Contents
43.1 Introduction . . . . 811
43.2 Prevalence and Incidence . . . . 811
43.2.1 Prevalence of Contact Allergy in an Unselected Population . . . . 811
43.2.2 Prevalence of Contact Allergy in a Selected Population . . . . 812
43.2.3 Prevalence in Relation to Genetic Factors . . 814 43.2.4 Prevalence Related to Sex . . . . 814
43.2.5 Prevalence Related to Age . . . . 814
43.2.6 Prevalence Related to Origin . . . . 815
43.2.7 Prevalence in Relation to the Sensitization Source . . . . 815
43.3 The Clinical Picture . . . . 815
43.4 Allergic Contact Dermatitis and Atopy . . . . 816
43.5 Patch Testing in Children . . . . 817
43.6 The Most Frequent Allergens in Children . . 817 43.6.1 Metals . . . . 817
43.6.1.1 Nickel . . . . 817
43.6.1.2 Cobalt . . . . 818
43.6.1.3 Potassium Dichromate . . . . 818
43.6.1.4 Mercury . . . . 818
43.6.1.5 Aluminum . . . . 818
43.6.1.6 Palladium . . . . 818
43.6.1.7 Iron . . . . 819
43.6.1.8 Copper . . . . 819
43.6.2 Pharmaceutical Products . . . . 819
43.6.3 Cosmetics . . . . 820
43.6.4 Tattoos . . . . 821
43.6.5 Toys . . . . 821
43.6.6 Rubber Items . . . . 821
43.6.7 Shoes and Clothes . . . . 822
43.6.8 Plastic Materials and Resins . . . . 823
43.6.9 Plants . . . . 823
43.6.9.1 Poison Ivy, Poison Oak, Poison Sumac . . . . 823
43.6.9.2 Toxicodendron succedaneum (Rhus Tree) . . 823 43.6.9.3 Urtica urens . . . 824
43.6.9.4 Asteraceae or Compositae . . . . 824
43.6.9.5 Lichens . . . . 824
43.6.9.6 Gingko Fruit . . . . 824
43.6.9.7 Dioscorea batatas Decaisne . . . 824
43.6.9.8 Protein Contact Dermatitis . . . . 824
43.6.9.9 Various Plant Materials . . . . 824
43.6.10 Occupational Allergens . . . . 824
43.1 Introduction Contact allergy has not been studied as extensively in children as in adults. Although there are many simi- larities between these two patient populations, the results obtained in adults cannot always be applied to children. A child is not simply a small version of an adult. 43.2 Prevalence and Incidence Allergic contact dermatitis in children has always been considered rare, and their eczematous condi- tions have mostly been attributed to endogenous fac- tors such as atopic or seborrheic dermatitis, some- times in association with irritancy induced by soap, clothing, and so on [1–3]. One of the reasons for this would be their reduced exposure to environmental allergens (professional, cosmetic, pharmaceutical) [3, 4]. Some authors also cite a lower reactivity and sen- sitization capacity for children’s skin [5, 6]. Until fairly recently, allergic contact dermatitis was not usually suspected in children, so little patch testing was performed [7]. Since the 1980s, however, this diagnosis has been considered more frequently [8]. Photoallergic contact dermatitis does seem to be rare [1, 7], although it may too be under-diagnosed. 43.2.1 Prevalence of Contact Allergy in an Unselected Population Data on the prevalence of contact allergy in healthy children are scarce: in a population of 314 healthy Chapter 43
Contact Allergy in Children
A. Goossens, M. Morren43
43.7 Proposal for a Shortened Standard Series for Children . . . . 82543.8 Conclusions . . . . 825
Suggested Reading . . . . 826
References . . . . 826
children younger than 18 years old, Weston and co- workers [9] found positive patch test results in 20%;
Barros and coworkers [10] reported a 13% prevalence in 562 children aged between 5 and 14; while Dotte- rud and Falk [11] observed that 23% of 424 healthy children from 7 to 12 years old had a contact allergy.
More recently, Bruckner and coworkers [12] found that 24.5% of 85 children between 6 months and 5 - years of age, attending well-child visits and tested with a TRUE Test panel, presented one (16 infants) or two (4 infants) positive tests. Nickel and thimerosal were the most frequent allergens identified. However, Johnke and coworkers [13] warn for false-positive tests, especially with nickel sulfate in such young children: they found many (111/543 infants) weak transient reactions with the highest (200 µg/cm2) nickel concentration tested, of which only 8.6% could be reproduced. Hence, single positive nickel patch tests in small children should be assessed with cau- tion! In a Danish study on adolescents between 12 and 16 years old, a prevalence of 15.2% was found, the
relevance of which was estimated to be 50%, for the present or the past (7.2%). Girls reacted more fre- quently [14].
43.2.2 Prevalence of Contact Allergy in a Selected Population
Several studies have been performed in children sus- pected of contact allergy or suffering from atopic or juvenile plantar dermatitis, orofacial granulomatosis, dyshidrosis, psoriasis, photosensitivity, urticaria, or other dermatoses. The studies ([15–37], see Table 1) differ in the numbers and ages of the patients in- volved, the clinical symptoms, as well as the relevan- cy and the prevalence of the positive reactions ob- served. In a study by Pambor and co-workers in 1991 [38], only 3.6% of the children tested showed clinical- ly relevant positive patch tests, whereas Pevny and co-workers observed relevancy rates of up to 71%
[16], with the majority around 40%.
