The European standard series. European Environmental and Contact Dermatitis Research Group (EECDRG)

Advancing the understanding of allergic contact dermatitis: from pathophysiology to novel therapeutic approaches

Allergic contact dermatitis (ACD) is a common inflammatory skin disease that, especially when the condition becomes chronic, has a high impact on the quality of life and represents a significant disease burden. ACD represents a type IV delayed-type hypersensitivity reaction that is triggered by contact with an allergen in previously sensitized individuals through the activation of allergen-specific T cells. In the acute phase, it is characterized by eczematous dermatitis, which presents with erythema, edema, vesicles, scaling, and intense itch. Non-eczematous clinical forms are also described (lichenoid, bullous, and lymphomatosis). Lichenification is the most common clinical picture in the chronic phase if the culprit allergen is not found or eliminated. ACD can be associated with both occupational and non-occupational exposure to allergens, representing approximately 90% of occupational skin disorders along with irritant contact dermatitis. Patch testing with suspected allergens is required for a diagnosis. Metals, especially nickel, fragrance mix, isothiazolinones, and para-phenylenediamine, are the most commonly positive allergens in patients patch tested for suspected ACD. The treatment goal is to avoid contact with the culprit agent and use topical and/or systemic corticosteroid therapy.

Patch testing with the European baseline series and 10 added allergens: Single-centre study of 748 patients

BACKGROUND

The European baseline series (EBS) of contact allergens is subject to change. An allergen is considered for inclusion when routine patch testing of patients with suspected contact dermatitis results in ≥0.5% prevalence rate.

OBJECTIVES

We aimed to determine the frequency of sensitizations to 30 EBS allergens and 10 locally added allergens. Additionally, we assessed the strength and evolution of reactions to all tested allergens and co-reactivity of additional allergens.

METHODS

Patch testing with our baseline series of 40 allergens was done in 748 consecutive adults. Tests were applied to the upper back and removed by patients after 48 h. Readings were done on Day 3 (D3) and D6 or D7 (D6/7). Positive reactions fulfilled the criteria of at least one plus (+) reaction. A retrospective analysis was done.

RESULTS

Eight allergens not listed in the EBS had ≥0.5% prevalence rate (i.e., cocamidopropyl betaine, thiomersal, disperse blue mix 106/124, 2-bromo-2-nitropropane-1,3-diol, diazolidinyl urea, propylene glycol, Compositae mix II and dexamethasone-21-phosphate), and 16.6% of positive reactions would have been missed without D6/7 readings.

CONCLUSION

We propose further studies to evaluate whether cocamidopropyl betaine, disperse blue mix 106/124, 2-bromo-2-nitropropane-1,3-diol, diazolidinyl urea and Compositae mix II need to be added to the EBS.

Patch Testing Pearls

Dermatitis is one of the most common illnesses encountered by healthcare providers and the causes are numerous. Contact dermatitis is the form of dermatitis resulting from contact with the environment, and it may be either irritant or allergic in nature. Patch testing has been the gold standard for diagnosis of allergic contact dermatitis since its formal description over 100 years ago by Jadassohn. While this diagnostic tool may seem simple to us today, there are numerous potential points for error that the practitioner must keep in mind. Patient selection, technique of patch test placement, allergen selection, patch test reading and interpretation, and patient management all must be considered. To simply apply a given set of test allergens indiscriminately and not be prepared to interpret the results accurately with patient education and management in mind would be a great failure. Conversely, with experience and the proper knowledge base some of the most complex dermatitis questions can be answered.

The Spanish standard patch test series: 2016 update by the Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC)

The Spanish standard patch test series, as recommended by the Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC), has been updated for 2016. The new series replaces the 2012 version and contains the minimum set of allergens recommended for routine investigation of contact allergy in Spain from 2016 onwards. Four haptens -clioquinol, thimerosal, mercury, and primin- have been eliminated owing to a low frequency of relevant allergic reactions, while 3 new allergens -methylisothiazolinone, diazolidinyl urea, and imidazolidinyl urea- have been added. GEIDAC has also modified the recommended aqueous solution concentrations for the 2 classic, major haptens methylchloroisothiazolinone and methylisothiazolinone, which are now to be tested at 200ppm in aqueous solution, and formaldehyde, which is now to be tested in a 2% aqueous solution. Updating the Spanish standard series is one of the functions of GEIDAC, which is responsible for ensuring that the standard series is suited to the country's epidemiological profile and pattern of contact sensitization.

