**3.2.1 Metals**

#### Nickel

134 Contact Dermatitis

mistaken for condyloma (Robson et al., 2006). Finally, Jacquet's erosive diaper dermatitis describes perianal papules that are well-demarcated, sometimes umbilicated and red-purple in color (2-5mm diameter). They evolve into slow-healing erosions and ulcers (Paradisi et al., 2009) and may have elevated borders (Robson et al., 2006). This usually occurs in infants older than six months. Treatment of this entity can be difficult, but therapeutic options include topical treatment with antibiotics, miconazole, zinc oxide and non-steroidal ant-

Another relatively common form of irritant dermatitis in children is lip-licker's dermatitis. This presents as erythematous, scaly, thin plaques in a perioral distribution. Characteristically, the vermillion border is involved. It is caused by habitual licking of the lips and skin around the mouth and the irritant in this case is saliva. Atopy, wind and cold weather are predisposing factors. It is managed well with behavioral modification and topical emollients (i.e. petrolatum) acting as barriers from saliva. This entity should be differentiated from perioral dermatitis, which is an eruption of pink scaly papules that

As mentioned previously, the diagnosis of allergic dermatitis is more frequently being made in children. Tables 1 and 2 list the most common allergens detected in a series of investigations. A recent review evaluates 49 studies, most of which included symptomatic patients, finding the five most common allergens to be nickel sulfate, ammonium persulfate, gold sodium thiosulfate, thimerosal and toluene-2,5-diamine (Bonitsis et al., 2011). Table 3

Nickel **5-40%** (Goon et al., 2006; Seidenari et al., 2005) Mercury **6.4-25.3%** (Romaguera & Vilaplana, 1998; Wohrl et al., 2003)

Thimerosal **8.5-23%** (Manzini et al., 1998; Romaguera &

Cobalt **3.6-17.9% (**Shah et al., 1997; Zug et al., 2008) Wool alcohols **3.58-10.1%** (Manzini et al., 1998; Seidenari et al., 2005)

Balsam of peru **2.6-8% (**Clayton et al., 2006; Giordano-Labadie et al., 1999)

Fragrance **4.3-19%** (Rademaker & Forsyth, 1989;

Table 3. Prevalence of Common Allergens in Selected Populations

Potassium dichromate **8-21%** (Roul et al., 1999; Wilkowska et al., 1996)

Vilaplana, 1998)

Romaguera & Vilaplana, 1998)

**4-10%** (Beattie et al., 2007; Fernandez Vozmediano & Armario Hita, 2005)

generally spares the skin involving the vermillion (Leung & Robson, 2005).

inflammatory drugs (Paradisi et al., 2009).

**3.1.3 Lip-licker's dermatitis** 

**3.2 Allergic contact dermatitis** 

provides prevalence rates of common allergens.

Rubber chemicals (including carba

mix & thiuram)

**Allergen Prevalence** 

Nickel is the most widespread allergen in the general population (Heim & McKean, 2009; Johnke et al., 2004) and is most often identified as the leading allergen in children (Tables 1 & 2). It accounts for up to 14.9% of positive patch tests (Dotterud and Falk, 1995) in asymptomatic children and is generally more frequent in females (Beattie et al., 2007; Brasch & Geier, 1997; Giordano-Labadie et al., 1999). Importantly, young infants may also be sensitized to nickel. In a study of 543 infants followed from birth to age 18 months, 8.6% showed a reproducible positive reaction to this metal (Johnke et al., 2004). Ear piercing is often considered the major risk factor for becoming sensitized to nickel (Smith-Sivertsen et al., 1999). Other sources include everyday items such as jewelry, eyeglass frames, belt buckles, jean snaps, zippers, coins, keys and even cell phones (Hsu et al., 2010). Another potential cause for sensitization is orthodontic devices (Temesvari & Racz, 1988; Veien et al., 1994). In this setting, the allergic contact dermatitis can present as cheilitis, perioral eczema and stomatitis. Other metals are also implicated in this setting including potassium dichromate (Veien et al., 1994). Typical locations for nickel dermatitis include the face, earlobes, wrist, neck and periumbilical skin with the last site being most common (Hsu et al., 2010).