43
Table 1.Incidence of allergic contact dermatitis in selected populations
Author, Number Age Categories % Relevancy Most frequent allergens (% of
Reference (%) children with positive test)
Veien et al [15] 168 <14 years Suspicion of ACD 46 80 Nickel > dichromate > rubber Pevny et al [16] 147 3–16 years Suspicion of ACD 71 93 Nickel > cobalt > para-dyes >
dichromate
Romaguera 1023 <14 years ACD and others 31 69.5 Nickel/cobalt > pharmaceutical
et al [17] (45% atopics) ingredients > cosmetics > shoes
> clothes > professional Rademaker and 129 <12 years Atopic eczema, eczema, 48 92 Metals > perfume > rubber
Forsyth [18] atypical JPD, contact
dermatitis, orofacial granulomatosis, other
Kuiters et al [19] 67 <16 years Dermatitis 28 84 Nickel > balsam of Peru > fra- grance mix > colophony > car- ba mix
Balato et al [20] 585 <14 years Eczema 14 ? Nickel > cobalt > ethylenedia- mine > dichromate > mercury ammonium chloride > mercap- tobenzothiazole > neomycin >
mercapto mix
Pambor et al [21] 366 2–14 years Atopic dermatitis 25 5 Nickel > chloramphenicol >
(n=214) parabens > turpentine
Other dermatosis 18 7
(n=142)
Ayala et al [22] 323 <14 years Atopic dermatitis 35.2 61.7 Metals > pharmaceutical Contact dermatitis ingredients > preservatives >
Dyshidrotic eczema fragrance > shoes
Foot, diaper or perioral eczema (palmar/plantar psoriasis)
Gonçalo 329 <14 years ACD 51.7 65.3 Nickel, thimerosal, cobalt,
et al [23] mercury ammonium chloride,
fragrance mix, dichromate
Table 1.Continued
Author, Number Age Categories % Relevancy Most frequent allergens (% of
Reference (%) children with positive test)
Sevilla et al [24] 272 2–14 years ACD 37.1 54.4 Nickel, rubber, mercury
chloride, cobalt, thimerosal, benzoyl peroxide, fragrance mix
Motolese 53 <3 years Dermatitis 50 62.5 Thimerosal, nickel, ammoniated
et al [25] mercury
Stables et al. [26] 92 3–14 years Atopic dermatitis 32.6 87 Nickel, fragrance mix, balsam Localized dermatitis of Peru, thimerosal, neomycin,
JPD cobalt, lanolin, dichromate,
Orofacial granulomatosis mercapto mix
Reactions to vaccines Atypical psoriasis
Rudzki et al [27] 626 3–16 years ? 42.7 ? Nickel, dichromate, cobalt, mer-
cury chloride, fragrance mix, para-phenylenediamine, neo- mycin, balsam of Peru
Wilkowska 100 5–15 years Atopic dermatitis 49 ? Dichromate, cobalt, neomycin
et al [28] Eczema
Nonallergic dermatoses
Katsarou 232 <16 years ACD ? 43.5 ? Nickel, cobalt, fragrance mix,
et al [29] dichromate,para-phenylene-
diamine,para-tertiary-butyl- phenol-formaldehyde resin, mercapto mix, mercury ammo- nium chloride, balsam of Peru
Wantke et al [30] 234 <15 years ACD ? Ethylmercuric chloride,
72 0–7 years 44.65a thimerosal and nickel (girls)
162 7–14 years 40.51a
Brasch et al [31] 416 6–15 years ACD 41 ? Nickel, thimerosal, benzoyl
peroxide, fragrance mix, cobalt, amalgam, mercury ammonium chloride, phenyl- mercury acetate, Amerchol L-101, cobalt chloride, dichro- mate, colophony
Shah et al [32] 83 6–16 years Atopic dermatitis 49 ? Nickel, fragrance mix, cobalt,
Hand/feet dermatitis neomycin,para-phenylene-
(Peri)oral dermatitis diamine, colophony,para-
Reactions to local tertiary-butylphenol-
anesthetics formaldehyde resin
Dermatoses with unusual localizations Perianal dermatitis Urticaria
Photoreactions
Manzini 670 6 months Dermatitis 42 ? Thimerosal, nickel,
et al [33] to 12 years methyl(chloro)isothiazolinone,
fragrance mix, neomycin, wool alcohols, ammoniated mercury
Romaguera 141 <15 years ACD 50 80 Nickel, cobalt, mercurials,
et al [34] fragrance, rubber
Giordani-Labadie 137 <16 years Atopic dermatitis 43 ? Metals (mainly nickel),
et al [35] fragrance, balsam of Peru,
lanolin, neomycin
Roul et al [36] 337 <16 years ACD 66 ? Nickel, fragrance, rubber
Duarte et al [37] 102 10–19 years ACD 56 100 Nickel, tosylamide/
formaldehyde resin
aBoys and girls respectively
Other factors that render comparison of those studies difficult [26] include the different test popu- lations involved (for example the presence or not of atopy, differences in origin and habits), the variabil- ity of the test conditions (materials, allergens, con- centrations, vehicles, reading times), and the inter- pretation of the test results (allergic or irritant).
The question arises as to whether contact allergy in children has become more frequent in recent years. According to Björksten [39], its prevalence in 18-year-old Swedish males increased from 0.9% in 1978 to 1.5% in 1993.
쐽 Contact allergy in children is more frequent than previously suspected, the prevalence in an unselected population being about 20%.
43.2.3 Prevalence in Relation to Genetic Factors
According to Walton and coworkers [40], occupa- tional and environmental factors are essential but the hereditary background can also be important, as could be demonstrated, for example, by the higher prevalence of HLA-B35 and BW22 antigens and their correlation with an increased risk of nickel sensitiza- tion in a female population. The importance of ge- netic factors has also been studied in children [41–43]: these authors conclude that there is a specif- ic genetic selection at the level of the peripheral T- lymphocyte system.
43.2.4 Prevalence Related to Sex
While some authors [9, 10, 26] detected similar prev- alence in both boys and girls, others [11, 30] reported a higher prevalence in girls. This is especially the case for nickel [15, 40, 44] and after the age of 12 [18, 27, 29].
Hormonal factors may be a contributory factor here [23, 31]. Kwangsukstith and Maibach [45] have formu- lated several arguments for the existence of sex-relat- ed differences in the prevalence of allergic contact dermatitis: varying test results obtained depending upon the menstrual cycle; increased sensitization li- ability in females, in general, and enhanced reactivity to dinitrochlorobenzene (DNCB) in females taking contraceptives; allergic contact dermatitis due to
transdermal clonidine being more frequently ob- served in women than in men; and finally, a greater susceptibility of feminine skin to irritation and hence to sensitization.
43.2.5 Prevalence Related to Age
Unlike some authors [10, 26, 36, 44], most report an increasing prevalence of allergic contact dermatitis with age, and attribute it to the increasing exposure to environmental allergens [8, 20, 24, 27, 28, 46]. This also applies to the development of multiple sensitiv- ities [23]. A reduced sensitization potential in young- er children has also been suggested [5, 6]. This has been experimentally demonstrated by Uhr and co- workers [47], who showed that sensitization to dini- trofluorobenzene does occur among premature in- fants but less frequently than among infants carried to term, and in both of these groups less frequently than in children aged 2–12 months. Epstein [48] ob- tained sensitization to pentadecylcatechol in 44% of children below 1 year of age, in about 58% between 1 and 3 years old, and in 87% of children between 4 and 8 years old. In contrast to this, Moltolese and cowork- ers [25] found a contact allergy in 32/53 infants (3 months to 2 years) with dermatitis. At least 20 out of the 32 were considered relevant.
Fisher reported several cases of allergic contact dermatitis in neonates and infants [49–52]: epoxy resin in a vinyl identification band in a 1-week-old neonate, three cases of ethylenediamine contact al- lergy (induced by Mycolog) in children aged 6 weeks to 1 year, one case of nickel allergy due to earrings in a 4-week-old girl, neomycin as a cause of an allergic contact dermatitis on the penis of a 5-week-old boy who was circumcised, balsam of Peru in an ointment to treat diaper rash in an 8-week-old girl (who had received this treatment for only 1 week), and finally nickel in underwear causing a row of contact derma- titis lesions on the back of a 7-month-old boy. Seide- nari [53] also described three remarkable contact al- lergy cases (two of them connubial) in babies: nickel present in the bars of a crib caused dyshidrosis of the hands and feet in a 12-month-old atopic boy; nickel in his mother’s jewelry (she wore rings on all her fin- gers) exacerbated the atopic eczema of a 6-month- old boy; and para-phenylenediamine in her mother’s dyed hair caused hand dermatitis in a 12-month-old girl. Aihara and Ikezawa [54] have reported a neonate who was allergic to a mydriatic agent used for fun- doscopy (the responsible allergen was not detected).
Moreover, several cases of contact allergy in in- fants have been reported due to the rubber anti-leak- ing system in their diapers [55–57].
