Positive Patch Test Research Articles

North American Contact Dermatitis Group Patch Test Results: 2017-2018.

Patch testing is an important diagnostic tool for assessment of allergic contact dermatitis (ACD). This study documented the North American Contact Dermatitis Group (NACDG) patch testing results from March 1, 2017, to December 31, 2018. At 14 centers in North America, patients with dermatitis were tested in a standardized manner with a screening series of 70 allergens and supplemental allergens as clinically indicated. Data were manually verified and entered into a central database. Descriptive statistics were estimated, and trends were analyzed using χ2 test. Overall, 4947 patients were tested. There were 3235 patients (65.4%) who had at least 1 positive reaction and 2495 patients (50.4%) had a primary diagnosis of ACD. Five hundred eighty-one patients (11.7%) had occupationally related dermatitis. There were 10,122 positive patch test reactions. Nickel remained the most commonly detected allergen (16.2%), followed by methylisothiazolinone 0.2% aqueous (15.3%) and methylchloroisothiazolinone/methylisothiazolinone 0.02% aqueous (200 ppm, 11.0%). Compared with the previous reporting periods (2015-2016 and 2007-2016), the proportion of positive reactions for the top 20 screening allergens statistically increased for only 1 allergen, propolis (3.4%; risk ratios = 2.05 [confidence interval = 1.66-2.54] and 1.82 [confidence interval = 1.57-2.11]).Four newly added allergen preparations, hydroperoxides of linalool (8.9%), benzisothiazolinone (7.3%), sodium metabisulfite (2.7%), and hydroperoxides of limonene (2.6%), all had a prevalence of greater than 2%. Approximately 1 (19.7%) in 5 tested patients had 1 or more clinically relevant reactions to an allergen not on the NACDG screening series; 13.2% of these were occupationally related. T.R.U.E. TEST (SmartPractice Denmark, Hillerød, Denmark) would have hypothetically missed 30% to 40% of reactions detected by the NACDG screening series. These results demonstrate the importance of a regularly updated screening allergen series. Methylisothiazolinone continues to be a significant allergen in North America. Patch testing with allergens beyond a screening tray is necessary for complete evaluation of occupational and non-occupational ACD.

The role of metal patch testing in evaluating patients for metallic prosthetic joint failure

BackgroundMetal allergy may be an uncommon cause of prosthetic joint failure. There exist little data on patch testing to metals in this context and its impact on outcomes of joint revision in these patients. ObjectiveTo explore the use and indications for metal patch testing in the evaluation of patients suspected of having metal allergy as a cause of failed joint replacements and to clarify the outcomes of patients revised with alternative metallic joints because of positive patch testing result. MethodsA retrospective analysis from January 2016 to April 2020 was completed on a patient cohort referred for evaluation of metal hypersensitivity. Charts were reviewed for age, biological sex, referring specialty, patch testing results, joint, revision status, and outcome measures. Biostatistical analysis and descriptive statistics were performed to determine patch testing performance and functional outcome trends among this patient cohort. ResultsThe sensitivity and specificity of patch testing, in general, are limited when evaluating patients with metallic joint replacements. However, the predictive value of testing seemed to improve with strongly positive patch testing results. Functional outcomes in patients when positive results were used to guide revision prosthesis revealed clinical improvement. ConclusionThe attribution of metal allergy or hypersensitivity as a cause of failure in metal prosthetic joint replacement remains unproven. Some patients with positive histories and patch testing results that were used to modify the implanted prosthesis had improved functional outcomes. These results suggest that patch testing may be useful in patients with history of metal sensitivity and prosthetic failure.

Legislative update: Regulating ingredients in personal care products

The prevalence of personal care product (PCP)-related dermatoses has increased over the last 20 years. The frequency of PCP-related allergen positive patch tests more than doubled between 1996 and 2016.1 Notably, many dermatologist-recommended shampoos, including prescription-strength and over-the-counter antidandruff shampoos and tar shampoos, contain formaldehyde releasers and other known allergens. PCP allergy has also been associated with lichen planopilaris and frontal fibrosing alopecia. In a study of 42 patients with lichen planopilaris/fibrosing alopecia, 76.2% had positive reactions to allergens in their PCPs used on the face and scalp, and allergen avoidance resulted in decreased scalp inflammation.

