Atopie-Patch-Test mit Aeroallergenen und Nahrungsmitteln

The atopy patch test (APT), a patch test employing allergens known to elicit IgE-mediated reactions which is assessed by evaluating eczematous skin lesions after 24 h to 72 h, was developed as a diagnostic tool for characterizing patients with aeroallergen-triggered atopic eczema (AE, atopic dermatitis). Positive APT reactions are associated with allergen-specific T-cell responses. The specificity of APT is higher than the specificity of skin prick tests or RAST. More studies for the standardization of APT methods are necessary, especially with regard to food APT.     

Evaporimetiy in the differentiation of allergic, irritant and doubtful patch test reactions

Background/aims: The aim is to evaluate, using evaporimetry, the possibility of getting further information supporting clinical reading of allergic, irritant reactions and doubtful patch test reactions.
Methods: The investigation was carried out on 204 patients (182 female and 22 male, mean age 31.6 years), patch tested routinely as suspects of allergic contact dermatitis. We evaluated 326 reactions (203 allergic, 123 irritant or doubtful).
Results: Mean values pf TEWL were: for the positive allergic reactions, 7.21 (SD, 2.26) at 48 h, 15.77 (SD, 5.50) at 72 h; and for the irritant or doubtful reactions, 7.55 (SD, 1.72) at 48 h, and 5.77 (SD, 1.41) at 72 h. TEWL in the 2 reactions groups at 72 h was significantly different (p<0.01).
Conclusions: The study shows (i) concordance between the evaporimeter values and the visual score; (ii) at 72 h, the evaporimeter values are increased in the allergic reactions but not in irritant or doubtful reactions; (iii) evaporimetry in the differential diagnoses of patch test reactions was deemed useful.     

Gramineae pollen as trigger factors of atopic eczema: evaluation of diagnostic measures using the atopy patch test

After contact with grass pollen, seasonal exacerbations of eczematous skin lesions have been described in a subgroup of patients with atopic eczema (AE). Epicutaneous patch testing with aeroallergens (atopy patch test, APT) has been used to investigate these patients. We performed comparative APT in 79 patients with AE and 20 control subjects (14 non-atopic volunteers and six patients with grass pollen allergic rhinoconjunctivitis). Subjects were tested with grass pollen allergen extract in petrolatum and with unprocessed native dry pollen of Dactylis glomerata . Results after 48 h were compared with the patient's history, corresponding skin prick test and specific IgE. Fifteen of the 79 AE patients showed clear-cut eczematous reactions to unprocessed D. glomerata pollen; 14 of these had an elevated serum IgE to D. glomerata and 13 had a positive skin prick test. Twenty patients had a positive APT reaction to grass pollen allergen extract, including 12 of the D. glomerata reactive subjects ( P  < 0.001). Positive patch test reactions to D. glomerata were seen in 66.7% of cases with and 10.5% of patients without a predictive history of exacerbations during the pollen season. For the standardized extract, these percentages were 75% vs. 16.4% ( P  < 0.001). No side-effects were observed. Control subjects showed no positive reactions. We conclude that grass pollen preparations may be used to investigate trigger factors for eczematous skin lesions in a subgroup of patients with AE.     

COMPARATIVE STUDY OF 3H-THYMIDINE LABELLING OF THE DERMAL INFILTRATE OF SKIN ALLERGIC AND IRRITANT PATCH TEST REACTIONS IN MAN

The ³H-Thymidine (³HT) nuclear labelling index of “round” cells of the dermal infiltrate in allergic and irritant patch test reactions in man has been compared. The skin of 15 positive allergic patch test reactions (to different allergens) and of 15 positive irritant reactions (5 to croton oil, 5 to potassium hydroxide and 5 to white spirit) was biopsied 48 hours after the application of the chemical. Thin slices of each specimen were incubated for 60 min in the presence of ³HT. then fixed and prepared for light microscopy radioautography. Two thousand “round” cells of the infiltrate were counted in each specimen. The mean values of the ³HT labelling indices (±S.E.) were 2·91±0·18%, in the allergic group and 0·58 ± 0·06% in the irritant group. The difference between the 2 means was highly significant (P < 0.01). There was no significant difference between the labelling indices of the 3 irritants (P > 0.05). All the labelled cells were mononucleated. This method could be useful to differentiate clinically dubious allergic and irritant reactions.     