European Society of Contact Dermatitis guideline for diagnostic patch testing - recommendations on best practice

The present guideline summarizes all aspects of patch testing for the diagnosis of contact allergy in patients suspected of suffering, or having been suffering, from allergic contact dermatitis or other delayed-type hypersensitivity skin and mucosal conditions. Sections with brief descriptions and discussions of different pertinent topics are followed by a highlighted short practical recommendation. Topics comprise, after an introduction with important definitions, materials, technique, modifications of epicutaneous testing, individual factors influencing the patch test outcome or necessitating special considerations, children, patients with occupational contact dermatitis and drug eruptions as special groups, patch testing of materials brought in by the patient, adverse effects of patch testing, and the final evaluation and patient counselling based on this judgement. Finally, short reference is made to aspects of (continuing) medical education and to electronic collection of data for epidemiological surveillance.

Occupational and non-occupational allergic contact dermatitis: a follow-up study

BACKGROUND/AIMS

The aim of this study was to obtain insight into the clinical course and prognosis of allergic contact dermatitis (ACD), including potential effects of genetic and environmental factors.

METHODS

Eighty-two patients with previously defined ACD acquired occupationally (OACD) or non-occupationally (NOACD) were patch retested and evaluated for the presence of persistent eczema, atopy and filaggrin mutations.

RESULTS

The crude risk for the persistence of a positive patch test (PT) reaction was 6.3 times higher (95% CI 3.63-11.0) for PT reactions assessed as '+++' compared to '++' reactions at the first PT. Among the categories of OACD, NOACD, age, gender, atopy, and the number of positive PT reactions at the first and second PT, only OACD (OR 10.0, 95% CI 1.95-51.2) and number of positive PT reactions at retesting (OR 3.85, 95% CI 1.57-9.44) were found to be predictors of persistent eczema.

CONCLUSIONS

Occupationally acquired contact allergy was emphasized as the most important factor in predicting poor prognosis of ACD.

Low frequency of filaggrin null mutations in Croatia and their relation with allergic diseases

Filaggrin gene (FLG) null mutations are considered associated with atopic dermatitis. This study was conducted to determine the prevalence of FLG null mutations R501X, 2282del4, R2447X and S3247X in the Croatian population and their role in the occurrence of allergic diseases including atopic dermatitis, allergic rhinitis, asthma and allergic contact dermatitis (ACD). Study enrolled 440 freshmen with defined allergic diseases by means of both present symptoms in International Study of Asthma and Allergies in Childhood questionnaire (relevant respiratory and/or skin symptoms) and markers of allergic sensitization (positive skin prick and/or patch test). FLG null mutations were successfully genotyped in 423 students of which 11 (2.6%) were carriers of FLG null mutation: 1/423 (0.2%) was heterozygous for R501X and 10/423 (2.4%) were heterozygous for 2282del4. No carriers of R2447X and S3247X mutations were identified. In wild-type FLG carriers (412 subjects), atopic dermatitis was present in 45 (11%), allergic rhinitis in 70 (17%) and allergic asthma in 29 (7%) students. Twenty-five of 393 (7%) patch-tested wild-type FLG carriers had ACD. Among 11 FLG null mutation carriers, four had one or more allergic diseases, and five had reported skin symptoms without defined allergic sensitization (positive skin prick test and/or patch test). FLG null mutations were not confirmed as a predictor of analysed allergic diseases, but were confirmed as an independent predictor of skin symptoms (OR 17.19, 95% CI 3.41-86.6, P < 0.001). Our results in general indicate a low frequency of FLG null mutations in the studied Croatian population supporting a theory of a latitude-dependent distribution of FGL null mutations in Europe, with a decreasing north-south gradient of R501X and 2282del4 mutation frequency. The relation between FLG null mutations and skin disorders was confirmed.

Reduced frequency of atopic dermatitis in quinoline-allergic patients: the 'hapten-atopy hypothesis'

BACKGROUND

While allergy to food proteins is almost exclusively found in association with atopy, it has been our experience that contact allergy to some contact allergens/haptens with both cutaneous and gastrointestinal exposures is reduced in atopic dermatitis (AD) patients as a group.