Contact dermatitis associated with preservatives: Retrospective analysis of North American Contact Dermatitis Group data, 1994 through 2016

Preservativesare often necessary components of commercial products. Large-scale North American studies on preservative allergy are limited. To evaluate demographics, positive patch test reactions (PPTRs), clinical relevance, and trends for preservatives tested by the North American Contact Dermatitis Group. We conducted a retrospective cross-sectional analysis of North American Contact Dermatitis Group patch testing results of preservatives from 1994 through 2016. A total of 50,799 patients were tested; 11,338 (22.3%) had a PPTR to at least 1 preservative. The most frequent reactions were to methylisothiazolinone 0.2% aqueous (aq) (12.2%), formaldehyde 2% aq (7.8%), formaldehyde 1% aq (7.8%), quaternium-15 2% petrolatum (pet) (7.7%), and methyldibromo glutaronitrile/phenoxyethanol 2% pet (5.1%). Paraben mix 12% pet (1%), iodopropynyl butylcarbamate 0.1% pet (0.4%), benzyl alcohol 1% pet (0.3%), and phenoxyethanol 1% pet (0.2%) had the lowest PPTRs. Linear regression analysis of preservatives tested showed that only methylchloroisothiazolinone/methylisothiazolinone 0.01% aq (parameter estimate, 0.42; 95% CI, 0.17-0.66; P<.005) had a significant increase in PPTRs over time. Collected variables are dependent on clinical judgment. Results may be prone to referral selection bias. This large North American study provides insight on preservative PPTRs and trends from 1994 through 2016.

Atopic skin diathesis rather than atopic dermatitis is associated with specific contact allergies.

The association of atopic dermatitis (AD) and allergic contact dermatitis has been a matter of considerable uncertainty. Study results range from lack of any association to increased sensitization for multiple allergens, but fail to identify consistent allergen associations. We studied a large patch test cohort of patients stratified by their atopic skin diathesis using the Erlangen Atopy Score (EAS), independent of active skin disease. Retrospective multi-center data analysis from five departments of dermatology in Germany with 4,509 patients. Patients were grouped as "no atopic skin diathesis" (n=2,165) and "atopic skin diathesis" (n=1,743), according to EAS. Significantly more individuals with atopic skin diathesis showed at least one positive patch test reaction to the baseline series compared to individuals without atopic skin diathesis (49.1% vs. 38.3%). In logistic regression analyses, atopic skin diathesis was associated with a significantly higher risk of sensitization to methylchloroisothiazolinone/methylisothiazolinone (OR 2.383) and methylisothiazolinone (OR 1.891), thiuram mix (OR 1.614), as well as nickel (OR 1.530), cobalt (OR 1.683), and chromium (OR 2.089). Atopic skin diathesis proved to be the most important intrinsic risk factor for contact sensitization to few, specific allergens. Past or present AD was a less relevant variable.

Iatrogenic allergic contact dermatitis in the (peri)anal and genital area.

Allergic contact dermatitis (ACD) from topical medication often occurs in occluded areas, for example, with wound treatment, but also in certain body locations, such as the anogenital area. To investigate the demographics and specific lesion location of patients with ACD from topical drugs applied onto the (peri)anal/genital area, and to identify the respective causal topical pharmaceutical products and ingredients involved. From January 2000 to December 10, 2018, 532 patients were tested with the baseline series, sometimes with additional series, and the topical medication used along with the ingredients. The relevant data were extracted from our electronic databases developed in-house. Forty-four patients (9%) out of 473 patients suffering from lesions in the (peri)anal/genital area had positive patch test results to topical drug preparations and/or their ingredients, sometimes in association with cosmetics for intimate hygiene. The most frequent sensitizing active principles were local anaesthetics and corticosteroids, while wool alcohols and to a minor extent benzoic acid were the most frequent culprits among the vehicle components and preservative agents, respectively. The local conditions (eg, occlusion, sweating, moist) in the anogenital area may favour skin sensitization to topical medication used to treat various skin diseases.

Patch Testing With Methylchloroisothiazolinone/Methylisothiazolinone Using a New Diagnostic Mix-A Multicenter Study From the International Contact Dermatitis Research Group.