The atopy patch test: an increased rate of reactivity in patients who have an air-exposed pattern of atopic eczema

Summary In a subgroup of patients with atopic eczema (AE), eczematous skin lesions can he induced by epicutaneous testing with aeroallergens (the atopy patch test: APT). An increased frequency of positive APT has been found in AK patients showing a predictive lesional pattern affecting air-exposed skin areas. This study investigates the dose-response ofthe APT in two dilTerent patient groups with AE. Petrolatum preparations of house dust mite, cat dander and grass pollen allergens in four concentrations (500–10,000) protein nitrogen imits) were tested epicutaneously in 57 patients with AE. who were prospectively divided in two groups according to whether their AE pattern was with (group I) or without (group II) a predictive distribution. Sixty-nine per cent of patients in group I. and 39% in group II. had positive APT reactions (P = 0.02). The reactions in group I were elicitable with lower allergen concentrations (P = 0.03). A clinically recognizable subgroup of patients with AE showed increased cutaneous sensitivity to aeroallergens.     

Simultaneous sodium lauryl sulphate testing improves the diagnostic validity of allergic patch tests. Results from a prospective multicentre study of the German Contact Dermatitis Research Group (Deutsche Kontaktallergie-Gruppe, DKG)

Background There is evidence that a higher skin susceptibility may induce nonspecific erythematous or weak positive reactions to contact allergens in patch testing. Objectives To evaluate whether simultaneous application of sodium lauryl sulphate (SLS) along with diagnostic patch tests with contact allergens can provide information regarding skin irritability which may help to discriminate allergic from nonspecific irritant reactions to contact allergens. Methods Between July 2001 and June 2003, this prospective study collected patch test data of 5971 patients from 19 centres in Germany and Austria in the Information Network of Departments of Dermatology (IVDK). In addition to contact allergens (standard series and eight known ‘problematic’ allergens with a low reaction index and a high positivity ratio: 1,3‐diphenylguanidine, amerchol L‐101, benzalkonium chloride, benzoyl peroxide, cocamidopropyl betaine, octyl gallate, phenyl mercuric acetate and propylene glycol), patches with SLS 0·5% and 0·25% aq. were applied. Reactions to the allergens and to SLS were analysed at the IVDK data centre. The association between an erythematous or positive reaction to a certain allergen and an irritant reaction to SLS was assessed with logistic regression analysis, at the same time controlling for the influence of age and sex. Results Of the 29 allergens of the standard series, 23 and 21 gave a higher percentage of nonspecific erythematous reactions in patients with an irritant reaction to 0·25% and 0·5% SLS, respectively, in comparison with SLS‐negative patients. All eight ‘problematic’ allergens gave an increased percentage of nonspecific erythematous reactions. Similarly, 22 and 21 allergens of the standard series gave a higher percentage of positive allergic reactions in patients with an irritant reaction to 0·25% and 0·5% SLS, respectively, and seven of the eight ‘problematic’ allergens gave a higher percentage of positive allergic rections (exception: octyl gallate). For most allergens, the markers of skin reaction (reaction index and positivity ratio) were worse in SLS‐positive patients. Differences were more pronounced when testing with SLS 0·25% than with SLS 0·5%. Conclusions Because there is a convincing association between skin irritability (evaluated by SLS test) and the degree of skin reaction to contact allergens, the SLS test may help in deciding whether a doubtful erythematous or weakly ‘positive’ skin reaction should be interpreted as allergic or irritant.     

