Multicenter 1-month follow-up study of the patch-test reaction to the gold sodium thiosulfate of the TRUE Test and its association with piercings and dental metal history.

BACKGROUND: There is controversy over late and long-lasting reactions to gold sodium thiosulfate (GST). OBJECTIVES: To study the GST patch-test reaction by observing the application site after 1 month, and to clarify the relevance of GST sensitization by piercings and dental metals. PATIENTS: A retrospective analysis was performed on 746 patients (143 male; 603 female) who were patch tested using GST of the TRUE Test. We conducted a questionnaire on the presence of piercings or dental metals in these patients. RESULTS: The GST positive rate was 27.9% at day (D)3 and/or D7 and 40.3% up to the 1-month reading. The positive rate was significantly higher in female patients and increased with age. Sixty-two percent of cases with a positive reaction at D7 continued to show a positive reaction after 1 month. Eleven percent of cases with a negative reaction at D3 and D7 showed a late reaction. Both piercings and dental metals were related to gold sensitization. CONCLUSIONS: The GST of the TRUE Test had a high positive and low false-negative rate. The 1-month reading after the patch test was important for identifying late reactions. Piercing history and dental metal were associated with gold sensitization.

A multi-institutional joint study of contact dermatitis related to hair colouring and perming agents in Japan.

BACKGROUND: In Japan, allergic contact dermatitis caused by hair colouring agents is a considerable problem for those occupationally exposed and also for consumers. Over the last 20 years, p-phenylenediamine (PPD) has been a common allergen, with ∼7% positive patch test reactions. OBJECTIVES: To investigate which ingredients caused allergic contact dermatitis related to hair dye and perming solutions in Japan, to assess whether PPD is suitable for screening for hair dye allergy, and to propose allergens for a Japanese hairdresser series. METHODS: We selected 19 hair cosmetic allergens, including PPD, Bandrowski's base, cysteamine HCl, and ammonium thioglycolate. Altogether 203 patients (26 males and 177 females) with suspected contact allergy to hair colouring or perming solutions at 14 hospitals in Japan were included. RESULTS: The highest prevalence of positive reactions (35.1%) was for PPD. p-Methylaminophenol and o-aminophenol were often positive, both in the PPD-positive and in the PPD-negative patients. Moreover, cysteamine HCl often yielded positive test reactions. CONCLUSIONS: PPD is insufficient to diagnose contact allergy caused by to hair dyes. We recommend 13 allergens to be included in a Japanese hairdresser series.

Quantitative evaluation of patch test reactions: a comparison between visual grading and erythema index image analysis.

BACKGROUND/AIMS: The interpretation of patch test reactions may vary between examiners. As test results are graded, an issue also arises when differing degrees of erythema are placed in the same grade. The purpose of this study was to quantitatively evaluate the degree of erythema in patch tests using image analysis and to study the usefulness of this method by comparing it with visual grading. METHODS: A total of 121 Japanese patients were patch tested with various materials. At 48 h, digital photographs of the patch test areas were taken, in addition to a visual evaluation by dermatologists. Digital images of the areas were converted to erythema index (EI) images using image processing and both EI and ΔEI (the difference between the patch test site and adjacent normal skin) values of the patch test sites were compared with the corresponding visual grades. RESULTS: An excellent linear correlation (r=0.95) was found between ΔEI and visual grades, although EI also significantly correlated with visual grades. There were significant differences (P<0.0001-0.05) between the mean ΔEI values of any two adjacent visual grades. CONCLUSION: ΔEI values derived from image processing appear to be suitable for the quantitative evaluation of erythema in patch tests. This method may be helpful in overcoming the subjectiveness of visual evaluation and for training non-experts in patch testing.

Optimal patch application time in the evaluation of skin irritation.

We investigated the optimum application for evaluating skin irritation response by using samples of irritants commonly used as additives in cosmetics and other common household products. We studied 47 volunteers (16 men and 31 women). We selected three types of surfactant, one moisturizer, one anti-infective agent and one oil solution. Using Finn chambers on Scanpor tape, we performed the patch test. A total of 0.015 mL of each sample was applied to the Finn chamber. For liquids, circular filter paper was soaked in 0.015 mL of the sample. Samples were placed on the upper back of participants, and closed for 4, 24 or 48 h. A patch application time of 24 h is sufficient to detect primary skin irritation from irritants in cosmetics and other common household products. In addition, we found that skin irritation reactions were strongest at 24 h after patch removal and that the reaction tended to be weaker at 48 h after patch removal. Patch testing to evaluate irritants should be performed by means of a 24-h patch test with a follow-up reading at 24 h after patch removal. An application time of 24 h places less of a burden on patients than a 48-h patch test.