43
Core Message
Recently, we diagnosed a contact allergy to the electrodes used to monitor an infant for sudden death. An allergy to para-tertiary-butylphenol-for- maldehyde (PTBPF) resin was found, but we were not able to confirm the presence of this allergen in the electrode.
43.2.6 Prevalence Related to Origin
The exposure of children to certain contact allergens varies throughout the world [8]. For example, in con- trast to Europe, poison ivy (and other members of the Rhus family) is particularly apt at inducing sensi- tization in certain parts of North and South America [1, 8]. In Scandinavian countries, plant dermatitis in children is rare except for reactions to Heracleum spp. [3]. Exposure and subsequent sensitivity to neo- mycin also seems to vary geographically; for exam- ple, there is a high prevalence in Portugal [10], Italy [22], and certain areas in the USA such as Denver [9], as opposed to Philadelphia [58]. In contrast to Scan- dinavian countries [3], shoe dermatitis seems to be particularly common in the USA [59], mainly due to rubber [58]. In developing countries occupational al- lergy is more common in older children than in Western countries [37].
Regional variations in the type of clothing and liv- ing conditions clearly influence the allergen spec- trum [15].
43.2.7 Prevalence in Relation to the Sensitization Source
Objects or materials common to the child’s environ- ment may give rise to some unusual allergen sources.
Diapers [55–57], and, for example, wirh regard to al- lergic cheilitis and perioral dermatitis, sucked-on objects are not at all rare causes (also due to rubber allergens), particularly in the younger age group [60]. This also applies to mercurials [31, 59] present in vaccines and topical pharmaceuticals used to treat abrasions and infections of the skin. However, nickel [22, 31], cosmetic ingredients [8], and occupational allergens [5, 16, 37] are causes of allergy more in old- er children. The prevalence of the allergens found mainly depends on the exposure, which itself varies with the age of the population [30].
43.3 The Clinical Picture
The clinical characteristics of allergic contact derma- titis are, in general, the same in children as in adults.
It is of the utmost importance to take a detailed his- tory, in order to specify the environment of the child and of those taking care of it, and to examine thoroughly the topography of the lesions. The local- ization is often an indication of the allergen or aller- gens involved [8]. Based on data published in the lit- erature, we compiled a list of allergens in relation to specific body sites (see Table 2).
Sometimes the clinical picture is unusual:
쐽 A hypertrophic verrucous cheilitis due to the topical application of thimerosal used to treat fissures [61]
쐽 A bullous dermatitis induced by a neomycin- containing finger bandage; patch tests were positive to neomycin, colophony, and thiuram mix [16]
Table 2.Correlation between the localization of the lesions and the nature of the allergens
Face: Ingredients of topical pharmaceuti- cal products (e.g., benzoyl peroxide), cosmetics [e.g., methyl(chloro)iso- thiazolinone], and perfume compo- nents; plants
Periorbital area: Ophthalmic preparations; nickel, cobalt
Perioral area: Stuck-on objects (rubber additives);
nickel, cobalt, and palladium; flavor- ing agents (cinnamic aldehyde) Ears: Nickel and cobalt, eardrops
Neck: Nickel
Trunk: Clothing dyes, rubber additives, nickel (periumbilically), PTBP-resin (electrode), PPD and essential oils in temporary tattoos
Arms: Cosmetics (e.g., sunscreens), alumi- num (vaccines), plants, PPD and essential oils (temporary tattoos) Wrists: Nickel and cobalt, dichromate
(leather watch-strap)
Hands and fingers: Preservatives (cosmetics, play gels, Plasticine), nickel and cobalt, plants, rubber and resin components Buttocks and thighs: Aluminum (vaccines), plastic
(toilet seat)
Diaper area: Topical pharmaceutical (e.g., ethy- lenediamine, neomycin) and cos- metic products, rubber (or glue) in anti-leaking system from diapers Legs: Plants, orthopedic appliances
(resins, such as PTBPF and epoxy) Feet: Shoe allergens (rubber additives,
glues) (PTBP), dichromate, plants, topical pharmaceutical products
쐽 A “baboon syndrome” [62, 63] from mercury, due to the intake of erythromycin to treat an infection of the throat [64]
쐽 An EEM-like eruption on the thighs spreading to the trunk after an initial contact eczema- tous reaction induced by a plant extract con- taining St John’s wort [65], to a temporary henna tattoo [66], to disperse dyes in a 2 year old boy [67], to tea tree oil [68] as well as to mephenesin (own observation)
쐽 A lichenoid contact dermatitis on the feet, hands, and buttocks lasting 6 years, due to topical aminoglycosides in which lichenoid positive patch tests were also obtained [69] (a papular pattern of allergic contact dermatitis does not seem to be rare, such as occurs with nickel [70]); this lichenoid pattern of reaction is also frequently seen in reactions to p-phen- ylene-diamine (PPD) in temporary tattoos [71]. Healing may be with depigmentation [72]
쐽 Itching nodules and granulomas that may per- sist for months or even years at the injection site of vaccines due to a delayed reaction to aluminum in vaccines [73]
쐽 A generalized nummular dermatitis in both a boy and a girl induced by application of an ethylenediamine-containing preparation to the groins and the feet, respectively [74]; a positive reaction to thimerosal was found in five atopic children (7–28 months old) with nummular eczema on the trunk, limbs and face [75]
쐽 A generalized eczema occurred twice in an 18- month-old boy caused by sensitivity to phe- noxyethanol used as a preservative in a DTP vaccine [76]; the third booster vaccine con- taining thimerosal as the preservative did not produce a reaction
쐽 A systemic contact dermatitis in a 14-year-old boy caused by an orthodontic appliance that contained nickel [77]
쐽 Certain contactants are characteristic of children (Table 2), and may be responsible for unusual clinical presentations.
43.4 Allergic Contact Dermatitis and Atopy The association between atopy and contact allergy in children is a controversial subject [78].The conclu- sions drawn differ largely according to the allergens investigated and whether the prevalence of contact allergy in atopic children or the prevalence of atopy in children suffering from allergic contact dermatitis children is being investigated [79].
Several authors were unable to detect differences between atopic and nonatopic subjects in this regard [22, 80, 81], but others have. Some authors were able to find a higher prevalence in atopic than in nonatop- ic children [11, 28, 82] and this was sometimes attrib- uted to the greater permeability of irritated skin [11].
Others report the opposite [26, 29, 31, 47].
Nickel reactions are more often seen in atopics [70, 81, 83], and then mainly in girls [84], which re- flects the greater importance of sex and ear piercing than atopy as such. The latter authors (in agreement with, for example, Pambor and coworkers [80]), stress the irritant properties of metals and particu- larly nickel on atopic skin, and, indeed, papulopustu- lar patch test reactions are a frequent finding [79].
Dotterud and Falk [84] doubt that metal sensitivity is associated with atopy. First, there is the reduced cel- lular immunity of atopics: positive reactions are found more often in atopic children with moderate dermatitis than in those with severe atopic eczema [85, 86]; second, there is the greater permeability of diseased skin, particularly on the hands, which facil- itates the penetration of allergens [85, 87].
