Patch testing with aluminium Finn Chambers could give false-positive reactions in patients with contact allergy to aluminium.

BACKGROUND: Earlier laboratory studies have shown that sodium tetrachloropalladate, Myroxylon pereirae, caine mix II, and palladium chloride trigger the release of aluminium (Al) from Finn Chambers (FC). OBJECTIVES: To investigate whether aluminium realease from FC could influence the diagnostic outcome of patch testing with FC. METHOD: A retrospective analysis of patch test results from 2010 to 2019 was performed. A two-sided Fisher's exact test was used to calculate any overrepresentation of contact allergy to Al among patients with positive reactions to sodium tetrachloropalladate, Myroxylon pereirae, caine mix II, and palladium chloride. RESULTS: A total of 5446 patients had been tested with FC during the study period. There was a significant overrepresentation of contact allergy to Al among patients with positive reactions to sodium tetrachloropalladate, Myroxylon pereirae, caine mix II, and palladium chloride. Patients with a strong Al allergy had significantly higher amounts of concomitant reactions to sodium tetrachloropalladate, Myroxylon pereirae, caine mix II, and palladium chloride compared to patients with weak Al allergy. These results were not seen for patients tested with Finn Chambers AQUA. CONCLUSION: In patients with contact allergy to Al, patch testing with Finn chambers could give false-positive reactions to sodium tetrachloropalladate, Myroxylon pereirae, caine mix II, and palladium chloride.

Optoacoustic mesoscopy shows potential to increase accuracy of allergy patch testing.

BACKGROUND: Differentiation between irritant and allergic skin reactions in epicutaneous patch testing is based largely on subjective clinical criteria, with the risk of high intraobserver and interobserver variability. Novel dermatological imaging using optoacoustic mesoscopy allows quantitative three-dimensional assessment of microvascular biomarkers. OBJECTIVES: We investigated the potential of optoacoustic imaging to improve the precision of patch test evaluation. METHODS: Sixty-nine test reactions and 48 healthy skin sections in 52 patients with suspected type IV allergy were examined using raster-scan optoacoustic mesoscopy. RESULTS: We identified biomarkers from the optoacoustic images. Allergic reactions were associated with higher fragmentation of skin vasculature than irritant reactions (19.5 ± 9.7 vs 14.3 ± 3.7 fragments/100 pixels2 ; P < .05), as well as lower ratio of low- to high-frequency acoustic signals (1.6 ± 0.5 vs 2.0 ± 0.6, P < .05). Allergic reactions graded "++" showed higher vessel fragmentation than reactions graded "+" (25.4 ± 13.2 vs 17.1 ± 6.5 fragments/100 pixels2 ; P < .05). A linear model combining the biomarkers fragmentation and frequency ratio could differentiate allergic from irritant test reactions with an area under the receiving operator characteristic curve of 0.80 (95% confidence interval 0.64-0.91), reaching a sensitivity of 81% and specificity of 63%. CONCLUSIONS: Optoacoustic mesoscopy shows potential to help in differentiating between allergic and irritant test reactions based on novel biomarkers that may reflect vasodilation, vessel tortuosity, and edema.

Thoughts on how to improve the quality of multicentre patch test studies.

Multicentre patch test studies (MPTSs) can contribute useful information for diagnostic and preventive measures. The aim of the present paper is to propose how to perform high-quality MPTSs. To this end, factors of significance for the patch test result are discussed with regard to the standardization and calibration of high-quality MPTSs. The 16 factors discussed are scored 0, 1, 2, or 3, depending on the relative importance of a particular factor for the patch test result. The total score of an MPTS allows it to be ranked as having doubtful, acceptable, high or excellent quality. A total score of 30 is possible. Depending on the total score the MPTSs are grouped into those with a doubtful, acceptable, high, and excellent quality. In conclusion, high-quality MPTSs can be performed and are facilitated if a guideline and check list are followed when the study is being planned. The scoring enables the calculation of a total score, which can be used for quality ranking.

[Should metal alloy discs be used for patch testing in suspected metal implant intolerance reaction?]. / DKG-Stellungnahme zur Epikutantestung von Metalllegierungsplättchen bei Verdacht auf Metallimplantat-Unverträglichkeit.