OBJECTIVE

To assess the contact allergy rates of two classes of antimicrobial haptens, one with both cutaneous and gastrointestinal exposures (quinolines) and one with only significant cutaneous exposure (aminoglycosides), with respect to the presence or absence of AD.

METHODS

Contact allergy rates to neomycin (aminoglycoside) and quinoline mix/clioquinol in patients attending the St John's Institute of Dermatology for diagnostic patch testing were retrospectively analysed; current AD and history of AD were noted.

RESULTS

In comparison to neomycin-allergic subjects, there was a highly significant negative association between quinoline contact allergy and current presence of AD (P = 0.0028); negative association between quinoline contact allergy and a history of AD did not reach significance (P = 0.07).

CONCLUSIONS

In comparison to an antimicrobial with no significant gastrointestinal exposure (neomycin), contact allergy to quinolines is negatively associated with the presence of AD. This is in contrast to food protein allergy, which is strongly associated with atopy. Possible explanations could include (i) confounding factors or (ii) AD patients are efficient at orally tolerizing haptens and inefficient at orally tolerizing proteins, secondary to their atopic status or (iii) oral tolerance of haptens antagonizes tolerance of food proteins and also leads to an immunological shift towards atopy (hapten-atopy hypothesis).

Retesting with the TRUE Test�in a population-based twin cohort with hand eczema ? allergies and persistence in an 8-year follow-up study

Population-based studies on contact allergy with retesting of individuals are infrequently performed. Variable degrees of persistence are reported when individuals with contact allergy are retested with years in between. The patch test results of 270 individuals tested in 2005-2006 are presented and the pattern and frequency of sensitization discussed. Persistence when compared with patch test results from 1997-1998 is reported. 270 twin individuals with and without hand eczema underwent patch testing with the TRUE Test((R)) (Mekos Laboratories AS, Hilleroed, Denmark) in 1997-1998 and again in 2005-2006 as part of a larger study. In 2005-2006, a total of 74 (27.4%) of the 270 individuals had at least 1 positive patch test and 20 (7.4%) of the 270 had 2. The frequency in men and women was 9/90 (10%) and 65/180 (36.1%), respectively. The frequency of contact allergy in individuals with and without hand eczema was 59/185 (31.3%) and 15/85 (17.6%), respectively. The most prevalent contact allergies were to nickel, thiomersal, and fragrance mix I. All together, 74% of the positive reactions were reproduced. The frequency of contact allergy in this population-based cohort with hand eczema was comparable with previous reports. Persistence of contact allergy after many years was confirmed.

20 Years of standard patch testing in an eczema population with focus on patients with multiple contact allergies

Results of standard patch tests performed with the same methodology in one centre are rarely available over a large time span. This gives the unique opportunity to study not only prevalence but also persistency of contact allergy and characterize subpopulations. The objectives were to investigate sensitivity rates and persistencies of patch test results and characterize patients with multiple contact allergies. A 20-year retrospective database-based study of 14 998 patients patch tested with the European Standard Series was performed. 34.5% were sensitized, primarily women. Sensitivity to nickel was most frequent and least frequent to mercaptobenzothiazole, N-isopropyl-N-phenyl-p-phenylenediamine and benzocaine. Yearly proportion of negative, mono/double-allergic, and multiple-allergic cases remained stable. Persistency of positive reactions was high for para-phenylenediamine, Cl(Me)isothiazolinone, and primin and poor for paraben mix. 5.1% were multiple allergic, primarily women, and 90% got diagnosed by the first test. Frequency of multiple allergies increased with age. More multiple- than mono/double-allergic patients were tested multiple times. Persistency and sensitivity rates in a Danish eczema population are provided and are useful for decisions regarding the standard series. Patients with multiple contact allergies are typically elderly women who might have long-lasting and hard-to-treat eczema. Cumulative environmental exposure seems necessary to develop multiple allergies.

Occupational allergic contact dermatitis from azithromycin in pharmaceutical workers: a case series

BACKGROUND

Reports on hypersensitivity reactions to azithromycin associated with therapy or occupational exposure have been rare.

OBJECTIVES

A case series describing clinical characteristics, diagnostic pathways and risk factors in occupational allergic contact dermatitis (ACD) caused by azithromycin in pharmaceutical workers is presented.

PATIENTS/METHODS

7 out of 21 pharmaceutical workers exposed to powdered intermediate and final substances in azithromycin synthesis were referred with workplace-related skin and respiratory symptoms. They all underwent diagnostic procedure involving medical history and examination, patch testing with standard allergens and azithromycin, prick testing with inhalatory allergens and total immunoglobulin E measurement.