Besides nickel, Oranje and co-workers [88] also found cobalt and balsam of Peru (Myroxylon perei- rae) to be important allergens in an atopic child pop- ulation; furthermore, they observed few reactions on patch testing with food.
Contact allergy to ingredients of topical medica- tions are also common in atopic dermatitis patients [35, 78].
As with nonatopics, the prevalence of contact al- lergy was found to increase with age [86, 87].
쐽 Positive reactions in atopics must be interpreted carefully, as atopic skin is readily irritated; this is especially the case for metals.
43
Core Message Core Message
43.5 Patch Testing in Children
Patch testing is indicated not only when contact al- lergy is suspected, but also in cases of persistent ecze- ma [20] on specific localizations, such as on the hands and the feet and around the mouth [32] and al- so in the umbilical region, particularly in atopics [79]. The latter group should certainly be tested when multiple exacerbations occur, even when they are treated, or when the dermatitis is asymmetrical [32].
Most authors agree that patch testing in children is safe [9, 18, 61, 89], the only problems being mainly technical due to the small patch test surface [18], hy- permobility (which may result in loss of patch test materials), particularly in younger children [32], and the reluctance of some parents to allow patch testing [4, 32]. Mallory [90] gives the following instructions when testing children:
쐽 Test in different sessions if the test area is very small
쐽 Should the patches come off, ask the parents to report it and instruct them not to reapply them
쐽 It may be necessary to use a stronger adhesive than usual, though this could be irritating [9]
쐽 The application has to be performed as quick- ly as possible while the child is distracted
쐽 Make a diagram of the tested allergens (this applies for adults, too)
쐽 Inform the parents about the test procedure and the measures that may be taken to opti- mize the patch test conditions
The patch test concentrations have been discussed in detail in the literature. Some authors have recom- mended lower concentrations [3, 80, 91, 92], particu- larly with regard to specific allergens such as nickel and formaldehyde [6, 83], mercurials [61], potassium dichromate, MBT, and thiuram mix [52]. Irritancy problems have been reported with patch testing, es- pecially in the younger age group [6, 9, 11, 21], while others use the same test concentrations as in adults [5, 15, 16, 26, 53, 81, 93]. Wahlberg and Goossens [94]
critically reviewed studies on the prevalence of con- tact allergy, and found that very high prevalences are found in “healthy” children as compared with those found in adults. They suspect that a lot of those reac- tions might be irritant and therefore conclude that all patch test concentrations used in adults are not nec- essarily suitable for use in children, as was already suggested for metals by Roul and coworkers [36]. In dubious cases one might have to retest with a lower test concentration [79]. Moreover, as with patch test-
ing in general, false-positive as well as false-negative reactions may occur [1, 49]. It is therefore important that the relevance of the tests are further investigat- ed, if necessary, with a serial dilution test, repeated open application test (ROAT) or a usage test [95]. For marginal irritants such as dichromate, fragrance mix, formaldehyde, mercury compounds and carba mix in particular [94], repeated patch testing with standardized tests (such as TRUE Test) should be performed in order to demonstrate reproducibility and, if necessary, the concentration should be adapt- ed. Johnke and coworkers [13] have already demon- strated that in infants 200µg/cm2nickel sulfate pro- duces many transient reactions (111/543), whereas re- producible tests were obtained only in 8.6% of the cases. They therefore favor a lower patch concentra- tion for nickel in children.
쐽 Patch testing in children is safe, but false- positive reactions are possible. Particularly for children under the age of five, patch testing should only be performed if there is high suspicion by history and clinical picture.
43.6 The Most Frequent Allergens in Children
43.6.1 Metals 43.6.1.1 Nickel
Nickel is the most common allergen both in children and adults in Europe, as it is in many other parts of the world. In the general population, about 10% of fe- males react to it, the prevalence being influenced by the increasing popularity of ear and other piercings [84]. Indeed, ear piercing along with atopy – the latter even in children between 4 and 17 months old [70, 96]
– have been regarded as major risk factors for the de- velopment of nickel sensitization, especially in girls [84, 97]. Boys may also be affected though [98]. Ra- demaker and Forsyth [18] could not determine sig- nificant differences between boys and girls below the age of 12. Subumbilical and periumbilical, mostly papular reactions are also common and are frequent- ly accompanied by an id-like spread [96, 99, 100].
Veien [101] attributes the high prevalence of nick- el allergy in young females to the common habit of
Core Message
wearing cheap jewelry, to reduced suppressor activ- ity correlated with their higher estrogen levels, and to higher skin permeability to nickel. Permeability could be increased by decreased iron levels associat- ed with menarche, as iron is a competitive inhibitor in the skin and on the surface of Langerhans cells.
Nickel sensitization sources in children are nu- merous: jewelry, even when worn by the mother [53]
and particularly earrings [49, 51] (stainless steel, even though silver- or gold-plated is not always “safe” in this regard [102]), metal buttons and snaps in under- wear, identification bracelets, safety pins, zippers, jeans and belt buckles [90, 96, 99, 100], metal accesso- ries on shoes, coins, metal toys, magnets, medallions, keys, door handles, and so on [51, 83]. Even bed rails have caused nickel contact allergy [53, 103]. Due to re- strictions on the concentration of nickel allowed in jewelry, advised by the authorities in Europe in the beginning of the 1990s, a decline in the prevalence of nickel allergy has been registered in Denmark [104]
and Germany [105]. In the USA, Byer et al [100] could only detect nickel in 10% of 74 pairs of jeans buckles, whereas the dimethylglyoxime test was positive in 25 of the 47 belts, indicating that this nickel source is more important for sensitization induction.
Orthodontic appliances may occasionally be at the origin of a nickel allergy, causing cheilitis, perioral eczema [77, 106, 107] and also stomatitis, sometimes associated with systemically induced dermatitis on the eyelids, fingers, ears, periorbital area [107], or more generalized reactions [77], even a severe deteri- oration of atopic dermatitis [108]. Van Hoogstraten et al [98] were able to show that wearing a dental ap- paratus before nickel skin contact has occurred may actually induce tolerance to this metal.
A low nickel diet might be useful in resistant nick- el allergy cases [15].
43.6.1.2 Cobalt
Cobalt allergies are often found in association with nickel allergies in both adults and children [31]. Not only metallic objects but also certain plastic materi- als may release cobalt or cobalt salts and induce con- tact sensitivity. For example, Grimm [109] described the case of an 11-year-old boy who had suffered for 4 - years from eczematous lesions at the site of his spec- tacle frames, on his wrist, and around his mouth. The dermatitis was attributed to cobalt present in the me- tallic part of his wristwatch, in the polyester resin- type plastics of the spectacle frames, and the ball- point pen which he habitually chewed on.
43.6.1.3 Potassium Dichromate
Leather seems to be the most important cause of chromium allergy; the examples published concern shoes (see below), a body splint [110], and a prayer strap in a 13-year-old Jewish boy [61]. Concomitant reactions to nickel have been observed [31].
