Irritant contact dermatitis (ICD) is a nonspecific skin inflammation caused by irritants, leading to itch and pain. We tested whether differential responses to histamine-dependent and -independent pruritogens can be evoked in ICD induced by sodium lauryl sulfate (SLS). An ICD mouse model was established with 5% SLS in acetone versus a vehicle topically applied for 24 h to the cheek. Site-directed itch- and pain-like behaviors, occurring spontaneously and in response to mechanical, thermal, and chemical stimuli (histamine, ß-alanine, BAM8-22, and bradykinin) applied to the cheek, were recorded before (day 0) and after irritant removal (days 1, 2, 3, and 4). Skin inflammation was assessed through visual scoring, ultrasound, and measurements of skin thickness. SLS-treated mice exhibited hyperalgesia-like behavior in response to mechanical and heat stimuli on day 1 compared to the controls. SLS mice exhibited more spontaneous wipes (pain) but not scratching bouts (itch) on day 1. Pruritogen injections caused more scratching but not wiping in SLS-treated mice compared to the controls. Only bradykinin increased wiping behavior compared to saline. SLS-treated mice developed noticeable erythema, scaling, and increased skin thickness on days 1 and 2. SLS induced cutaneous inflammation and behavioral signs of spontaneous pain and itching, hyperalgesia to mechanical and heat stimuli and a chemical algogen, and enhanced itch response to pruritogens. These sensory reactions preceded the inflammation peak and lasted up to two days.

Incontinence-associated dermatitis (IAD) is an irritant contact dermatitis from prolonged contact with urine or faeces, which can significantly impact patient comfort and quality of life. The identification of prognostic factors for the development of IAD has the potential to enhance management, support preventive measures and guide future research. The objective of this systematic review was to summarize the empirical evidence of prognostic factors for the development of IAD. This study included prospective and retrospective observational studies or clinical trials that described prognostic factors associated with IAD. There were no restrictions on setting, time, language, participants or geographical regions. Exclusion criteria included reviews, editorials, commentaries, methodological articles, letters to the editor, cross-sectional and case-control studies, and case reports. Searches were conducted from inception to April 2024 on MEDLINE, CINAHL, EMBASE and the Cochrane Library. The studies were assessed by two independent reviewers using the QUIPS and the CHARMS-PF for data extraction. A narrative synthesis approach was employed due to study heterogeneity and using the \'vote counting based on direction\' method and the sign test. The overall certainty of evidence was assessed using adapted GRADE criteria. The review included 12 studies and identified 15 potential predictors. Moderate-quality evidence suggests that increased stool frequency, limited mobility and friction/shear problems are risk factors for IAD development. Female sex, older age, vasopressor use and loose/liquid stool are risk factors supported by low-quality evidence. Increased stool frequency, limited mobility and friction/shear problems seem to be risk factors for the development of IAD. There is insufficient evidence to support the predictive validity of female sex, older age, loose/liquid stool and vasopressor use. There is substantial methodological variability across studies, making it challenging to make comparisons. Large-scale cohort studies in different settings that incorporate our review findings should be conducted in the future.

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BACKGROUND: Mainly women work as foot care specialists (FCS). They are at risk to develop occupational dermatitis (OD).
OBJECTIVE: The objective of this study is to describe the contact sensitisation pattern of female FCS with OD.
METHODS: In a retrospective study, patch test and clinical data collected by the Network of Departments of Dermatology (IVDK) from 2008 to 2022 were analysed. Data of 116 female FCS with OD were compared with data of 13 930 female patients with OD working in other professions and 78 612 female patients without OD.
RESULTS: Hand dermatitis (93.1%) was significantly more common and face dermatitis (0.9%) significantly less common in female FCS with OD compared to other female patients with or without OD. Frequent suspected allergen sources were disinfectants, gloves, leave-on and nail cosmetics. Occlusion and wetness were important co-factors. The most common diagnoses were irritant contact dermatitis (26.7%) and allergic contact dermatitis (21.6%). No sensitisation to any of the baseline series allergens was significantly more frequent in female FCS with OD than in the two control groups. However, sensitisations to allergens which FCS are abundantly exposed to, including fragrances, preservatives, rubber ingredients and disinfectants, were most common.
CONCLUSIONS: FCS should be aware of the OD risk and prevention should be promoted.

BACKGROUND: Machine learning (ML) offers an opportunity in contact dermatitis (CD) research, where with full clinical picture, may support diagnosis and patch test accuracy.
OBJECTIVE: This review aims to summarise the existing literature on how ML can be applied to CD in its entirety.
METHODS: Embase, Medline, IEEE Xplore, and ACM Digital Library were searched from inception to February 7, 2024, for primary literature reporting on ML models in CD.
RESULTS: 7834 articles were identified in the search, with 110 moving to full-text review, and six articles included. Two used ML to identify key biomarkers to help distinguish between allergic contact dermatitis (ACD) and irritant contact dermatitis (ICD), three used image data to distinguish between ACD and ICD, and one used clinical and demographical data to predict the risk of positive patch tests. All studies used supervision in their ML model training with a total of 49 704 patients across all data sets. There was sparse reporting of the accuracy of these models.
CONCLUSIONS: Although the available research is still limited, there is evidence to suggest that ML has potential to support diagnostic outcomes in a clinical setting. Further research on the use of ML in clinical practice is recommended.