While a localized contact dermatitis is most expected with nickel, id reactions may not be uncommon. Id reaction refers to involvement of skin lacking direct contact with the allergen, resulting from auto-sensitization from circulating immune cells. Such eruptions, sometimes confused with atopic dermatitis, present as pruritic papules distributed on the upper arms, thighs, knees and elbows. They tend to be more persistent than localized contact dermatitis, lasting up to months after localized plaques have cleared (Hsu et al., 2010). Silverberg and colleagues examined 30 pediatric patients with personal history of umbilical or wrist dermatitis or a family history of nickel allergic contact dermatitis. All patients developed a positive patch test to nickel and 50% of patients were reported to develop id reactions (Silverberg et al., 2002). Systemic contact dermatitis has also been reported with nickel. It may present as a generalized dermatitis despite contact with nickel at a limited body site. In some cases, it may result from oral ingestion of nickel, including the small amount that is present in foods and tap water (Hsu et al., 2010).

#### Cobalt

While a significant percentage of positive patch test results in children are attributed to cobalt, it should be recognized that this metal often co-sensitizes with other metals, particularly nickel and potassium dichromate (Goon & Goh, 2006; Lisi et al., 2003). At times, contamination of cobalt patch tests with nickel may also lead to false positive tests (Lisi et al., 2003). Yet, cobalt itself remains relevant for allergic contact dermatitis. One study attributes 2 of 17 cases of pediatric hand dermatitis to cobalt (Beattie et al., 2007). In 1971, a case was reported of an 11-year-old boy who presented with eczematous lesions at the site of his eyeglass frames, wrists and mouth. His dermatitis was attributed to cobalt in his watch, glasses and the ball point pen that he chewed (Grimm, 1971).

#### Potassium dichromate

A common source for potassium dichromate exposure in children is its use in tanning leather, particularly in shoes (Sarma and Ghosh, 2010; Weston et al., 1986). In such cases, the

Contact Dermatitis in Children 137

solutions and eardrops. However, its clinical relevance is often questioned, as most sensitized patients deny a history of dermatitis. High rates of sensitization are likely due to the presence of this compound in mandatory vaccines that were used in the past (Osawa et al., 1991; Schafer et al., 1995). Possibly, thimerosal sensitization is relevant in a subset of children affected by atopic dermatitis. Patrizi and colleagues described a series of five children who developed diffuse atopic dermatitis flares, starting at injection sites, within days of vaccination with thimerosal-containing vaccines. External contamination of the

Neomycin is present in many topical preparations including ear and eye drops that are used to treat bacterial infections. In 1979, Leyden and Kligman reported that intermittent use of the agent was not associated with excessive sensitization, as only 1 of 653 subjects less than 12 years old was sensitive to neomycin (Leyden & Kligman, 1979). Since then, however, others have supported its status as a relevant contact allergen (Mortz & Andersen, 1999). In 1986, Weston identified it as the most common allergen causing positive patch test results and attributed this to the prominent use of this agent for bacterial infections and diaper

A number of other pharmaceutical agents and preservatives have been implicated in allergic contact dermatitis, though to a lesser degree than thimerosal and neomycin. These include ethylenediamine, a chemical stabilizer used in Mycolog cream (nystatin and triamcinolone cream) used to treat various skin conditions including diaper dermatitis. It too has been reported as one of the most common causes of positive patch testing in children (Balato et al, 1989). Ethylenediamine can cross react with antihistamines to produce severe systemic reactions. Benzoyl Peroxide is occasionally found among lists of most common allergens (Table 1), but Heine et al. warn that when the adult concentrations of this agent are applied to children during patch testing, false positive reactions can occur due to the agent's irritant potential (Heine et al., 2004). Corticosteroids have been implicated in pediatric allergic contact dermatitis in multiple case reports (Cunha et al., 2003; Luigi et al., 2001). It is recommended that the standard corticosteroid series as well as any agents being used by the child be patch tested when allergic contact dermatitis is suspected in the setting of topical steroid use (Luigi et al., 2001). Less common pharmaceutical allergens have also been reported in children. In 2008, the first case of chlorhexadine allergic contact dermatitis was described in a 4-year-old boy (de Waard-van der Spek & Oranje, 2008). Another case of chlorhexadine contact dermatitis was reported in a 23-month-old with a wound cleaned with this agent. Interestingly, the patient's mother reported that chlorhexadine had been prescribed for umbilical cord care at birth. This case may suggest that sensitization occurred

In present day, cosmetics are being marketed towards children (Kutting et al., 2004). Though industry guidelines exist regarding safe or hypoallergenic compounds, in some instances, these recommendations are not adhered to in made-for-children cosmetics (Rastogi et al.,

needles is often blamed as a cause for sensitization (Patrizi et al., 1999).