43.6.1.4 Mercury
Contact allergy to mercurials is very common in chil- dren, particularly in countries where they are still widely used as antiseptics (for example mercuroch- rome), such as Spain [97, 111] and Italy [112]. Other sensitization sources for mercurials are other topi- cally applied medicaments, such as eye-drops, depig- menting creams [111], pediculosis preparations [113], vaccines [114], as well as broken thermometers [63], amalgam fillings, contact lens solutions, and pesti- cides. Levy and coworkers [59] warn against the use of mercurials in medications because of their poten- tial systemic toxicity, which may cause kidney dam- age, particularly when large skin surfaces are treated.
43.6.1.5 Aluminum
For aluminum, vaccines and occasionally also hypo- sensitization therapy in pollen allergy are reported as being the most important sensitization sources [73, 115–118]. Clinically, the reactions often present as long-lasting, pruritic, excoriated, subcutaneous nod- ules, occasionally accompanied by hypertrichosis [73, 119]. In many cases, the contact eczema is re- vealed by positive reactions to Finn chambers used in patch testing or to deodorants [115], eardrops [118], or even toothpaste [116] containing aluminum salts.
Flare-ups of previous injection sites may be ex- plained by the persistence of this metal in the skin [115]. The aluminum sensitivity is probably lost with time as this sensitivity is extremely rare in adults [120].
43.6.1.6 Palladium
This metal, shown to be an allergen in animals, is mainly present in orthodontic appliances and jewel- ry [121]. As with adults, most palladium-allergic chil- dren also react to nickel [31, 122], for which cross-sen- sitization seems to be the most plausible explanation.
43
43.6.1.7 Iron
There seems to be only one case report of iron con- tact allergy, which was caused by an orthopedic pros- thesis in a 7-year-old boy [123], so this metal seems to be an extremely rare allergen.
43.6.1.8 Copper
According to a Viennese report, copper, present in dental amalgam, caused problems in children [44].
43.6.2 Pharmaceutical Products
Many topical pharmaceutical ingredients have been described as allergens in children and should cer- tainly not be overlooked [124]. They include antibio- tics, mainly neomycin [16, 49], which is often used in the treatment of otitis [58]. Leyden and Kligman [58], in contrast to Weston and coworkers [9], suggest that neomycin allergy is less frequently seen in children than in adults. Cross-reactivity with other aminogly- cosides does occur [69]; antivirals such as tromanta- dine (own observations) and Zovirax, of which the responsible allergen could not be identified [125];
antihistamines such as dexchlorpheniramine ma- leate [126]; nonsteroidal anti-inflammatory agents such as fepradinol [127]; local anesthetics, particular- ly benzocaine [16], which often cross-reacts with oth- er ester-type anesthetics [90] and also with perma- nent hair dyes and textile dyes, which may later cause problems due to their chemical relationship [49].
Even corticosteroid preparations may cause contact allergy in children [128], and not infrequently in atopics [129]. Tixocortol pivalate and budesonide may be used as markers in the standard series, but all topical preparations used by the child should be test- ed as well. Contact allergy to the new class of topical immunomodulatory drugs, especially for tacrolimus, has been reported recently. A provocation test was positive after 1 week for lesions in the face but only after 7 weeks when applied to the antecubital region.
Patch tests were only positive after 5 days with tacrol- imus 5% and 2.5% in ethanol, but not with Protopic ointment as is, nor with lower concentrations of ta- crolimus. The authors suggest that the low percut- aneous absorption through intact extrafacial skin is the reason for this delay in positive results and the need for high concentrations [130].
Other agents which have been reported include quinine present in a balsam used in the treatment of respiratory infections (the adult formulation was used and not the one for children which did not con-
tain quinine [131]). Plant extracts may also be respon- sible for allergic reactions [65].
Certain topical medicaments are specifically used in older children, namely those used to treat acne such as benzoyl peroxide [1, 16].
An allergic dermatitis from the parenteral admin- istration of vitamin K has been reported by Pigatto and coworkers [132].
Not only active principles but also other ingre- dients may be responsible for allergic reactions in children: emulsifiers and vehicle components, such as wool wax alcohols and derivatives, propylenegly- col and cetostearyl alcohol, as well as a specific ingre- dient of eardrops – triethanolamine oleyl polypep- tide – are typical examples of this [133]. Sometimes, rarer allergens are involved such as laureth-4 [134], ethyl sebacate [128] and Tween 80 [135].
Ethylenediamine, used in Mycolog cream, has been widely used to treat various skin conditions, in- cluding diaper dermatitis [50, 74], and may cross- react with some antihistamines and aminophylline to induce severe systemic reactions [50]. This chemi- cal is also used in ophthalmic solutions, insecticides, fungicides, epoxy hardeners, and rubber stabilizers [90].
Preservatives are not at all rare causes of allergic reactions in children [136]. Goulden and Goodfield [137] reported the case of a 12-year-old boy who even reacted to a methylprednisolone injection due to his sensitivity to the preservative myristyl picolinium chloride.
Thimerosal has attracted much attention in the lit- erature, since it is frequently observed as an allergen in young children [138–140], and its inclusion in the standard series has been discussed [141, 142]. It is used as an antiseptic, disinfectant, and preservative agent for contact lens solutions, eyedrops, and vac- cines, the last being regarded as the main sensitiza- tion source through contamination of the tip of the needle [138, 139, 143, 144]. According to Möller [141]
and Aberer [144, 145], the many positive patch test re- actions found are in most cases not relevant to the patient’s skin condition.
A positive reaction to thimerosal should be taken into account with hyposensitization solutions, eye- drops, eye cosmetics, or contact-lens solutions [144], but does not seem to preclude future vaccinations, provided that they are administered intramuscularly.
Furthermore, as this molecule contains two allergen- ic parts – mercury and thiosalicylic acid – one must consider cross-reactions with other mercurials and with the photoproduct of piroxicam, which is chemi- cally related to the thiosalicylic acid part [114, 138, 146]. Efforts are now being made to omit thimerosal from commonly used vaccines [68].
Phenoxyethanol contact allergy has also been de- scribed in relation to a DTP vaccine [76].
Last but not least, adhesive tape can also be a cause of allergy due to colophony and thiuram derivatives [16]. Children may also be exposed to colophony in preparations to treat verrucae [120].
43.6.3 Cosmetics
The market for cosmetic products specially formu- lated for children is expanding and habits common for adults such as going to “beauty farms” are being adapted for this young age group. Consequently, one can expect cosmetics to become more important causes of contact allergy and they may become the most frequent cause of contact allergy in children [147]. At least one cosmetic or cosmetic ingredient gave a positive reaction in 30% of the children inves- tigated.
Almost every ingredient may be responsible for cosmetic dermatitis. Conti [136] reviewed preserva- tives and found that 44% of the children reacting to chemicals such as formaldehyde and its releasers, parabens, methyl(chloro)isothiazolinone, Euxyl K400 (methyldibromoglutaronitrile and phenoxyethanol), and the antioxidant butylhydroxyanisole (BHA), were atopic (Fig. 1).
The use of cosmetic products in babies and small children, and particularly those containing balsam of Peru (Myroxylon pereirae), has been described as be- ing the cause of a subsequent perfume allergy. Fisher [49, 50] has reported two such cases: one of a 4- month-old baby and another of an 11-year-old girl, both of whom became sensitized by the application of a balsam ointment in the diaper area. One later de- veloped contact eczema from the mother’s perfume and the other from a deodorant.