RESULTS

Airborne ACD caused by azithromycin was established in 4 examined workers with positive patch test to azithromycin. 2 workers additionally had positive patch test to intermediate substances. Occupation-related symptoms of urticaria, rhinoconjunctivitis, laryngitis and/or dyspnoea were described in additional 2 workers without clearly positive patch test to azithromycin. 2 atopic workers had a shorter asymptomatic period between the beginning of the exposure to azithromycin and occurrence of skin symptoms than non-atopics (2-3 months versus 1-3 years, respectively).

CONCLUSIONS

Our results suggest that daily manipulation with powdered azithromycin and intermediates is a main route of sensitization. Besides contact sensitization, other possible workplace-related azithromycin hypersensitivity reactions are indicated.

Greater allergenicity of topical ketoprofen in contact dermatitis confirmed by use

The use of topical non-steroidal anti-inflammatory drugs (NSAIDs) is very popular in spite of their doubtful efficacy and high number of generally not serious, but preventable, adverse effects, especially photoallergy. The allergenic potential of different topical NSAIDs was determined by performing a retrospective observational study of the period 1996-2001 and comparing the cases of allergy and photoallergy with the use of each topical NSAID. The diagnoses were obtained from a review of the clinical records of patch/photopatch testing carried out in the dermatology departments of 2 public hospitals in Bizkaia (Spain). The use of the different topical NSAIDs was obtained from invoices sent to the National Health System and the Reporting odds ratio (ROR) and Proportional reporting ratio (PRR) disproportionality estimates of the FEDRA database of the Spanish Pharmacovigilance System. A total of 139 contact reactions to topical NSAIDs were found with ketoprofen being responsible for 28% of the allergies and 82% of the contact photoallergies in spite of not being the most used topical NSAID (third in the ranking, diclofenac was the first). The ROR for ketoprofen was 3.9 (2.4-6.4) and the PRR 3.4 (2.1-5.5), thus confirming the possibility of a warning signal. The results support the need for regulatory action on topical ketoprofen.

Occupational peri-ocular contact dermatitis due to sensitization against black rubber components of a microscope

A 24-year-old female working in the Department of Pathology of a University Hospital developed an acute peri-ocular eczema clearly being related to her daily work at the microscope. Patch testing revealed delayed type hypersensitivity against the black rubber mix, N-isopropyl-N'-phenyl paraphenylenediamine, N-cyclohexyl-N'-phenyl paraphenylenediamine and the rubber ring situated on the ocular of the respective microscope. This is the first report, to our knowledge, on peri-orbital allergic contact eczema because of sensitization with rubber components of a microscope.

Allergic contact dermatitis to quaternium 15 in a moisturizing lotion

A 56-year-old nurse from a rural area presented with a 12-month history of hand dermatitis. She had previously been patch tested by a local medical practitioner with the thin-layer rapid-use epicutaneous test, which had shown allergies to quaternium 15 and formaldehyde. After testing, she was prescribed methylprednisolone aceponate 1 mg/g cream by the medical practitioner, but was not informed that quaternium 15 is contained in the Microshield moisturizing lotion she was using at work. When her dermatitis persisted, she saw a dermatologist, who advised her to avoid the Microshield moisturizing lotion, and use a waterless hand cleanser on return to work. The diagnoses were firstly allergic contact dermatitis from quaternium 15 in the moisturizing lotion, and secondly irritant contact dermatitis from nursing work. This case highlights both the presence of quaternium 15 in a product commonly used in health-care settings in Australia, and the importance of offering informed, appropriate advice to patients following patch testing.

Monitoring the European standard series in 10 centres 1996-2000

A 5-year retrospective study of the frequency of sensitization to the 25 allergens of the European standard series (ESS) was conducted in 10 centres in 8 European countries. Included were the results of 26 210 patients. The range in sensitivities differed moderately between the centres. Combining results of different centres and drawing conclusions on incidences can be done only with great care. The information on the ranking of the allergens and their sensitization incidence in the clinics are useful for decisions on the future composition of the standard series. The ESS is still a valid screening tool, and no substances should be deleted.

Orofacial reaction to methacrylates in dental materials: a clinical report

This clinical report presents an unusual response of acute gingivostomatitis caused by contact sensitivity to the methacrylate compounds present in a dental restorative material.