In the early 1980s, a preservative containing a mixture of methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI) in a ratio of 3:1 was introduced. This mixture (mix) has been patch tested at 100 ppm (0.01%) worldwide and at 200 ppm (0.02%) in Sweden since 1986 and also in the European baseline series since 2014. A new aqueous mix of MCI 0.015% and MI 0.2% was compared with patch testing with the 2 aqueous baseline preparations of MCI/MI 0.02% and MI 0.2%. Four thousand three hundred ninety-seven patients with dermatitis in 12 International Contact Dermatitis Research Group dermatology departments from 3 continents were patch tested simultaneously with the 3 preparations. The frequency of positive patch tests to the allergens varied between 0% and 26.7% in the 12 test centers. The new mixture MCI/MI 0.215% in aqua (aq) detected significantly more patients with MCI/MI allergy than both MCI/MI 0.02% aq (P < 0.001) and MI 0.2% aq (P < 0.001) alone and combined. The results favor replacing the preparations MCI/MI 0.02% aq and MI 0.2% aq with the mixture MCI/MI 0.215% aq in the International Contact Dermatitis Research Group baseline series.

Improving povidone-iodine and iodine preparations for patch testing.

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. To investigate different preparations for iodine patch tests and to assess their clinical relevance with repeated open application tests (ROATs). 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. 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. 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.

The prevalence of contact hypersensitivity in patients with oral lichen planus.

IntroductionOral lichen planus (OLP) is a chronic autoimmune inflammatory disease with an unknown aetiology and a higher prevalence in women. Oral lichenoid lesions both clinically and histologically resemble oral lichen planus and are often associated with contact allergy to dental materials.AimTo investigate the prevalence of delayed hypersensitivity reactions in patients with OLP and to identify the most common allergens that may exacerbate the disease.Material and methodsTwenty patients diagnosed with OLP and undergoing treatment in the Gerodontology and Oral Pathology Department of the Poznan University of Medical Sciences were enrolled in the study. The subjects underwent a detailed oral examination consisting of anamnesis and a clinical evaluation by a qualified dentist, while an assessment of the skin and skin appendages was carried out by a dermatologist. Patch testing was performed using the Polish Baseline Series and Dental Screening Series.ResultsFifty percent of the examined patients displayed positive patch test reactions. A total of 18 allergic reactions were revealed, but only four appeared during the first test. The most common allergens were found to be nickel, gold, and a fragrance mix. Only 1 patient had a positive reaction to more than three allergens.ConclusionsThere seems to be a high contact reaction rate in patients with oral lichen planus, which is not related to contact with synthetic dental materials. However, further investigations on a larger population with the introduction of additional tests administered 7 days after exposure are required to confirm the effects of delayed hypersensitivity reactions on patients with OLP exacerbation.

Clinical, occupational and allergological profile of 455 patients with occupational contact dermatitis: A 5-year study from a tertiary care center of North India

Objectives:To evaluate clinical and occupational profile and common allergens in patients with occupational contact dermatitis (OCD).Materials and Methods:The records of 455 (M:F 2:1) patients aged 18-85 years with allergic contact dermatitis were analyzed retrospectively. The diagnosis of OCD and patterns of dermatitis were defined by standard criteria. Indian standard series comprising 20 allergens and when suspected patient's own products were patch tested by Finn chamber method as per European Society of Contact Dermatitis guidelines and relevance of positive results was defined clinically.Results:Airborne contact dermatitis (27.7%), acral dermatitis (14.1%), hand dermatitis (12.9%), acrofacial dermatitis (12.7%), and facial dermatitis (10.5%) were the common patterns. Agriculturists (51.2%), homemakers (27.9%), office workers (24.6%), and construction workers (4.6%) comprised the majority. Positive patch test results in 58% cases were from parthenium (31.7%), p-paraphenylenediamine (PPD) (22.9%), nickel (16%), fragrance mix (11%), potassium dichromate (10.7%), cobalt (7.6%), and mercaptobenzothiazole (4.9%). Hair colorants, shoe chips, and shaving cream also produced relevant positive reactions. Parthenium, PPD, fragrance mix, and potassium dichromate in agriculturists; nickel, parthenium, PPD, fragrance mix, and potassium dichromate in women, and potassium dichromate and parthenium in construction workers elicited the most positive reactions. PPD and hair colorants elicited positive reaction mainly in office workers.Conclusions:The agriculturists, homemakers, and construction workers have OCD most frequently. Parthenium in farmers, potassium dichromate in construction workers, nickel in women, and PPD in office workers were the major contact allergens. The study is limited by its retrospective design, small number of patients, and limited number of patch test allergens.