Intolerance reactions to metal implants may be caused by metal allergy. However, prior to implantation, patch testing should not be done in a prophylactic-prophetic approach. Pre-implant patch testing should only be performed to verify or exclude metal allergy in patients with a reported respective history. In the case of implant-in particular arthroplasty-related complications like, for example, pain, effusion, skin changes, reduced range of motion, or loosening, orthopedic-surgical differential diagnostics should be performed first. Allergological workup of suspected metal implant allergy should be done with the DKG baseline series which contains nickel-, cobalt- and chromium-preparations. Various studies assessing the usefulness of metal alloy discs for patch testing proved that this approach does not give reliable information about metal allergy. Positive patch test reactions to the discs cannot be assigned to a specific metal within the disc alloy components. Furthermore, availability of such metal discs might be an invitation to uncritical testing. Accordingly, due to lack of benefit in comparison to patch testing with standardized metal salt preparations, we do not recommend patch testing with metal alloy discs.

Novel metal allergy patch test using metal nanoballs.

BACKGROUND: Patch tests are often used in the clinical diagnosis of metal allergies. In currently available patch tests, high concentrations of metal salt solutions are used. However, diagnosis accuracy can be influenced not only by acute skin reactions to high concentrations of metal salt, but also by skin reactions to other components present in the patch or to pH changes. In this study, we developed Ni nanoparticles (termed "nanoballs") for use in patch-test solutions. FINDINGS: Highly soluble, spherical Ni nanoballs were prepared using plasma electrolysis. The Ni released from the nanoballs permeated through a dialysis membrane, and the nanoball-containing solution's pH was maintained constant. Ni ions were released slowly at low concentrations in a time-dependent manner, which contrasted the rapid release observed in the case of a commercial patch test. Consequently, in the new test system, reactions caused by high concentrations of metal salts were avoided. CONCLUSIONS: By exploiting the high specific surface area of Ni nanoballs, we obtained an effective dissolution of Ni ions that triggered Ni allergy in the absence of direct contact between the nanoballs and mouse skin. This novel patch system can be applied to other metals and alloys for diagnosing various types of metal-induced contact dermatitis.

Using a nonadherent transparent scribing sheet: tip for allergen location in pediatric contact dermatitis testing.

We discuss the use of a nonadherent transparent scribing sheet as a tool to aid in allergen location during patch testing in pediatric patients.

Stability of selected volatile contact allergens in different patch test chambers under different storage conditions.

BACKGROUND: Patch test preparations of volatile substances may evaporate during storage, thereby giving rise to reduced patch test concentrations. OBJECTIVES: To investigate the stability of selected acrylates/methacrylates and fragrance allergens in three different test chambers under different storage conditions. METHODS: Petrolatum samples of methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (2-HEMA), 2-hydroxypropyl acrylate (2-HPA), cinnamal and eugenol in patch test concentrations were stored in three different test chambers (IQ chamber™, IQ Ultimate™, and Van der Bend® transport container) at room temperature and in a refrigerator. The samples were analysed in triplicate with high-performance liquid chromatography. RESULTS: The decrease in concentration was substantial for all five allergens under both storage conditions in IQ chamber™ and IQ Ultimate™, with the exception of 2-HEMA during storage in the refrigerator. For these two chamber systems, the contact allergen concentration dropped below the stability limit in the following order: MMA, cinnamal, 2-HPA, eugenol, and 2-HEMA. In the Van der Bend® transport container, the contact allergens exhibited acceptable stability under both storage conditions, whereas MMA and 2-HPA required cool storage for maintenance of the limit. CONCLUSION: The Van der Bend® transport container was the best device for storage of samples of volatile contact allergens.

Is it possible to characterize objectively sensitive skin?

BACKGROUND/PURPOSE: Sensitive skin is a subject of intense research work. However, its contours have not been defined and properly investigated so far. The aim of this work was to characterize objectively the consumers of cosmetic products, which referred skin susceptibility to several agents or conditions. METHODS: Twenty-four healthy female volunteers, mean age 38.9+/-13 years were recruited. The volunteers were fully informed about the study having previously expressed their consent, and were grouped in to I: individuals without any skin sensitivity complaint and II: individuals with self-reported sensitive skin to regular contact with household cleaning products. Sodium lauryl sulphate was used as a 'provocative' agent and it was applied on the back of the volunteers' hands, as an occlusive patch for 24 h. After the patch removal (30 min, 7 and 14 days), the variables erythema, transepidermal water loss, stratum corneum hydration and blood perfusion were measured. RESULTS: No evidence of a statistical difference was found between the biomechanical behaviour of the skin of the two groups. CONCLUSION: The results of our study did not enable us to establish a clear discrimination between sensitive and non-sensitive skin, which once again underlines the subjective nature of this condition.