Fisher [60] further stated that children often be- come allergic to cosmetics used by the mother (or the
43
Fig. 1.
Allergic contact dermatitis from a play gel containing parabens
person taking care of them). In a 7-year-old girl with allergy to cinnamic aldehyde (cinnamal), cheilitis and perioral dermatitis were caused by the mother’s lipstick that was left after she kissed her. The local- izations often involved seem to be the forehead and the cheeks, with perfume, lipstick, hairspray, or nail lacquer as the responsible agents. A PPD allergy in- duced by the mother’s dyed hair was observed in a 12- month-old girl [53].
However, children often use cosmetic products themselves, even though this may not always be re- vealed immediately! An example of “ectopic” derma- titis, localized unilaterally on the face and neck, due to surreptitious use of the mother’s nail lacquer illus- trates this [61].
Although guidelines for the maximum concentra- tion of preservatives and fragrances in cosmetics have been provided [68], it has been demonstrated that cosmetic toys may contain much higher concen- trations of fragrance [148]. No extra safety require- ments for those products intended for children are required [120].
Contact allergy to the sunscreen agents 4-methyl- benzylidene camphor, isopropyl dibenzoylmethane, and 2-ethylhexyl methoxycinnamate has been de- scribed in an 18-month-old boy [149]. Shah and co- workers [32] reported two sunscreen agents as being the cause of photoallergic contact dermatitis. But in- gredients other than the sunscreen may also be re- sponsible, such as triethanolamine used as an emul- sifier [150], or recently, polymers added to make for- mulations more water resistant, such as polyvinyl- pyrrolidone-1-triacontene copolymer [151].
43.6.4 Tattoos
The practice of temporary henna tattooing has gained popularity in Western youngsters, especially when on holiday. Whereas contact allergy to henna itself seems to be rare, in tourist areas additives are added to make the process proceed more rapidly and to obtain a darker pigment. PPD, coffee, oil of euca- lyptus, mustard, clove, lemon juice, turpentine, tea and even fresh urine from camels or yaks are exam- ples of such components [66, 71, 72, 152]. It has been demonstrated that the concentration of PPD in some of these tattoos is higher than that allowed for hair dyes [153], even although the use of diaminobenzene derivatives is forbidden in skin dyes [68].
Contact allergies to PPD, and less frequently to es- sential oils in temporary tattoos are increasingly re- ported in children [66, 71, 72, 152]. These allergies may have consequences for their future, as certain professions become risky (for instance hairdressing)
in the case of PPD allergy, and potential problems with dark tanned clothing or hair dyes may follow.
Eczematous reactions are mostly seen at the site of the tattoo and they may be long-lasting. EEM-like [66] or lichenoid reactions [71] are also described.
Moreover, some patients may develop depigmenta- tion [71, 72] following the acute reaction, and this may persist for a period of several months up to over a year.
43.6.5 Toys
Preservatives in play gels have been described as causes of acute eczema on the hands; in the two cas- es, parabens were found to be the responsible aller- gens [154, 155]. Tosti [156], too, has described two girls who were sensitized by the preservatives meth- yl(chloro)isothiazolinone and 2-chloro-N-methyl- chloroacetamide in Plasticine.
Pevny and coworkers [16] observed a 14-year-old boy with hand eczema from a model kit, glue, and firearm accessories: positive patch tests were found with the plastic materials he had come into contact with and with benzoyl peroxide,p-tert-butyl cate- chol, and p-tert-butyl phenol (present in the glues), as well as to potassium dichromate in the gun oil.
Facial allergy due to contact with a cuddly toy [90]
and from balloons (see below) has been described.
An allergy to rubber from his basketball was also the cause of persistent hand eczema in a 9-year old boy [157].
Music playing may also provoke eczema: PPD used to stain the bow used to play the cello provoked eczematous lesions of the first three fingers of the right hand in an 11-year-old girl [158]. Colophony used as rosin for the bow or in the gripping powder used by gymnasts is also a possible allergen [120].
43.6.6 Rubber Items
Additives in the rubber of balloons may occasionally cause a facial dermatitis [2, 159], but they may also be responsible for dermatitis in elastic underwear, par- ticularly when bleached [160, 161], in a ball causing persistent hand eczema [157], in rubber sponges used to apply cosmetics [161], and in gloves [159] (al- though a preservative in the glove, cetyl pyridinium chloride, may be an exceptional allergen as well [162]). As with balloons, for example, type I allergic reactions may also occur, sometimes associated with a type IV reaction, as was the case in a 6-year-old boy who had undergone multiple surgical operations and who reacted to both gloves and a rubber dam used in
dentistry [163]. Moreover, contact urticaria syn- drome induced by natural rubber latex proteins is a frequent finding in such children, those suffering from spina bifida being particularly susceptible in this regard.
A particular type of diaper dermatitis reminiscent of a cowboy’s gunbelt holsters (hence the term “-
Lucky Luke”) was reported by Roul et al [55, 56]
(Fig. 2). The reaction was provoked by the rubber parts used for the new anti-leaking system in these diapers. The rubber parts were positive in all children and in some MBT, cyclohexyl thiophthalimide [57], and PTBP resin were probably present in the glue.
Rubber additives are also the main allergens re- sponsible for shoe dermatitis (see below).
Thiurams, mercapto chemicals and less common- ly carbamates are the responsible allergens in rubber allergy in children; thiourea derivatives in neoprene may also be the cause in for example goggles [172], trainers [120] and diving suits (own case). Polyure- thane is usually tolerated and IPPD used in industri- al rubbers is unlikely to be the cause [120].
43.6.7 Shoes and Clothes
Shoe dermatitis generally affects the back of the feet (Fig. 3). Mercaptobenzothiazole and thiuram deriva- tives, which are present not only in rubber shoes but
43
Fig. 2.“Lucky Luke” dermatitis from rubber derivatives in dia- pers
Fig. 3.Shoe dermatitis due to thiuram derivatives in an atopic child, complicated by a corticosteroid (triamcinolone-aceto- nide) contact allergy
also in certain glues [15, 124, 164], are important shoe allergens. Other potential culprits are PPD, which is also a possible dye allergen in socks [165], PPD deriv- atives such as diaminodiphenylmethane [164], and chromates [140, 166]. Trevistan and Kokelj [140] also consider dodecylmercaptane and thimerosal, used as a preservative in leather or leather cream, to be rele- vant shoe allergens. Topical medication was the most frequent cause of foot dermatitis in a retrospective study by Shackelford and Belsito [167], the allergens of which persist in shoe material for a long time. On the other hand, shoe allergens may persist in cotton socks even when they are washed.
When only the soles of the feet are affected, espe- cially the first toe and forefoot, particularly in atop- ics, juvenile plantar dermatosis is more likely.
In Italy, 51 (4.6%) out of 1098 children tested posi- tive to one or more disperse dyes used in synthetic clothes and especially to disperse yellow 3 and dis- perse orange 3. As only 17% of these children also were positive to PPD in the standard series, the au- thors suggest adding disperse dyes to the standard series [168].
