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Background The common contact allergens may change over time as the environmental exposure changes. Objectives To identify the prevalence rates and changing trends of contact allergens in Taiwan over a 40-year period. Materials & methods The patch testing results of a referral centre from 1978 to 2018 were retrospectively reviewed. The study population was divided into four groups according to 10-year intervals. The prevalence rates of contact sensitization to each agent and the clinical relevance were analysed. For patients with positive reactions to relevant allergens, the occupations and sites of dermatitis were analysed. Results From 1978 to 2018, a total of 4005 patients underwent patch testing. Successively increasing trends of positive reactions to cobalt, fragrance mix I, and para-phenylenediamine (PPD) were found. Methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) was an emerging contact allergen. Hairdressers, cosmetologists, and aromatherapists became the occupations most commonly having positive reactions in the most recent 10 years. In the first two decades, the face and neck were the most commonly affected areas. Later, hands became the most commonly affected sites. Conclusions The prevalence rates of positive reactions to cobalt, fragrance mix I, and PPD increased successively. MCI/MI was an emerging contact allergen of special concern.

Introduction Azathioprine is a synthetic purine analogue derived from 6-mercaptopurine which acts by disrupting nucleic acid synthesis and interfering with T cell activation. It is effective in dermatology diseases related to the immune system. However, its side effects, including severe neutropenia, kept patients from using it. Mutations in thiopurine methyltransferase (TPMT) and inosine triphosphate pyrophosphohydrolase (ITPA) genes account for the major genetic polymorphism markers for azathioprine adverse risk factors in Caucasians, but not in Asians. The predictive value of the nucleoside diphosphate-linked moiety X motif 15 gene (NUDT15) has been studied in various diseases among different populations. The aim of our study was to determine the contribution of NUDT15 mutations in azathioprine-induced neutropenia in Han Chinese patients with dermatologic diseases. Methods The study enrolled all consecutive patients, older than 13 years old, with dermatological diseases currently treated orally with azathioprine in our clinic. Samples were also collected from patients with documented leukopenia in our prior study that examined the association between TPMT, ITPA, and neutropenia after informed reconsent. Complete blood count, differential count, and hepatic and renal function were checked regularly. The DNA samples for NUDT15 genotype were obtained from the patients. Results In total, we enrolled 56 patients (39 male, 17 female). The NUDT15 genotypes are mostly C/C (N = 36, 64.29%). Heterozygous variant (C/T) accounts for 30.36% (N = 17) and homozygous variant (T/T) accounts for 5.36% (N = 3). Among these patients, 15 patients (26.79%) developed neutropenia, including all three patients carry homozygous variant (T/T). The age-, sex-, and dose-adjusted risk of heterozygous variant compared to wild type is 9.383 (95% CI 1.32–66.96). Conclusions Pretreatment screening of NUDT15 might reduce the chance of azathioprine-induced neutropenia in Han Chinese patients with dermatologic diseases.

Acrylates are esters of acrylic acid, which are potent sensitizers that can cause occupational allergic contact dermatitis (ACD) in dental personnel. More recently, an increasing number of cases of both occupational and non-occupational ACD in beauty industry are observed. Here we present three cases of ACD to acrylate and its derivatives in both nail beauticians and do-it-yourself gel nail users due to exposure to nail cosmetics presenting with chronic hand eczema with severe pulpitis and even nail dystrophy with patch-test-confirmed diagnosis. Chemical analysis of commercial nail cosmetic products has been done in one of the patients and successfully identified 2-hydroxypropyl acrylate as the contact allergen. Keywords: Acrylic acid, Acrylate, Allergic contact dermatitis (ACD), Methacrylate, Nail cosmetic products

Background/Objective Since 2005, there has been a significant increase in contact allergy to methylisothiazolinon (MI)/methylchloroisothiazolinone (MCI) incidences in European countries, but there has been no documented large-scale studies of such incidences in Taiwan. Methods From 1987 to 2015, a total of 2590 patients received patch testing in our Contact Dermatitis Clinic. Analyzed were patients with positive reactions to MI/MCI (Kathon CG) in patch testing and with suspected allergy to MI/MCI. Results Among the total 2590 patients, 2388 received patch testing during 1987–2005, while 202 received patch testing during 2006–2015. Because Kathon CG was not routinely patch tested for all patients from 1987 to 2005, the incidence of contact allergy to MI/MCI was thus corrected to 3/145 (2.1%) for this time period. After 2005, there were 11 patients (11/202, 5.4%) who showed positive reactions to MI/MCI. Amongst the 14 patients who showed positive reactions to MI/MCI, 12 of them were females (85.7%). The majority of the lesions was located on the hands (10 patients, 71.4%), along with the face (3 patients, 21.4%). Interestingly, 6 patients (42.9%) who showed positive reactions to MI/MCI were associated with contact allergy to essential oils, and five of them were aromatherapists. Conclusion According to our study, the incidence of MI/MCI contact allergy in a referral center in Taiwan was 5.4%. A trend of increasing incidence of contact allergy to MI/MCI was noted after 2005, which is consistent with the findings in Europe. Allergic contact dermatitis to MI/MCI should be suspected in patients who have eczema on the hands and face, especially those who are aromatherapists.

Background/objective Contact dermatitis to topical medicaments is commonly encountered in daily practice of dermatologists. The incidence and ranking of common allergens in topical medicaments may vary depending on local prescription and self-medication behavior. The objective of this study is to investigate the clinical features and common allergens of contact dermatitis to topical medicaments in Taiwan. Methods From 1978 to 2005, a total of 3717 patients had been patch tested in our Contact Dermatitis Clinic. Any case with suspected contact allergy to topical medicaments receiving patch testing was included in this study. Results During this period, a total of 608 patients were included and 603 of them completed the patch tests. Of the 603 patch-tested patients, 397 (66%) were positive for at least one antigen, and all patch tests were negative in 206 (34%). Patients with positive patch testing were characterized by younger age and location on the limbs and skin folds, while sex and atopy were not different among the two groups. A total of 1076 positive reactions to identifiable medicaments or main ingredients were recorded in 397 patients with positive patch testing. Among these positive reactions, 701/1076 counts (65%) were read as relevant. Traditional herbal medicaments (50%), antiseptics (21%), vehicle ingredients (9%), antibiotics (8%), corticosteroids (2%), anesthetics (2%), and nonsteroidal anti-inflammatory drugs (1%) were the most common sensitizers in this study, and the common concomitant allergens were fragrance (52%) and metal (20%). Conclusion The results emphasized the special cultural consideration in Taiwanese patients with contact dermatitis to topical medicaments.

Background: Longitudinal melanonychia (LM) may occur as a result of nail apparatus melanoma. Knowledge of etiology plays an important role in the management of LM. Objectives: The study is aimed to compare the diagnosis of LM in different age groups. Methods: We collected 63 cases (45 adults and 18 children) with LM who underwent nail matrix biopsy or excision in a 21-year cohort and assessed their clinicopathological features. Results: Melanomas in adults and children were 40% and none, while nevi accounted for 15.6% in adults and 94.4% in children. There was a statistically significant difference between the average age at diagnosis for melanoma (54.5 ± 13.3 years) and nevus (15.2 ± 18.5 years). Logistic regression related the occurrence of melanoma to older ages with a relative risk of 1.2 compared to nevus, but no cutoffs between age groups could be defined between LM-associated nevus and melanoma. Conclusion: The adult group has a significantly higher risk of melanoma, while children with LM show mostly nonmelanoma etiologies. Tissue proof is more warranted in adult cases, and it is needed in selected cases of children with LM.