Evaluation of skin susceptibility to irritancy by routine patch testing with sodium lauryl sulfate

Irritant patch testing with sodium lauryl sulfate (SLS) will become more and more a routine test determining skin susceptibility in men. Recently, it has been shown that for practical reasons, irritant SLS patch testing can take place on the back simultaneously with a routine allergic patch test to other contact allergens. However, SLS patch testing has mostly been performed on the forearm in studying experimental skin irritation so far. The aim of this study was to determine whether there is a relationship in skin response to aqueous SLS (0.125%; 0.25%; 0.5% and 1.0%) between the forearm and the back assessed by visual scoring and measurement of transepidermal water loss (TEWL). We found a pronounced reaction of the forearm compared to the back. TEWL values as well as visual scores correlated well with SLS concentration. There was also a high correlation in visual scoring between the forearm and the back. Based on test sensitivity and specificity we suggest a 48 hrs patch test for routine screening with 0.5% SLS on the forearm evaluated by TEWL measurement or visual scoring 24 hrs after patch removal. A mild erythema (scored as < or =1) is considered to be normal. If for practical reasons, the SLS patch is placed on the back simultaneously with the allergic patch test, 0.5% SLS may be sufficient, too. TEWL measurement so far provides a reliable method and will certainly be necessary for experimental studies on irritant skin reactions, particularly when different SLS concentrations are used. After a 48 hrs patch test with SLS 0.5% TEWL measurement should be performed at 72 hrs. A value of < or =31.6 g/m(2)hr seems to follow the normal distribution.     

FS01.7Prevalence of contact allergy in an adult Thai population

There is only very limited data on the prevalence of contact allergy, as judged by a positive diagnostic patch test, in unselected, non‐clinical populations. We carried out a 48 h patch test to 7 common allergens and to the petrolatum vehicle in a total of 2545 adult volunteers in Bangkok. The patch tests were read at 48 h approximately 1 h after patch removal. Positive results were as follows Ni 27.8%, fragrance mix 2.9%, Cr 2.6%, PPD 2.3%, colophony 2.1%, MI/MCI 1.2% and formaldehyde 0.7%. No reactions were found to petrolatum. The particularly high frequency of reactions to Ni was surprising.
However, the large female bias (approximately 75:1) strongly suggested that, despite the absence of a 96 h score, that irritancy did not play a significant part in these reactions. Reaction rates to the other 6 contact allergens appeared to confirm predictions made from the extrapolation of diagnostic patch testing or from previous published studies on smaller population groups. The rates of reaction to these allergens also are likely to reflect the extent of exposure in the Bangkok region. Nevertheless, it is interesting to note that over 2% of this adult population appear to be allergic to the cosmetic related allergens PPD and fragrance.     

European multicenter study of TRUE Test™, Panel 2

Panel 2 of the standardized, ready-to-apply patch test, the TRUE Test, has been evaluated on 808 patients with suspected contact dermatitis. The patients were tested with 11 different allergens and the negative control, and compared with corresponding allergens in pet. (or aq.) in Finn Chambers fixed with Scanpor. The TRUE Test, Panel 2 and the control were applied symmetrically on the upper back. Left/right application of the respective test varied at random. Most tests were removed after 48 h and evaluated after 72 or 96 h, according to generally accepted recommendations. There were positive test reactions to all 11 allergens tested in the patient group. The concordance of positive reactions (1+, 2+, 3+) was 63% between TRUE Test, Panel 2 and the control method; 17% of positive reactions occurred only with TRUE Test, Panel 2 and 20% only with the compared method. Approximately 75% of all positive test reactions were explained by the patients' present or past history. Irritant/questionable reactions occurred in the same frequency for the 2 methods. Such reactions were recorded in less than 1% of all patches applied. No late reactions were recorded.     