43.6.8 Plastic Materials and Resins
Plastic toys as well as glues have been described as typical allergen sources for children [16] (see above).
para-Tertiary-butylphenol-formaldehyde (PTBPF) resin is the most frequently used phenol-formalde- hyde (PF) resin and is mainly used in neoprene-type adhesives and all-purpose glues.
Vincenzi and coworkers [169] reported the case of an adolescent with a linear vesicular dermatitis on the left leg caused by a glue in a knee-guard. There were positive patch tests to PTBPF and PF resins.
Shono and coworkers [170] observed four adoles- cents who reacted to these resins in an adhesive tape used for ankle support. One of them also reacted to sports shoes. It was also reported to be the cause of contact dermatitis to a limb prosthesis in a 5-year old boy [171], and is possibly used as a glue for electrodes to monitor sudden death in infants (personal obser- vation). Phenol-formaldehyde resin and benzoyl per- oxide were reported as the cause of contact allergy to swimming goggles in a 12-year old girl; dibutylthiou- rea in black neoprene rubber may also be the cause [172].
Epoxy resin was the cause of a dermatitis due to the glue used to fix kneepads in trousers [90] as well as an allergy to an identification band [51].
Not just the resins themselves, but also preserva- tives, such as benzalkonium chloride in plaster of Paris, may cause contact allergy [173].
43.6.9 Plants
Children often come into contact with plants while playing and do not know about their potential irri- tant, phototoxic (such as in giant hogweed) or aller- genic effects. In a review on plant dermatitis in Aus- tralia [174], children as well as gardeners were con- sidered at risk.
43.6.9.1 Poison Ivy, Poison Oak, Poison Sumac
Plants belonging to the Rhus family are the ones most often involved in allergic contact dermatitis among children living in northern California. Expo- sure can be direct or indirect (such as transfer of the allergen via pets), the latter being more difficult to diagnose [1]. Mallory [90] reports the possible pres- ence of black spots on the skin caused by the oleore- sin in poison ivy as a clue to its diagnosis.
43.6.9.2 Toxicodendron succedaneum (Rhus Tree)
Ten cases of phytophotodermatitis from Toxicoden- dron succedaneum in children under the age of 15 were reported in New Zealand. Generally, the face was involved [175].
Fig. 4.Allergic contact dermatitis from plastic toilet seat (pres- ence ofpara-tertiary-butylphenol-formaldehyde (PTBPF) res- in to which the child reacted upon patch testing, however, not confirmed)
43.6.9.3 Urtica urens
A combined contact urticarial and contact eczema- tous reaction on the hands and arms has been de- scribed by Edwards [176].
43.6.9.4 Asteraceae or Compositae
Wakelin and coworkers [177] reported the case of an atopic boy with exacerbations of his chronic eczema on the palmar side of his right, dominant hand. Patch tests revealed positivity to sesquiterpene lactones and to chrysanthemums, daisies, and dandelions, some of which he fed his rabbits.
Commens and coworkers [178] discussed the problem of Bindii (Soliva pterosperma) dermatitis, which is most often located on the palms, soles, knees and elbows, and tends to occur in Australian children (mainly boys who play sports) in the spring and ear- ly summer. The persistence for several months of er- ythematous papules, and sometimes also squamous and pustular lesions, has been ascribed to a residue of the allergenic seed in the skin. The differential di- agnoses include dermatitis herpetiformis.
43.6.9.5 Lichens
Wood and Rademaker [179] reported a facial derma- titis in an 8-year old atopic girl, which occurred whenever she climbed trees. Patch testing was posi- tive to lichens and usnic acid, thus indicating Parme- lia spp. as the sensitization source.
43.6.9.6 Gingko Fruit
Squashing the fruit of Gingko biloba or using it as marbles has been reported as a cause of allergic con- tact dermatitis in children in France [180].
43.6.9.7 Dioscorea batatas Decaisne
Kubo and coworkers [181] described the case of a 9- year-old girl who had accidentally touched her cheek with the rasped root of this plant, which resulted in the development of both an irritant and an allergic contact dermatitis.
43.6.9.8 Protein Contact Dermatitis
Oat-containing moisturizers are used for mainte- nance therapy in atopic dermatitis. Although allergic reactions to these products are rare, a protein contact dermatitis to avena extract has been reported by Paz- zaglia and co-workers [182].
43.6.9.9 Various Plant Materials
Fisher [60] has reported the occurrence of allergic reactions due to the presence of various plant com- ponents or extracts in topically applied products.
Moreover, as the use of herbal preparations is dra- matically increasing, contact allergy to “natural” in- gredients such as tea tree oil, especially when photo- aged (sun degraded),Calendula officinalis, and so on, is becoming more frequent [68].
43.6.10 Occupational Allergens
Among adolescents, certain occupational activities are likely to induce sensitization [23], particularly in hairdressers and construction workers [17, 29] and to a lesser extent in metal workers [17].
Pre-employment patch testing is not recommend- ed, although some authors advocate it, particularly with regard to metal allergy [183].
However, children like to help adults and this may also produce problems, as in the case reported by Co- razza and coworkers [184], who reacted to methyl- chloroisothiazolinone in a beeswax used to polish old wooden furniture.
쐽 Metals, ingredients of pharmaceutical products or cosmetics, rubber additives (in shoes, toys, diapers, sports equipment, and so on), plastics, resins (including those used in glues, orthopedic devices), and plants are allergens in children. In adoles- cents, sensitization via temporary tattoos or occupational allergens are also possible.
43
Core Message
43.7 Proposal for a Shortened Standard Series for Children
In view of the lack of chemical exposure of children compared to that of adults and the smaller patch test area, especially with younger children, Vigan [185]
and Brasch and Geier [31] proposed testing with an abbreviated standard patch test series of 16 allergens.
This was based on the results of four studies [17, 18, 23, 140]. Roul and coworkers [36] also suggest reduc- ing the number of tests: in children up to 6 years old a series of 17 allergens, and in older children a re- stricted European standard series of 29 allergens.
These tests have to be completed with allergens de- pending on the symptoms and localization of the dermatitis.
A multicenter retrospective study performed by the Réseau de Vigilance en Dermato-Allergologie (Revidal) created by the Groupe d’Etudes et de Re- cherche en Dermato-Allergologie (GERDA, France) examined the patch test results of 959 children below the age of 15 tested at 11 different centers from 1995 to 1997. The purpose of this study was mainly to deter- mine the usefulness of standard allergens in chil- dren.
The following ten allergens were tested in all cen- ters: potassium dichromate, neomycin, thiuram mix, formaldehyde, colophony, balsam of Peru, paraben mix, woolwax alcohols, fragrance mix, and nickel sul- fate. Other standard allergens were often tested too:
PPD, cobalt chloride, benzocaine, chinoform, IPPD, mercapto mix, mercaptobenzothiazole, PTBP-FR, epoxy resin, methyl(chloro)isothiazolinone, quater- nium-15, sesquiterpene lactone mix, and even pri- min.
The results [186] were as follows:
쐽 Primine: no reactions
쐽 Benzocaine, chinoform, IPPD, epoxy resin, quaternium-15, sesquiterpene lactone mix:
<1%
쐽 All other allergens: >1% of the patients tested.