Comparison of three different techniques for application of water solutions to Finn Chambers®.

BACKGROUND: With regard to contact allergy, the dose of a sensitizer per unit skin area is an important factor for both sensitization and elicitation, and therefore a known amount/volume of test preparation should be applied at patch testing. OBJECTIVES: To compare three different techniques for the application of aqueous solutions to Finn Chambers, in order to determine the precision and accuracy of each technique when the recommended 15 µl volume is applied. METHODS: Four technicians applied formaldehyde 1.0% aq. (wt/vol) and methylchloroisothiazolinone/methylisothiazolinone 200 ppm (wt/vol) in sets of 10 onto Finn Chambers, with three different techniques: (i) micro-pipetting; (ii) dripping the solutions; and (iii) dripping the solutions followed by removal of excess solution with a soft tissue. Assessment of the variations was performed with the use of descriptive data. The ability to apply the exact amount was assessed by Fisher's exact test by categorizing each application as in or out of the range 12-18 µl. RESULTS/CONCLUSIONS: The micro-pipette technique had the best accuracy and precision, as well as the lowest inter-individual variation. The technique in which excess solution was removed had good precision, but failed in the application of the defined amount, i.e. 15 µl.

A Novel Device that Reduces Preparation Times and Precision Mass Error in Patch Testing for Allergic Contact Dermatitis.

BACKGROUND: Patch test preparation for evaluation of allergic contact dermatitis is traditionally a slow process with inherent errors. OBJECTIVE: A novel device, referred to as a syringer, designed to dispense 10 unique petroleum-based haptens simultaneously, significantly reduces preparation time and increases the precision of the mass dispensed per well. METHODS: The syringer was custom designed and "printed" through the use of a 3-dimensional printer with a polylactic acid plastic medium. RESULTS: The syringer dispensed 10 haptens significantly (P < 0.05) faster: 6.9 seconds on average, compared with 29.6 seconds by the traditional method. The syringer demonstrated a significantly (P < 0.05) lower average deviation of each strip's per-well mass average compared with the traditional method. CONCLUSIONS: In practice, this syringer is ideal for preparing patient-ready patch tests in quantities of 2 identical strips or more.

Pre-testing in hair dye users: an assessment of the Colourstart system.

To avoid adverse reactions to allergenic ingredients, manufacturers recommend "sensitivity testing" prior to use of hair dyes. However, there is no standardised method and the recommendation is often not followed. We assessed the ability of a standardised test system from one manufacturer (Colourstart, a small skin surface water-slide transfer containing p-phenylenediamine (PPD)) for its ability to elicit a reaction in those with a previously diagnosed contact allergy to PPD, the main hair dye allergen. Thirty volunteers with diagnosed PPD allergy (10 each of 3+, 2+ and 1+) were assessed with the Colourstart system according to the manufacturer's instructions. Responses were recorded after 48h exposure. Colourstart identified 100% of those with a 3+ reaction to the diagnostic patch test, 80% of the 2+ reactors and just 10% of the 1+ reactors. Thus, Colourstart successfully identified those individuals with the greatest sensitivity to PPD, who might therefore be at risk of a severe reaction if they dyed their hair. It also identified 83% of those who reported a severe/very severe history of hair dye adverse reaction. However, its proper use and interpretation are necessary if those consumers most at risk are to have the information necessary to avoid serious adverse reactions to hair dyes.

Visible light photopatch testing of common photocontactants in female filipino adults with and without melasma: a cross-sectional study.