Active participation of eosinophils in patch test reactions to inhalant allergens in patients with atopic dermatitis

Intracutaneous testing and patch tests with house dust mite and grass pollen allergens were performed in patients with atopic dermatitis. Only patients with an immediate type skin reaction to house dust mite or grass pollen allergens showed a positive patch test reaction to these allergens 24-48 h after testing. Occasionally positive patch test reactions at 20 min, 2 h and 6 h were also observed. Patch test reactions were not found in normal controls or atopic patients without atopic dermatitis. Analysis of the cellular infiltrate demonstrated an influx of eosinophils into the dermis, starting from 2-6 h after patch testing. Immunostaining with antibodies against granular constituents of the eosinophils revealed that the infiltrating eosinophils were in an activated state and had lost part of their granular contents. At 24 h eosinophils also appeared in the epidermis. Electron microscopy showed that in the epidermis, some eosinophils were in close contact with Langerhans cells, suggesting a cell-cell interaction. Taken together, these results strongly suggest an active role for eosinophils in patch test reactions to inhalant allergens in atopic dermatitis patients.     

Patch testing in Iranian children with allergic contact dermatitis

Background

Allergic contact dermatitis is a common disorder in adults and children alike and appears to be on the increase. The purpose of this study was to determine the sensitization trends in Iranian children with contact dermatitis.

Methods

The result of 109 patch tests performed using the 24 allergens of the European Standard Series in patients below 18 years old from September 2007 to March 2009 were recorded and analyzed. The tests were evaluated at 48 and 72 h after performing.

Results

The study population consisted of 72 (66.1 %) females and 37 (33.9 %) males. Hands were the most commonly affected anatomic site. In the final evaluation of the tests on day three, 51 (46.8 %) individuals showed a positive reaction to at least one allergen. Females were significantly more likely to show a positive response to at least one allergen (p-value?=?0.031, odds ratio: 2.46). The most common allergens were nickel sulfate, cobalt, methylisothiazolinone, and colophony with 21 (19.3 %), 11 (10.1 %), 7 (6.4 %), and 6 (5.5 %) positive reactions, respectively. Contact allergy to nickel sulfate was more common in females than males (23.6 % vs. 10.8 %). There was no statistically significant relationship between personal or family history of atopy and a positive reaction to patch testing. The clinical and practical relevance were assessed for nickel and cobalt with a clinical current relevance in 11 (52.3 %) and 4 (36.4 %), respectively.

Conclusions

Nickel sulfate, cobalt, methylisothiazolinone, and colophony are the most common allergens responsible for induction of allergic contact dermatitis in Iranian children and adolescents. Females tended to show more positive reactions to allergens.

     

Murine auricular transepidermal water loss -- a novel approach for evaluating irritant skin reaction in mice

The standard method for evaluating contact allergy in mice is the ear swelling technique. However, in experimental irritant contact dermatitis, the epidermal barrier disruption, that represents a predominant effect of irritants, cannot be assayed by this METHOD: An appropriate method to evaluate barrier disruption is the measurement of transepidermal water loss (TEWL) but to date this has so far been possible only on the trunk of hairless or shaved mice. We therefore developed a new technique to measure the TEWL of mice ears (murine auricular TEWL: MATEWL). After patch testing with irritants and allergens, respectively, we found that the ear swelling method is most suitable for evaluating allergic skin reactions, whereas MATEWL is most appropriate for evaluating irritant skin reactions.     

Updating the British Society for Cutaneous Allergy Facial Series to ensure accurate diagnosis of allergic contact dermatitis

