequently lead to false‐positive or irritant skin reactions. Objectives: To investigate different preparations for iodine patch tests and to assess their clinical relevance with repeated open application tests (ROATs). Methods: We monocentrically analyzed 95 patients with suspected allergy to disinfectants in retrospect who underwent parallel iodine patch testing with four preparations: PVP‐I 2% aq., 5% aq., 10% aq., and iodine 0.5% pet. Results: In 27 of 95 patients (28.4%), we found positive reactions to one of the four test preparations. After ROATs in 22 of these 27 positively tested individuals, only one patient was diagnosed with iodine allergy. In contrast, 31 of 95 patients (32.6%) showed irritant or questionable patch test reactions on day 2 (D2) and/or D3 and/or D7 to one or more test preparations. Testing with PVP‐I 2% aq. resulted in the lowest number of doubtful skin reactions while detecting the single allergic patient. Conclusion: PVP‐I 2% aq. was found to be the optimal patch test preparation. In general, iodine allergy appears to be substantially overestimated, and positive patch test responses to iodine should prompt an urgent ROAT for confirmation before diagnosing iodine allergy. [ABSTRACT FROM AUTHOR]

Background: Studies on patch testing with workplace materials and evaluation of current occupational relevance of positive patch test reactions are scarce in patients with occupational dermatitis (OD). Objectives: To identify frequent sensitizations with occupational relevance and to determine the value of patch testing with workplace materials in OD patients. Patients and Methods: Results and clinical data of 654 patients with suspected OD patch tested between 2013 and 2017 were analysed. Results: Occupational allergic contact dermatitis was diagnosed in 113 (17.3%) patients. Mechanics had the widest range of occupational sensitizations. Sensitization to epoxy resin was rated occupationally relevant in almost all handicraft trades. Among positive patch test reactions to workplace products, those to water‐based metal working fluids and leave‐on cosmetic products were most frequent. Despite frequent testing, protective gloves only rarely elicited positive reactions. Preservatives and rubber compounds were most frequently identified as currently occupationally relevant. Conclusions: Rubber allergy is occupationally relevant especially in healthcare workers and cleaners. Generally, preservatives including formaldehyde releasers are important allergens in OD patients. Leave‐on cosmetic products must not be forgotten as allergen sources. Patch testing both workplace materials and standardized test preparations has a complementary value and is beneficial for the diagnostic work‐up of OD patients. Highlights: Patch testing of workplace materials and standardized test preparations has a complementary value in the diagnostic work‐up of occupational dermatitis patients.Mechanics should be patch tested in a broad fashion, including rubber, metal working fluids, epoxy resin systems, and leave‐on products.Epoxy resin systems exhibit current occupational relevance in almost all high‐risk professions of the handicraft sector. [ABSTRACT FROM AUTHOR]

Background: Filaggrin (Flg) and hornerin (Hrnr) share similar structural and functional features. Both proteins have been implicated as essential proteins for skin barrier maintenance. Loss‐of‐function mutations of these genes constitute a risk factor for atopic dermatitis and eczema‐related asthma. Furthermore, both FLG and HRNR protein levels are downregulated in patients with atopic dermatitis. Thus, mice deficient for Flg and Hrnr provide a novel model to study skin barrier impairment and the susceptibility for cutaneous inflammation. Methods: By using appropriate targeting vectors and breeding strategies, we established a homozygous FlgHrnr double‐deficient (FlgHrnr−/−) mouse model lacking both genes including the intergenomic sequence. Results: Neonates appeared normal, but developed a transient scaly phenotype with overall flaky appearance, but no overt skin phenotype in adulthood, thereby reflecting a subclinical barrier defect seen in humans. Structurally, FlgHrnr−/− mice displayed a markedly reduced granular layer and a condensed cornified layer. Functionally, FlgHrnr−/− mice showed permeability abnormalities and metabolic aberrations regarding the production of natural moisturizing factors (NMFs) in the stratum corneum. Surprisingly, although the immune system revealed no aberrations under steady‐state conditions, FlgHrnr−/− mice are predisposed to mount an allergic contact dermatitis, especially at hapten threshold levels eliciting allergic reactions. Conclusions: Together, our FlgHrnr−/− mouse model nicely reflects the epicutaneous sensitization susceptibilities and inflammatory reactions to environmental insults in humans with impaired skin barrier functions. [ABSTRACT FROM AUTHOR]