Neomycin

dermatitis (Weston et al., 1986).

within days to weeks of birth (Le Corre et al., 2010).

**3.2.3 Skin care products & fragrances** 

Other pharmaceuticals

distribution of dermatitis is typically located at the dorsal feet and occasionally at the plantar surfaces. Though, if only the plantar surfaces are involved, the diagnosis of juvenile plantar dermatosis should also be considered. Other items that contain potassium dichromate include cement, matches, bleaches, antirust compounds, varnishes, yellow paints, spackling compounds and certain glues (Fisher et al., 2008). While many of these items are encountered more so in occupational exposures, these items could potentially exist in a child's home environment or relate to adolescent hobbies.

#### Mercury

Sensitization to mercury is relatively common. It is also thought to cross react with thimerosal, a compound that contains mercury. Sources of exposure include shoes in which mercury is used as a preservative, and more classically antiseptic solutions (Fernandez Vozmediano & Armario Hita, 2005). Other items that may contain mercurial agents are eye drops, depigmenting creams, pediculosis preparations, vaccines, broken thermometers, amalgam fillings, contact lens solutions and pesticides (Goossens & Morren, 2004). Another presentation for mercury contact allergy is' baboon syndrome'. This entity was described by Andersen et al. in 1984 and is characterized by a systemic contact dermatitis that involves a pruritic and confluent macular and papular light-red eruption localized to the gluteal cleft and major flexures. It can result from contact with various allergens, but mercury is a classic cause. The most common exposure to mercury has been via inhalation from broken thermometers (Lerch & Bircher, 2004). The use of such thermometers has greatly diminished over the years.

#### Other metals

Less common metal allergens include aluminum, iron, copper and palladium. The development of pruritic nodules at hyposensitization therapy injection sites has been attributed to aluminum. In one study, 8 of 37 children who underwent this therapy showed a contact allergy to aluminum (Netterlid et al., 2009). Iron is considered a rare cause of allergic contact dermatitis, though one case describing a 7-year-old boy with an iron allergy related to his orthopedic prosthesis has been reported (Hemmer et al., 1996). Copper is also an infrequent allergen, but dental amalgam has been associated with positive copper patch testing thought to be clinically relevant (Wohrl et al., 2003). Allergy to palladium may be attributed to jewelry (Goossens, 2008). In a 1996 study, 7% of 700 adolescents had positive patch tests to palladium. Except for three subjects, they demonstrated positive testing to nickel as well, suggesting co- or cross-sensitization (Kanerva et al., 1996). The importance of palladium alone as a relevant contact allergen is controversial. Similarly, despite a review reporting gold sodium thiosulfate to be a common allergen resulting in positive patch testing, its clinical relevance is debated (Bonitsis et al., 2011). Many who test positive to this allergen can wear gold jewelry without developing a reaction (Andersen & Jensen, 2007).

#### **3.2.2 Pharmaceuticals**

#### Thimerosal

Thimerosal is composed of two allergenic compounds, mercury and thiosalicylic acid, and is among the most common causes for positive patch testing in pediatric studies (Tables 1 & 2). It is used as a preservative in vaccines, antitoxins, ophthalmic preparations, contact lens solutions and eardrops. However, its clinical relevance is often questioned, as most sensitized patients deny a history of dermatitis. High rates of sensitization are likely due to the presence of this compound in mandatory vaccines that were used in the past (Osawa et al., 1991; Schafer et al., 1995). Possibly, thimerosal sensitization is relevant in a subset of children affected by atopic dermatitis. Patrizi and colleagues described a series of five children who developed diffuse atopic dermatitis flares, starting at injection sites, within days of vaccination with thimerosal-containing vaccines. External contamination of the needles is often blamed as a cause for sensitization (Patrizi et al., 1999).