The differential diagnosis of dermatoses in the axillae is broad. Contact dermatitis-both irritant and allergic-represents common etiologies. Axillary contact dermatitis can develop following exposure to a variety of irritants and/or allergens. Frequently implicated sources include deodorants, antiperspirants, detergents, soaps, and clothing. Fragrance, a ubiquitous ingredient within these products, as well as metals and dyes, are common causes of contact dermatitis. Clinical assessment, bedside diagnostic techniques, histopathology, and patch testing can aid in the diagnosis and help inform management directions.

OBJECTIVE: Electrical stimulation (ES) is a widely used technique in the medical field for various purposes. The effect of ES on several skin properties has been investigated; however, its effect on skin vulnerability to irritants remains unknown. This study aimed to investigate the effects of ES application on skin vulnerability to external irritants.
METHODS: An experimental study on 12 healthy male subjects (Mean ± SD, 22.9 ± 3.6 years) who completed the study. The subjects were free of skin abnormalities in the volar aspect of both forearms. Three areas were allocated to each forearm and marked as areas 1, 2, and A in the treated forearm, and areas 3, 4, and B in the control forearm. ES was applied to the volar aspect of the treated forearm for 30 min three times a week, for 2 weeks. The effect of ES on skin vulnerability was investigated using 5% and 0.5% sodium lauryl sulfate (SLS) patches applied to both treated and control forearms. The skin response to irritants was evaluated using transepidermal water loss (TEWL) and a visual erythema score 24 h after patch removal.
RESULTS: Compared to the control forearm, ES increased skin permeability and erythema in response to external irritants (SLS), as measured by the visual analog score (Z = 2.75, p = 0.006) and TEWL (p < 0.05), respectively.
CONCLUSIONS: ES escalates skin reactions to low concentrations of irritant substances, such as SLS, in the area between the two electrodes. This emphasizes the use of this substance, and similar irritants should be avoided in areas treated with ES.

BACKGROUND: Distinguishing between allergic and nonallergic forms of Contact Dermatitis (CD) is challenging and requires investigations based on patch-testing. Early detection of allergy biomarkers in active CD lesions could refine and simplify the management of CD patients.
OBJECTIVE: To characterize the molecular signatures of active CD lesions.
METHODS: We studied the expression of 12 allergy biomarkers by qRT-PCR in active lesions of 38 CD patients. Allergic CD (ACD) was diagnosed based on patch test (PT) results and exposure assessment. Molecular signatures of active lesions, as well as positive PT reactions, were compared with those of reference chemical allergens and irritants.
RESULTS: Nineteen of the 38 CD patients reacted positively upon patch-testing and exposure assessment confirmed ACD diagnosis for 17 of them. Gene profiling of active CD lesions revealed 2 distinct molecular patterns: patients harboring signatures similar to reference allergens (n = 23) or irritants (n = 15). Among the 23 patients with an \"allergy signature,\" we found the 17 patients with confirmed ACD, while no culprit allergen was identified for the 6 other patients. Interestingly, the 15 patients without biomarker induction had negative PT, suggesting that they developed nonallergic CD reactions.
CONCLUSIONS: Molecular signatures from active skin lesions may help to stratify CD patients and predict those suffering from ACD.

BACKGROUND: Chronic hand eczema (CHE) is a highly prevalent, heterogeneous, skin disease that encompasses different aetiological and clinical subtypes. Severe CHE without atopic dermatitis has been associated with systemic inflammation; yet it remains unknown if specific CHE subtypes leave distinct, systemic, molecular signatures.
OBJECTIVE: To characterize the inflammatory plasma signature of different aetiological and clinical CHE subtypes.
METHODS: We assessed expression levels of 266 inflammatory and cardiovascular disease risk plasma proteins as well as filaggrin gene mutation status in 51 well-characterized CHE patients without concomitant atopic dermatitis and 40 healthy controls. Plasma protein expression was compared between aetiological and clinical CHE subgroups and controls both overall and according to clinical CHE severity. Correlation analyses for biomarkers, clinical and self-reported variables were performed.
RESULTS: Very severe, chronic allergic contact dermatitis (ACD) on the hands was associated with a mixed Type 1/Type 2 systemic immune activation as compared with controls. Circulating levels of Type 1/Type 2 inflammatory biomarkers correlated positively with clinical disease severity among CHE patients with ACD. No biomarkers were found, that could discriminate between aetiological subtypes, for example, between ACD and irritant contact dermatitis. Hyperkeratotic CHE showed a distinct, non-atopic dermatitis-like, systemic footprint with upregulation of markers associated with Type 1 inflammation and tumour necrosis factor alpha, but not Type 2 inflammation. Increased levels of CCL19 and CXCL9/10 could discriminate hyperkeratotic CHE from both vesicular and chronic fissured CHE, whereas no difference was found between the latter two subtypes.
CONCLUSIONS: Profiling of systemic biomarkers showed potential for identifying certain CHE subtypes. Peripheral blood levels of inflammatory biomarkers were associated and correlated with the clinical disease severity of chronic ACD on the hands, underlining that this is a systemic disease. We question whether hyperkeratotic CHE should be classified as eczema.

Jacquet erosive dermatitis (JED) is a rare, severe form of napkin dermatitis associated with friction and irritant exposure in the napkin area. The condition typically causes erosions and erythematous punched-out ulcerations. We present two cases of JED in infants associated with the use of a common brand barrier cream Curash. This appeared to present following a change of several active ingredients.