The British standard series of contact dermatitis allergens: validation in clinical practice and value for clinical governance

BACKGROUND

All centres use an empirically determined set of 'standard' test allergens for patch testing that contain the commoner environmental sensitizers. Objectives To assess the validity of the British standard series of 12 allergens used in addition to the 23 already in the European standard series.

PATIENTS AND METHODS

Results for 3062 consecutive patients patch tested in seven centres across the United Kingdom during the year 2000 were analysed.

RESULTS

The additional allergens from the British series and positive rates were: methyl dibromoglutaronitrile 2.4%, carba mix 1.6%, tixocortol pivalate 1.5%, ethylenediamine 1.3%, cetearyl alcohol 0.8%, 2-bromo-2-nitropane-1,3-diol 0.8%, diazolidinyl urea 0.7%, chlorocresol 0.6%, budesonide 0.6%, fusidic acid 0.5%, imidazolidinyl urea 0.5%, and chloroxylenol 0.4%. The allergens with the lowest positive rate in the European standard series were primin at 0.6% and isopropyl-phenyl-para-phenylenediamine at 0.4%.

CONCLUSIONS

The 12 allergens in the British series should continue being tested as a standard addition to the European series within the U.K. The collection of data in this manner to allow comparisons between centres shows differences that reflect selection criteria and interpretation of results, and offers a useful tool for audit and clinical governance. Testing fewer than 1 : 2150 population may indicate underprovision of service. Similarly, rates of sensitization for nickel contact allergy above 26% and for fragrance mix above 16% (the upper 95% confidence intervals) should stimulate inquiry into the reasons behind this.

Evaluation of the Skin and Cancer Foundation standard series in the diagnosis of allergic contact dermatitis

The use of a standard series of 37 allergens was evaluated in a retrospective study of 817 consecutive patients seen between April 1988 and January 1993 at the Skin and Cancer Foundation, Melbourne, Australia. Of the 316 patients with clinically relevant patch test results, 134 (42%) reacted to an allergen in the standard series alone, while an additional 122 (39%) had reactions to allergens in both the standard and supplementary series. The remaining 60 (19%) patients reacted only to allergens in the supplementary series. These data suggest that the use of our standard series alone will detect about 80% of allergic contact dermatitis cases, but that many of these may be insufficiently evaluated. Use of supplementary allergen testing in a specialised clinic is recommended for patients who may have allergic contact dermatitis.

Patch testing in a British district general hospital

The results of patch testing in 753 patients attending a dermatology clinic in a British district general hospital over the period 1993-96 are presented. The frequency of positive reactions, and of the relative frequency of common allergens is broadly comparable to series published from specialist contact clinics. This study suggests that nonspecialist dermatology clinics can carry out routine patch testing adequately, although there are likely to be a number of cases which will require review in a specialist clinic or specialist advice.

Thoughts on sensitizers in a standard patch test series. The European Society of Contact Dermatitis

Patch testing is the predominant method of establishing contact allergy. The present patch test technique is the result of a continuous process of development and improvement since its first application in the late 19th century. The perfect patch test should give no false-positive and no false-negative reactions. The ideal patch test should also cause as few adverse reactions as possible, particularly no patch test sensitization. Even though the history and examination of a patient with suspected allergic contact dermatitis will give clues to possible sensitizers, it is not sufficient to patch test only with initially suspected sensitizers; unsuspected sensitizers used for patch testing frequently turn out to be the real cause of the dermatitis. Fortunately, a small number of substances are considered to account for the majority of delayed hypersensitivity reactions. Therefore, generally 20-25 test preparations consisting of chemically defined compounds, mixes of allergens, and natural and synthetic compounds, are grouped into a standard test series. The requirements to be fulfilled by a sensitizer in a standard patch test series are discussed in this article. A procedure of investigations is proposed before a sensitizer is included in a standard series.