Comparative evaluation of steroid sensitivity in various dermatoses with control group through histopathological examination and patch testing

Background: Topical corticosteroids are widely used for treating various dermatoses. People have been self-medicating them for fungal infections, pigmentary disorders, and for many other dermatoses. This overzealous and irrational use of corticosteroid makes individuals susceptible for its adverse effects. Aim: The aim of this study was to evaluate steroid sensitivity in various dermatoses. Materials and Methods: Patch testing with Indian standard series and corticosteroid series was performed in sixty subjects where thirty patients were cases and thirty were controls. Histopathological examination and As it is (ASIS) were done only for the case group. Patches were applied on the back for 48 h and reading was done on day 2, day 4, and day 7 according to the International Contact Dermatitis Research group grading. Results: The maximum cases were in the age group of 20–30 years (33.3%) while 31–40 years was the most common age range (50%) among controls. Among the case group, 60% were male and 40% were female. Maximum patients affected in the case group were homemakers (36.7%) followed by laborers (13.3%). The case group showed 16.7% positive patch test reactions while none were positive in the control group. Thiomersal was positive in 13.3% of cases and neomycin in 3.3% of cases. ASIS was negative in all cases. Thiomersal is commonly used as a preservative in topical medicaments, cosmetics, and vaccines. Conclusions: Steroid sensitivity is hard to diagnose clinically, thereby causing difficulty in managing such cases. Patch test is a noninvasive gold standard procedure without major adverse effects and helps in treating the dermatoses with appropriate class of corticosteroid by avoiding the suspected allergen.

Contact dermatitis: An important consideration in leg ulcers.

The prevalence of chronic wounds is increasing with the aging population, with 1% to 2% of the worldwide population experiencing leg ulcers and positive patch tests reported in up to 75% of this population. With the introduction of modern dressings and compression therapies, clinicians should be cognizant of the potential risk of contact dermatitis in patients with leg ulcers. Contact dermatitis (both allergic and irritant) to wound products may present as maceration, pain, and overall impaired wound healing. Herein, we review the literature on contact dermatitis to wound-care products.

Machine-learning–driven biomarker discovery for the discrimination between allergic and irritant contact dermatitis

Contact dermatitis tremendously impacts the quality of life of suffering patients. Currently, diagnostic regimes rely on allergy testing, exposure specification, and follow-up visits; however, distinguishing the clinical phenotype of irritant and allergic contact dermatitis remains challenging. Employing integrative transcriptomic analysis and machine-learning approaches, we aimed to decipher disease-related signature genes to find suitable sets of biomarkers. A total of 89 positive patch-test reaction biopsies against four contact allergens and two irritants were analyzed via microarray. Coexpression network analysis and Random Forest classification were used to discover potential biomarkers and selected biomarker models were validated in an independent patient group. Differential gene-expression analysis identified major gene-expression changes depending on the stimulus. Random Forest classification identified CD47, BATF, FASLG, RGS16, SYNPO, SELE, PTPN7, WARS, PRC1, EXO1, RRM2, PBK, RAD54L, KIFC1, SPC25, PKMYT, HISTH1A, TPX2, DLGAP5, TPX2, CH25H, and IL37 as potential biomarkers to distinguish allergic and irritant contact dermatitis in human skin. Validation experiments and prediction performances on external testing datasets demonstrated potential applicability of the identified biomarker models in the clinic. Capitalizing on this knowledge, novel diagnostic tools can be developed to guide clinical diagnosis of contact allergies.

Can We Separate Oral Lichen Planus from Allergic Contact Dermatitis and Should We Patch Test? A Systematic Review of Chronic Oral Lichenoid Lesions.

This systematic review summarizes characteristics and treatment outcomes of dental amalgam-associated oral lichenoid lesions (OLLs) and oral lichen planus (OLP). Embase and MEDLINE were searched for original studies on OLLs or OLP associated with dental amalgam. Data extraction was completed from 44 studies representing 1855 patients. Removal of amalgam restorations led to complete resolution in 54.2% (n = 423/781), partial resolution in 34.8% (n = 272/781), and no resolution in 11.0% (n = 86/781) of the patients with OLLs, whereas complete resolution occurred in 37.1% (n = 72/194), partial resolution in 26.3% (n = 51/194), and no resolution in 36.6% (n = 71/194) of the patients with OLP. For patients with OLLs, 91.6% of the patients with positive patch tests and 82.9% with negative patch tests had improvement with removal of amalgam, whereas for patients with OLP, 89.2% of the patients with positive patch tests and 78.9% with negative patch tests had improvement with removal of amalgam. Our results suggest improvement occurs, regardless of patch testing status.