Allergic contact dermatitis (ACD) is a localised form of dermatitis or eczema which occurs 48‐72 hours after a substance which causes allergy (an allergen) has been in contact with the skin. It affects 20% of people. ACD to cosmetics is widely reported, with facial eczema being the main presenting complaint. ACD to cosmetics is diagnosed by patch testing to the British Society of Cutaneous Allergy (BSCA) facial series. Patch testing is a specialist test performed by a dermatologist which involves applying a series of allergens to the patient’s back, which remains in place for 48 hours until they are removed. The patient then returns, 72 hours after the initial application of the allergens, for the final readings to see if they have any positive allergic reactions. To ensure we are accurately diagnosing ACD, patch test series should be continually reviewed to identify relevant and emerging allergens and remove those that are outdated. The BSCA facial series currently recommends 26 allergens and was last modified in 2012. We set out to update the BSCA facial series. We assessed the results from 12 U.K. and Ireland patch test centres’, facial series from January 2016 to December 2017. We recorded the number of allergens tested in each centre and calculated the patch test rate for each allergen, using a 0.3% positive patch test rate as the threshold criterion for inclusion. A total of 4224 patients were patch tested to the BSCA facial series. The number of allergens included in individual centres facial series ranged from 24 to 66 with a total of 103 allergens tested across all centres. Twelve of the 26 allergens in the BSCA facial series had a positive patch test rate of less than 0.3% and 14 had a rate more than 0.3%. Twenty‐five allergens not recommended in the BSCA facial series had a positive patch test rate more than 0.3%. Despite a recommended facial series, there is wide variation in practice amongst patch test centres. Using our results, we have updated the BSCA facial series which now contains 24 allergens. Fifteen allergens remain, 11 allergens have been dropped and nine new allergens have been added. Linked Article:   Rolls et al. Br J Dermatol 2021; 184 :151–155 .     

Atopy patch test reaction to airborne allergens in the diagnosis of atopic dermatitis

The aim of the study was to evaluate the possible use of atopy patch test in the diagnosis of atopic dermatitis and to characterize an optimal standardized system for atopy patch test in terms of allergen concentrations and time of allergen exposure. The study included 36 patients with atopic dermatitis and IgE-mediated airborne allergy. Patients presented positive results of skin prick tests and serum antigen specific IgE against house dust mite allergens and/or selected grass pollen allergens. Control groups consisted either of patients with allergic rhinitis (control group 1) or healthy volunteers with no signs or symptoms of atopy (control group 2). Allergologic diagnostic workup consisted of skin prick test, serum antigen specific IgE and total IgE evaluation, atopy patch test with selected airborne allergens of different concentrations (0.1xSPT, 1xSPT and 10xSPT), time of allergen exposure (8, 24 and 48 h), and readings of the results (8, 24, 48 and 72 h). Positive results of atopy patch test with airborne allergens were obtained in 47.2% of atopic dermatitis patients and none of control subjects. Contact reaction itself and the intensity of reaction were demonstrated to correlate with allergen concentration and time of allergen exposure on atopy patch test. The dose and time response analysis showed the optimal concentration of allergens for atopy patch test to be 10xSPT, 500000 SBE/ml, and optimal evaluation time 24 and 48 h of allergen application. There was no correlation between atopy patch test results and mean serum concentrations of total or antigen specific IgE. Atopy patch test results did not correlate with localization of skin lesions, severity and extensiveness of skin inflammation. A significantly higher contact reactivity to airborne allergens was recorded in the group of atopic dermatitis patients with polyvalent allergy in comparison with atopic dermatitis patients allergic to only one aeroallergen. It is concluded that atopy patch test is the only provocation test currently available with clinical relevance for contact IgE-mediated sensitization in atopic dermatitis patients. Using petrolatum as a vehicle, allergen concentration of 500000 SBE/ml and evaluation time of 24 and 48 h of allergen application may lead to improved atopy patch test results.     

Value of the cutaneous basophil hypersensitivity (CBH) response for distinguishing weak contact sensitization from irritation reactions in the guinea pig