The CXCR3 activating chemokines IP-10, Mig, and IP-9 are expressed in allergic but not in irritant patch test reactions

Differentiation between allergic and irritant contact dermatitis reactions is difficult, as both inflammatory diseases are clinically, histologically, and immunohistologically very similar. Previous studies in mice revealed that the chemokine IP-10 is exclusively expressed in allergic contact dermatitis reactions. In the present study, we investigated whether the mRNA expression of IP-10 and the related CXCR3 activating chemokines, Mig and IP-9 are also differentially expressed in human allergic contact dermatitis and irritant contact dermatitis reactions. Skin biopsies from allergic (13 cases) and sodium lauryl sulfate-induced irritant patch test reactions (13 cases), obtained 1-72 h after patch testing, were studied by means of an in situ hybridization technique. Results of chemokine mRNA expression were correlated with clinical scoring, histology, and immunohistochemical data including the proportion of inflammatory cells expressing CXCR3, the receptor for IP-10, Mig, and IP-9, and ICAM-1 and HLA-DR expression on keratinocytes. IP-10, Mig, and IP-9 mRNA were detected in seven of nine allergic contact dermatitis reactions after 24-72 h, but not in sodium lauryl sulfate-induced irritant contact dermatitis reactions. ICAM-1 expression by keratinocytes was only found in allergic contact dermatitis reactions and correlated with chemokine expression. Moreover, up to 50% of the infiltrating cells in allergic contact dermatitis expressed CXCR3, in contrast to only 20% in irritant contact dermatitis reactions. In conclusion, we have demonstrated differences in chemokine expression between allergic contact dermatitis and irritant contact dermatitis reactions, which might reflect different regulatory mechanisms operating in these diseases and may be an important clue for differentiation between allergic contact dermatitis and irritant contact dermatitis reactions.

An update of the risk assessment for methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) with focus on rinse-off products

Methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) has been widely used during the last 20 years for the preservation of aqueous systems in cosmetics, toiletries and in various industrial applications. MCI/MI has a broad spectrum of activity against fungi and bacteria at very low concentrations. The allergic contact potential of MCI/MI has been known for many years. This paper provides a review of pre-clinical and clinical experimental studies as well as experience from dermatology clinics worldwide. This forms the basis for an update of the risk assessment for the use of MCI/MI in rinse-off products. The scientific data indicate that the actual sensitization rate observed with a contact allergen is extremely dependent on dose and type of exposure. This review of the data leads to the conclusion that, under normal use conditions, within the current permitted/ recommended use concentrations for MCI/MI of up to 15ppm, the risk of primary sensitization from the use of rinse-off products is negligible, and elicitation of allergic contact dermatitis in MCI/MI-sensitized individuals rare, after exposure to MCI/MI-preserved rinse-off products.

Utility of a standard allergen series alone in the evaluation of allergic contact dermatitis: a retrospective study of 732 patients

BACKGROUND

Patch testing remains the standard for the diagnosis of allergic contact dermatitis. The validity and usefulness of a standard patch test allergen series has not been addressed adequately by previous studies.

OBJECTIVE

We sought to examine the utility of the standard allergen series as a sole screening tool in the diagnosis of allergic contact dermatitis.

METHODS

The charts of 732 patients referred for patch testing were reviewed for positive patch test results. The group of patients with positive reactions was stratified into two groups based on the clinical relevance of their reactions. These groups were subsequently analyzed to determine whether the reactions were to part of the standard series of allergens or to part of a supplementary group.

RESULTS

Of patients tested, 50% had a positive patch test. Of those, 221 (30%) had reactions deemed clinically relevant. Only 23% of patients with positive patch tests reacted to an allergen(s) in the standard series exclusively. When adjusted for clinical relevance, only 15.7% of patients were completely evaluated with the standard series of 20 allergens.

CONCLUSION

The standard allergen series of 20 allergens available in the United States is limited as a screening tool when used alone in the evaluation of patients with allergic contact dermatitis.

Proposal for a revised international standard series of patch tests

Worldwide, there are 3 major standard series of patch tests, the European, North American and Japanese, together presenting 32 allergens, the differences between them being the result of regional variation in allergen distribution as well as differences in dermatological opinion. We propose a "minimal" international standard series of 20 allergens, together with an "extended" international standard series of 14 allergens.

A proposed relevance scoring system for positive allergic patch test reactions: practical implications and limitations

A relevance scoring system for positive allergic patch test reactions is proposed. It refers to current relevance (CR) as well as past relevance (PR). The system was evaluated in adult patients between January 1 and June 30, 1996, and limited to 4 allergens: nickel sulfate, neomycin sulfate, epoxy resin and colophony. Certain methods available for increasing the accuracy of relevance were used in the present study. Practical implications and limitations of using a relevance scoring system are discussed.