Contact Dermatitis From Gum Mastic (Pistacia lentiscus) and Gum Storax (Liquidambar styraciflua) in Mastisol-Allergic Patients.

Mastisol Liquid Adhesive is widely used on the skin, especially after surgical procedures. It contains gum mastic, gum storax, methyl salicylate, and ethanol. The aims of the study were to review our experience patch testing patients allergic to Mastisol and to assess coreacting substances. We identified 18 patients who were allergic to Mastisol. Most of these had a history of postoperative or cardiac electrode dermatitis and underwent patch testing with multiple surgically related substances, including ingredients of Mastisol, compound tincture of benzoin, and fragrance-related ingredients and botanicals. Among Mastisol-allergic patients, 13 (72%) of 18 were allergic to gum mastic, whereas 7 (44%) of 16 were allergic to gum storax. There was frequent coreactivity with various fragrance-related materials, including Majantol, Styrax benzoin, Myroxylon balsamum, Myroxylon pereirae, propolis, and others. Two gum mastic-allergic patients had positive patch tests with hydroperoxides of linalool and several other linalool-containing essential oils. As gum mastic contains linalool, it may explain some gum mastic reactions. Among patients without a history of postoperative contact dermatitis, 1 (0.4%) of 250 was patch test positive for gum mastic. This patient had allergic contact dermatitis from fragrances, so the gum mastic reaction was likely a true-positive relevant reaction.

Patch Testing: The Patient Experience.

Data regarding patient-reported symptoms during patch testing are limited. To provide frequency of symptoms (pain, sleep difficulty, medication need, site itching, itch elsewhere, and worsening rash) experienced by patients undergoing extensive patch testing and to determine association of these symptoms with patient characteristics. This was a retrospective chart review of patients who underwent patch testing at a tertiary referral, contact dermatitis clinic over 15 months. Demographics, number of patches placed, patch location(s), and number of reactions (total and ++/+++) were extracted by chart review. Frequency of symptoms reported on a questionnaire administered at the 48-hour (48H) and final (F) visits was tabulated, and associations were evaluated using χ2 and Fisher exact tests. Six hundred forty-one patient records were accessed. The most common symptom was patch site itching (48H, 77.4%; F, 76.5%). Frequency of pain and sleep difficulty were significantly higher at 48H compared with F (P < 0.0001). Worsening of rash was significantly higher at F compared with 48H (P < 0.0001). The number of patches was significantly associated with all symptoms except sleep difficulty (P ≤ 0.0141). Patch location was significantly associated with pain, medication need, itch elsewhere, and worsening rash but not sleep difficulty or site itch (P ≤ 0.0257). The number of reactions (total and ++/+++) was significantly associated with all symptoms except itch elsewhere (total P ≤ 0.0316; ++/+++: P ≤ 0.0445). Most patients reported symptoms during patch testing, most commonly itching (at patch site and elsewhere), sleep difficulty, and need for medication. The number of positive patch test reactions (total and ++/+++) was the most common characteristic associated with the symptoms.

Positive Patch Test Reactions to Carba Mix and Thiuram Mix: The North American Contact Dermatitis Group Experience (1994–2016)

BACKGROUND/OBJECTIVE This study characterizes concomitant reactions to carba mix (CM) and thiuram mix (TM) in a large North American population. Because thiurams and dithiocarbamates have structural similarity, concomitant reactions are expected. METHODS The 1994-2016 North American Contact Dermatitis Group data were analyzed. Patients with a final reaction interpreted as allergic to either CM or TM were included. RESULTS A total of 49,758 patients were tested to both CM and TM. A total of 3437 (6.9%) had positive reactions to CM and/or TM including the following groups: CM+ only (n = 1403, 40.8%), TM+ only (n = 1068, 31.0%), or both (n = 966, 28.1%). A total of 47.5% of TM+ patients were positive to CM and 40.8% of CM+ patients were positive to TM. Male sex, occupationally related dermatitis, and hand involvement were significantly more common in individuals positive to CM and/or TM as compared with those who were negative (P < 0.0001). More than 80% of CM+/TM+ reactions were currently relevant. Gloves were the most common source of CM and TM; clothing and footwear were also frequent. CONCLUSIONS Carba mix and TM remain important, clinically relevant allergens. Although significant concomitant reaction frequency was demonstrated, more than half of the patients reacting to either CM or TM would have been missed if both had not been tested, underscoring the importance of testing to both.