Numerous studies of the histology of allergic contact dermatitis reactions to potent allergens in guinea pigs and humans have indicated that there is significant tissue infiltration with basophilic leukocytes. In this study we determined whether this histologic finding could be of value in distinguishing weak sensitization reactions from primary irritation, thereby aiding in the predictive identification of weak or moderate contact allergens. Guinea pigs were sensitized by the Buehler test method. Skin reactions were graded 24, 48, and 72 h post-challenge with duplicate patch sites biopsied at the 24- or 72-h grading timepoints. The biopsies were fixed, embedded in glycol methacrylate, thin sectioned, and Giemsa stained. The number of basophils per 400 leukocytes were counted along the upper dermis just below the dermal/epidermal junction. Challenge patch sites from animals sensitized to a relatively low dose of the strong contact allergen, oxazolone, were compared with patch sites from animals challenged only with a strong irritant, sodium lauryl sulfate (SLS). Compared to normal skin (7.5 +/- 1.0 basophils/400 leukocytes +/- SEM) only the oxazolone patch sites showed significant basophil infiltration (36.8 +/- 6.5), despite the fact that the skin reactions to the low oxazolone challenge dose were relatively weak. SLS patch sites showed no basophil infiltration above normal skin levels (4.8 +/- 0.9). Subsequent blinded studies compared weak/moderate presumptive sensitization reactions (as defined by accepted visual skin grading criteria) to various chemicals (citronellal, vanillin, cinnamic aldehyde, and ethylenediamine) to primary irritation reactions to the same chemicals. In each case, low-challenge-dose sensitization sites on previously treated (induced) animals showed mean basophil infiltration (range, 11.9-69.2 basophils/400 leukocytes) significantly greater than higher-dose irritant reactions (range, 1.6-13.3). The range for normal skin was 0.2-10.2 and the range for strong patch reactions to higher concentrations of oxazolone was 59.8-209.3. These data strongly indicate that light-microscopic quantitation of the CBH response can be used to distinguish relatively weak to moderate contact sensitization reactions from primary irritation reactions to the same chemicals.     

The importance of checking for delayed reactions in pediatric patch testing

Abstract: Patch testing is often performed with the final reading being completed at 72 hours. Studies in adults have shown that performing an additional reading several days later increases the yield of relevant positive reactions. We report a study of this matter in children. We conducted a prospective patch test study of 38 affected children aged 6 to 17 (mean 11.6 years), with presumed allergic contact dermatitis between April and July 2009. The patients were required to return at 48 hours for patch test removal and assessment of early reactions, at 72 to 96 hours (3–4 days) for evaluation of delayed reactions, and again at 168 to 216 hours (7–9 days) for a final late delayed reading. We tallied the number of patients with “equivocal” (+/?), +, ++, and +++ reactions and noted these as potential positive reactions by reading date. Twenty‐five of the 38 children (66%) had a positive reaction at 48 hours; 32 children (84%) had a positive reaction at 72 hours (day 3); 19 children (50%) had a positive reaction at 168 to 216 hours (day 7–9). Of those 19, 16 (42%) had persistent reactions, while 5 children (13%) had new late delayed reactions. Among the new late delayed reactions, there were six allergens identified, four of which were considered of probable clinical relevance. When patch testing with Thin Layer Rapid‐Use Epicutaneous test panels, a delayed reading beyond 72 hours may be needed to identify the offending agent(s) responsible for allergic contact dermatitis in some children. Additional studies are needed to assess optimal readings schedules.     

The diagnostic value of atopy patch testing and prick testing in atopic dermatitis: facts and controversies

We conducted a systematic Medline search of the literature (1998-2008) on the criteria for performing the skin prick test and atopy patch testing (APT) to determine their utility in atopic dermatitis (AD). The skin prick, scratch, and skin patch tests are performed to identify which allergen is causing eczematous skin symptoms in patients with AD, or sneezing, nasal congestion, itchy eyes, wheezing, skin rash, and swelling. Many allergens in foods, drugs, and environmental substances (eg, ragweed and fungus), as well as contact allergens, can elicit eczematous skin reactions after epicutaneous application. Because no gold standard exists for aeroallergen provocation in AD, the APT is currently used to evaluate allergen without comparison with another accurate and reliable method. The APT is presumed to reflect delayed-phase clinical reactions. Even with delayed onset of symptoms (more than 2 hours after food ingestion), APT findings were not consistent among AD children. The APT could be used in children with gastrointestinal reactions to foods as well as AD. After standardization, the APT may provide further diagnostic information in addition to the skin prick test and serum immunoglobulin E values and may be able to evaluate the actual clinical relevance of immunoglobulin E-mediated sensitizations for eczematous lesions. The European APT model used with standardization of allergen concentration and vehicle may provide an important diagnostic tool to select patients for avoidance and for procedures of allergen-specific immunotherapy, but the clinical relevance of positive APT reactions awaits standardized provocation and avoidance testing.     