BACKGROUND: Although consistently associated with sun exposure, melasma is common among sun-shy Filipino women who generally prefer to have lighter skin, use skin lighteners, regularly practice sun avoidance, and are more exposed to indoor lights. OBJECTIVE: To determine presence/absence of photocontact dermatitis in melasma/no-melasma patients using photopatch testing (PhPT) with standard photocontactants and an indoor visible light (VL) source. DESIGN: Cross-sectional study: random population of 40 female patients aged 30-55 years, 20 with and 20 without melasma. The PhPT included 67 photocontactant allergens: 59 from Chemotechnique Diagnostics (24 fragrance, 22 North American photopatch, 13 plants) and 8 cosmetic allergens from Skin Sciences Laboratory Inc. (Pasig, Philippines) in sets of paired test patches. One of the pairs was irradiated with a 500-watt tungsten halogen lamp as the VL source; the other was the nonirradiated control. The standard protocols of the North American Contact Dermatitis Group (NACDG) was used to examine the nonirradiated control patches after 48 and 72 hours, the DAPT (German/ Austrian/ Swiss Photopatch Study Group) was used to examine the VL-irradiated patches, and both protocols were used to interpret relevance of the readings as to the presence or absence of contact dermatitis (CD) or photocontact dermatitis (PhCD). RESULTS: Fifty-five percent of patients in the melasma group (N = 11/20) had 29 positive (+) PhPT reactions to VL-irradiated allergens (11 fragrances, 11 North American, 7 plants). In the no-melasma group, none had (+) PhPT. This association is highly significant (P = 0.00 using 2-tailed Fischer's exact test), such that compared to a (-) PhPT, a (+) PhPT has 12.67 times more likelihood to develop melasma (P = 0.05: 1.402-114). All 29 (+) PhPT were decrescendo type, replaced by pigmentation observed up to 7 days suggesting phototoxic reactions, and all had (+) clinical relevance establishing phototoxic low-energy VL-PhCD. CONCLUSION: Melasma worsens with sun exposure, but this study shows that the low energy of artificial indoor VL is enough to react with photocontactants followed by a pigmentation response that may account for its clinical appearance as a mostly noninflammatory slowly evolving facial pigmentation.

Dispelling the myths behind pediatric patch testing-experience from our tertiary care patch testing centers.

Allergic contact dermatitis is now known to be a common problem in pediatric populations, accounting for up to 20% of all dermatitis seen in children. Seminal studies conducted over the past decade have demonstrated a prevalence rate in the range of 25% to 60% of children referred for epicutaneous patch testing. This patch test procedure is generally accepted as the gold standardin vivo technique to diagnose allergic contact dermatitis. However, the overwhelming majority of research studies to date have been conducted on adult populations. Increasingly, pediatric patients are undergoing patch test procedures with techniques that have been standardized and optimized almost exclusively in adults. With this article, we hope to emphasize common misconceptions and pitfalls encountered with this approach. In addition, we hope to stimulate research interest in this field so as to determine the optimum patch test conditions and techniques for children.

Use of the cytosensor microphysiometer to predict results of a 21-day cumulative irritation patch test in humans.

The cytosensor microphysiometer (mu phi) was investigated as a rapid, relatively inexpensive test to predict performance of skin cleansing wipes on the human 21-day cumulative irritation patch test (21CIPT). It indirectly measures metabolic rate changes in L929 cells as a function of test article dose, by measuring the acidification rate in a low-buffer medium. The dose producing a 50% reduction in metabolic rate (MRD50), relative to the baseline rate, is used as a measure of toxicity. The acute toxicity of the mu phi assay can be compared to the chronic toxicity of the 21CIPT, which is based largely on the exposure of test agents to the epidermal cells, resulting in damage and penetration of the stratum corneum leading to cell toxicity. Two series of surfactant-based cleansing wipe products were tested via the mu phi assay and 21CIPT. The first series, consisting of 20 products, was used to determine a prediction model. The second series of 38 products consisted of routine product development formulas or marketed products. Comparing the results from both tests, samples with an MRD50 greater than 50 mg/ml provided a 21CIPT score consistent with a product that performs satisfactorily in the market. When the MRD50 was greater than 78 mg/ml, the 21CIPT score was usually zero. The mu phi may be more sensitive than the 21CIPT for ranking minimally irritating materials. The mu phi assay is useful as a screen for predicting the performance of a wet wipes formula on the 21CIPT, and concurrently reduces the use of animals for safety testing in a product development program for cleansing wipes.

[Study on patch test reagent for titanium].

Recently, allergy to titanium has been reported. However, the patch test reagent for titanium is not standardized yet. The form and density of the patch test reagent for titanium was changed and examined in a group of normal subjects and a group with skin disease. The following conclusions were obtained. 1. A reagent which was composed of pure titanium powder and vaseline was not preferable because its form was a stimulant. 2. If the form of the titanium powder was not sharp even though it was not spherical, it did not cause a stimulated reaction. 3. It is suggested that TiCl4 0.1% is preferable as a patch test reagent for titanium.