Patch Testing of Mercaptobenzothiazole and Mercapto Mix: The North American Contact Dermatitis Group Experience, 1994-2016.

Mercapto compounds are a category of rubber accelerators that may cause allergic contact dermatitis. This study characterizes patch test reactions to mercaptobenzothiazole (MBT) and mercapto mix (MM) in a large North American population. The 1994-2016 North American Contact Dermatitis Group screening series data were analyzed. Patients with allergic reactions to either MBT or MM (mercapto+) were included. The following characteristics were analyzed: strength of reaction, clinical and occupational relevance, coreactivity with other rubber accelerators, and sources of exposure. A total of 49,795 patients were tested to mercapto compounds from 1994 to 2016; 633 (1.3%) had positive reactions to MBT and/or MM. The frequency to both MBT and MM significantly decreased over time (P < 0.0001). Mercapto+ patients were significantly more likely to be male, have occupationally related skin disease, and report involvement of the hands and/or feet (P < 0.0001). They were significantly less likely to have face, scalp/ears/neck, or trunk involvement (P ≤ 0.0001). There was significant coreactivity with carba mix (23.4%) and thiuram mix (32.5%). Mercaptobenzothiazole and MM reactions were frequently clinically (81.7% and 83.5%, respectively) and occupationally relevant (29.8% and 33.4%, respectively). Gloves were the most common source (31.3% and 30.9%, respectively). Patch test positivity to mercapto compounds significantly decreased from 1994 to 2016 but remains clinically and occupationally relevant.

Contact allergy to polyhexamethylene biguanide (polyaminopropyl biguanide).

BackgroundPolyaminopropyl biguanide (INCI name) and polyhexamethylene biguanide (PHMB) are polymeric biguanides. PHMB is a broad‐spectrum antimicrobial substance used as a preservative in many products. Due to our limited knowledge on PHMB contact allergy frequency and the fact that cases of allergic contact dermatitis to PHMB might be missed, we have included PHMB as a screening allergen since 2016.ObjectiveTo report the prevalence of positive patch test reactions to PHMB as a screening allergen in patients with suspected allergic contact dermatitis.MethodsA retrospective analysis of 1760 patch tested patients from July 2016 to December 2018 was performed. Polyaminopropyl biguanide 2.0% aqua was included in the extended Malmö baseline series during the study period.ResultsOf all patients, 1204 (68.4%) were female. Positive patch test reactions were reported in 19 patients (1.1%). The most common sites of lesions were face, head, and neck (52.6%). There was a significant correlation between concomitant reactions to PHMB and other cosmetic‐related allergens.ConclusionThe prevalence of positive reactions to PHMB was higher than that previously reported. Patch testing with PHMB should be performed in patients with dermatitis who have lesions on the face, head, and neck.

The erythema Q-score, an imaging biomarker for redness in skin inflammation.

Physician rating of cutaneous erythema is central to clinical dermatological assessment as well as quantification of outcome measures in clinical trials in a number of dermatologic conditions. However, issues with inter‐rater reliability and variability in the setting of higher Fitzpatrick skin types make visual erythema assessment unreliable. We developed and validated a computer‐assisted image‐processing algorithm (EQscore) to reliably quantify erythema (across a range of skin types) in the dermatology clinical setting.Our image processing algorithm evaluated erythema based upon green light suppression differentials between affected and unaffected skin. A group of four dermatologists used a 4‐point Likert scale as a human evaluation of similar erythematous patch tests. The algorithm and dermatologist scores were compared across 164 positive patch test reactions. The intra‐class correlation coefficient of groups and the correlation coefficient between groups were calculated. The EQscore was validated on and independent image set of psoriasis, minimal erythema dose testing and steroid‐induced blanching images. The reliability of the erythema quantification method produced an intra‐class correlation coefficient of 0.84 for the algorithm and 0.67 for dermatologists. The correlation coefficient between groups was 0.85. The EQscore demonstrated high agreement with clinical scoring and superior reliability compared with clinical scoring, avoiding the pitfalls of erythema underrating in the setting of pigmentation. The EQscore is easily accessible (http://lab.rockefeller.edu/krueger/EQscore), user‐friendly, and may allow dermatologists to more readily and accurately rate the severity of dermatological conditions and the response to therapeutic treatments.