免疫磁性技术分离提纯酵母样真菌的研究

用包被有羊抗鼠ＩｇＧ的磁珠结合鼠抗白念单抗后，对白念珠菌，类星形念珠菌，类星形念珠菌，热带念珠菌，新生隐球菌，光滑念珠菌菌悬液及白念珠菌与新生隐球菌两菌混悬液进行了分离纯化研究。结果：免疫磁球和白念珠菌，类星形念珠菌结合尤为明显，与热带念珠菌少量结合而不和新生隐球菌，光滑念珠菌结合。     

Iontophoresis of nickel elicits a delayed cutaneous response in sensitized individuals that is similar to an allergic patch test reaction

Wearing of patch test chambers for 1-2 days is uncomfortable for patients. Allergen application by iontophoresis avoids this, but it is unknown so far whether iontophoresis itself interferes with the delayed immune response. We compared the effects occurring 48 h after iontophoresis with distilled water, 0.9% NaCl, and 0.01 M NiSO4 in normal volunteers and in nickel-sensitized patients (total n=36). Visual assessment was performed and transepidermal water loss (TEWL), stratum corneum hydration, cutaneous blood flow, and immunohistopathology were determined. After iontophoresis with nickel sulfate, only individuals sensitized to nickel reacted with a positive clinical response, increase in cutaneous blood flow, decline in epidermal CD-1a-positive cells, increase in epidermal proliferation (Ki-67-positive cells), pronounced infiltration of cells positive for CD4, CD11, or CLA, and cellular activation (expression of ICAM1, HLA-DR). Iontophoresis with distilled water or saline did not result in such reactions in volunteers with or without nickel sensitization, and the latter also tolerated nickel iontophoresis without significant skin reactions. We conclude that the delayed cutaneous response to nickel induced via iontophoresis is specific and similar to a positive patch test reaction. Iontophoresis may therefore be considered as an alternative to patch testing.     

Patch testing is a useful investigation in children with eczema

Background. Allergic contact dermatitis in children is less recognized than in adults. However, recently, allergic contact dermatitis has started to attract more interest as a cause of or contributor to eczema in children, and patch testing has been gaining in recognition as a useful diagnostic tool in this group. Objectives. The aim of this analysis was to investigate the results of patch testing of selected children with eczema of various types (mostly atopic dermatitis) attending the Sheffield Children's Hospital, and to assess potential allergens that might elicit allergic contact dermatitis. Patients and methods. We analysed retrospectively the patch test results in 110 children aged between 2 and 18 years, referred to a contact dermatitis clinic between April 2002 and December 2008. We looked at the percentages of relevant positive reactions in boys and girls, by age groups, and recorded the outcome of treatment following patch testing. Results. One or more positive allergic reactions of current or past relevance was found in 48/110 children (44%; 29 females and 19 males). There were 94 allergy‐positive patch test reactions in 110 patients: 81 had a reaction of current or past relevance, 12 had a reaction of unknown relevance, and 1 had reaction that was a cross‐reaction. The commonest allergens with present or past relevance were medicaments, plant allergens, house dust mite, nickel, Amerchol® L101 (a lanolin derivative), and 2‐bromo‐2‐nitropropane‐1,3‐diol. However, finding a positive allergen was not associated with a better clinical outcome. Conclusions. We have shown that patch testing can identify relevant allergens in 44% of children with eczema. The commonest relevant allergens were medicament allergens, plant allergens, house dust mite, nickel, Amerchol® L101, and 2‐bromo‐2‐nitropropane‐1,3‐diol. Patch testing can be performed in children as young as 2 years with the proper preparation.