This argues for the inclusion of PPD, cobalt chloride, mercapto mix, mercaptobenzothiazole, PTBP resin, and methyl(chloro)isothiazolinone in the standard series, because reactions to them occurred in more than 1% of patients tested.
IPPD and sesquiterpene lactone mix can be ex- cluded, which reduces the series to 16 standard aller- gens (Table 3). In cases where corticosteroids have been used, testing with corticosteroid allergy mark- ers, tixocortol pivalate 0.1% pet. and budesonide
0.1% pet. (besides the corticosteroids used by the pa- tient) is indicated. Of course, according to the specif- ic history and chemical environment of the patient, other substances should also be tested.
쐽 In children, an abbreviated standard series, supplemented with allergens suggested by the history, should be tested.
43.8 Conclusions
Contact allergy in children is more frequent than previously recognized. In an unselected population, for instance one consisting of schoolchildren, the prevalence is about 20%, while in a selected popula- tion (children suspected of contact allergy or suffer- ing from atopic or other types of dermatitis) the prevalence is found to be variable, for example relat- ed to geographical origin, with a mean of 40%.
Immunological differences between children (es- pecially neonates) and adults do exist, but their im- pact on the clinical development of contact allergy is still unknown. Although allergic contact dermatitis has occasionally been observed in neonates, it is gen- erally agreed that susceptibility to contact sensitiza-
Core Message
Table 3.Suggested abbreviated standard patch test series for children
1. Potassium dichromate 0.5% pet.
2. Neomycin 20% pet.
3. Thiuram mix 1% pet.
4. PPD-free base 1% pet.
5. Cobalt chloride 1% pet.
6. Formaldehyde 1% aq.
7. Colophony (colophonium) 20% pet.
8. Balsam of Peru (Myroxylon pereirae) 25% pet.
9. Woolwax alcohols (lanolin alcohol) 30% pet.
10. Mercapto mix 2% pet.
11. Paraben mix 16% pet.
12. PTBP-FR 1% pet.
13. Fragrance mix 8% pet.
14. Nickel sulfate 5% pet.
15. Chloromethyl- and methyl- 0.01% aq.
isothiazolinone
16. Mercaptobenzothiazole 2% pet.
tion and certainly also exposure to environmental al- lergens increase with the child’s age.
Whether allergic contact dermatitis is more or less frequently associated with atopy is still a matter of discussion. On the one hand, there is the reduced Th1 response in acute atopic eczema, so atopics are less likely to develop contact allergy; on the other hand, the damaged skin barrier facilitates allergen penetra- tion. The possibility of allergic contact dermatitis in atopic children must be considered, particularly if the distribution of the lesions is asymmetrical, when the dermatitis is located umbilically (nickel!), and when the dermatitis persists when being treated.
As with adults, the history and localization of the dermatitis are crucial for the diagnosis of allergic contact dermatitis, though certain contactants and/or habits that are characteristic of the child or the adolescent may be responsible for unusual clini- cal presentations.
Patch testing in children is safe; most authors think that irritant reactions are not frequently ob- served (except in atopics, particularly with metals) and that the same patch test concentrations as used in adults can be applied. However, the possibility of false-positive and false-negative reactions has to be considered and, if there is doubt, lower patch test concentrations should be tested later on.
Due to reduced test surface area, diminished envi- ronmental exposure to certain allergens and particu- larly hypermobility of young children, testing with an abbreviated standard series is recommended.
The most important allergens observed in this population are metals such as nickel (sometimes as- sociated with cobalt), particularly in girls, which is attributed to the popularity of cheap jewelry. The ex- tent to which hormonal factors play a role is still a matter of discussion. Mercury and its derivatives are still used as antiseptic agents in some countries, but the allergic reactions observed to them, even in young children, are often not clinically relevant. This is particularly true for thimerosal, for which vaccines have been regarded as the main sensitization source.
However, such an allergy does not seem to preclude future vaccinations, provided the tip of the needle is not contaminated and the injection is administered intramuscularly.
Other allergens identified in children mainly con- cern ingredients of pharmaceutical products and cosmetics (sometimes via another member of the household), rubber derivatives, which are often re- sponsible for shoe or diaper dermatitis, resins, and plants. Certain occupational allergens (such as those associated with hairdressing, construction, metal- working) are found in adolescents.
Suggested Reading
Brasch J, Geier J (1997) Patch test results in schoolchildren.
Contact Dermatitis 37 : 286–293
In a retrospective study in 22 German centers of the Ger- man Contact Dermatitis Research Group, the results from patch tests in children 6–15 years of age were analyzed. The allergens were related to sex and age. Nickel sulfate was the most important allergen (positive in 15.9% of all children), especially in older girls. Mercury components were the sec- ond most important group (thimerosal positive in 11.3% of all children tested), and especially important in the young- er age group (6–13 years); this was followed by fragrance al- lergens (fragrance mix positive in 8.2% of all children test- ed). For screening purposes a shortened standard series comprising nickel, cobalt, dichromate, thimerosal, fra- grance-allergens, wool wax alcohols, amerchol and methyl- chloro- and methylisothiazolinone, all of which produced positive tests in at least 1% of the tested children, was sug- gested.
Wahlberg JE, Goossens A (2001) Use of patch test concentra- tions for adults in children and their influence on test reac- tivity. Occup Environ Dermatol 49 : 97–101
A comparison between positive patch test results obtained in healthy children with non-eczematous dermatoses and those obtained in adults gave much higher percentages in children than in adults, which indicates that contact aller- gy was over-diagnosed in children. The authors favored the use of reduced test concentrations in children for allergens, such as potassium dichromate, nickel sulfate, formalde- hyde, and possibly also for rubber chemicals. A “wish list”
for improving patch testing in children includes: more studies in healthy children, comparison with in vitro tests, defined dosage and dilution series studies, as well as re- peated patch testing in order to demonstrate reproducibil- ity. For individual children, serial dilution tests, repeated testing, use tests (though difficult in children), but above all a clinical follow-up are useful if doubt exists about the patch test results.
References
1. Epstein E (1971) Contact dermatitis in children. Pediatr Clin North Am 18 : 839–852
2. Cronin E (1980) Contact dermatitis. Churchill Living- stone, Edinburgh, pp 20–21
3. Hjorth N (1981) Contact dermatitis in children. Acta Derm Venerol (Stockh) 95 : 36–39
4. Tennstedt D, Lachapelle JM (1987) Eczéma de contact al- lergique chez l´enfant. Bull Actual Thérap 32 : 3223–3228 5. Pevny I, Brennenstuhl M, Razinskas G (1984) Patch testing
in children (1). Contact Dermatitis 11 : 201–206
6. Marcussen PV (1963) Primary irritant patch-test reac- tions in children. Arch Dermatol 87 : 378–382
7. Mortz CG, Andersen KE (1999) Allergic contact derma- titis in children and adolescents. Contact Dermatitis 41 : 121–130
8. Weston WL, Weston JA (1984) Allergic contact dermatitis in children. Am J Dis Child 138 : 932–936
9. Weston WL,Weston JA, Kinoshita J, Kloepfer S, Carreon L, Toth S, Bullard D, Harper K, Martinez S (1986) Prevalence of positive epicutaneous tests among infants, children, and adolescents. Pediatrics 78 : 1070–1074