#### Neomycin

136 Contact Dermatitis

distribution of dermatitis is typically located at the dorsal feet and occasionally at the plantar surfaces. Though, if only the plantar surfaces are involved, the diagnosis of juvenile plantar dermatosis should also be considered. Other items that contain potassium dichromate include cement, matches, bleaches, antirust compounds, varnishes, yellow paints, spackling compounds and certain glues (Fisher et al., 2008). While many of these items are encountered more so in occupational exposures, these items could potentially exist

Sensitization to mercury is relatively common. It is also thought to cross react with thimerosal, a compound that contains mercury. Sources of exposure include shoes in which mercury is used as a preservative, and more classically antiseptic solutions (Fernandez Vozmediano & Armario Hita, 2005). Other items that may contain mercurial agents are eye drops, depigmenting creams, pediculosis preparations, vaccines, broken thermometers, amalgam fillings, contact lens solutions and pesticides (Goossens & Morren, 2004). Another presentation for mercury contact allergy is' baboon syndrome'. This entity was described by Andersen et al. in 1984 and is characterized by a systemic contact dermatitis that involves a pruritic and confluent macular and papular light-red eruption localized to the gluteal cleft and major flexures. It can result from contact with various allergens, but mercury is a classic cause. The most common exposure to mercury has been via inhalation from broken thermometers (Lerch & Bircher, 2004). The use of such thermometers has greatly

Less common metal allergens include aluminum, iron, copper and palladium. The development of pruritic nodules at hyposensitization therapy injection sites has been attributed to aluminum. In one study, 8 of 37 children who underwent this therapy showed a contact allergy to aluminum (Netterlid et al., 2009). Iron is considered a rare cause of allergic contact dermatitis, though one case describing a 7-year-old boy with an iron allergy related to his orthopedic prosthesis has been reported (Hemmer et al., 1996). Copper is also an infrequent allergen, but dental amalgam has been associated with positive copper patch testing thought to be clinically relevant (Wohrl et al., 2003). Allergy to palladium may be attributed to jewelry (Goossens, 2008). In a 1996 study, 7% of 700 adolescents had positive patch tests to palladium. Except for three subjects, they demonstrated positive testing to nickel as well, suggesting co- or cross-sensitization (Kanerva et al., 1996). The importance of palladium alone as a relevant contact allergen is controversial. Similarly, despite a review reporting gold sodium thiosulfate to be a common allergen resulting in positive patch testing, its clinical relevance is debated (Bonitsis et al., 2011). Many who test positive to this allergen can wear gold jewelry without developing a reaction (Andersen & Jensen, 2007).

Thimerosal is composed of two allergenic compounds, mercury and thiosalicylic acid, and is among the most common causes for positive patch testing in pediatric studies (Tables 1 & 2). It is used as a preservative in vaccines, antitoxins, ophthalmic preparations, contact lens

in a child's home environment or relate to adolescent hobbies.

Mercury

diminished over the years.

**3.2.2 Pharmaceuticals** 

Thimerosal

Other metals

Neomycin is present in many topical preparations including ear and eye drops that are used to treat bacterial infections. In 1979, Leyden and Kligman reported that intermittent use of the agent was not associated with excessive sensitization, as only 1 of 653 subjects less than 12 years old was sensitive to neomycin (Leyden & Kligman, 1979). Since then, however, others have supported its status as a relevant contact allergen (Mortz & Andersen, 1999). In 1986, Weston identified it as the most common allergen causing positive patch test results and attributed this to the prominent use of this agent for bacterial infections and diaper dermatitis (Weston et al., 1986).

#### Other pharmaceuticals

A number of other pharmaceutical agents and preservatives have been implicated in allergic contact dermatitis, though to a lesser degree than thimerosal and neomycin. These include ethylenediamine, a chemical stabilizer used in Mycolog cream (nystatin and triamcinolone cream) used to treat various skin conditions including diaper dermatitis. It too has been reported as one of the most common causes of positive patch testing in children (Balato et al, 1989). Ethylenediamine can cross react with antihistamines to produce severe systemic reactions. Benzoyl Peroxide is occasionally found among lists of most common allergens (Table 1), but Heine et al. warn that when the adult concentrations of this agent are applied to children during patch testing, false positive reactions can occur due to the agent's irritant potential (Heine et al., 2004). Corticosteroids have been implicated in pediatric allergic contact dermatitis in multiple case reports (Cunha et al., 2003; Luigi et al., 2001). It is recommended that the standard corticosteroid series as well as any agents being used by the child be patch tested when allergic contact dermatitis is suspected in the setting of topical steroid use (Luigi et al., 2001). Less common pharmaceutical allergens have also been reported in children. In 2008, the first case of chlorhexadine allergic contact dermatitis was described in a 4-year-old boy (de Waard-van der Spek & Oranje, 2008). Another case of chlorhexadine contact dermatitis was reported in a 23-month-old with a wound cleaned with this agent. Interestingly, the patient's mother reported that chlorhexadine had been prescribed for umbilical cord care at birth. This case may suggest that sensitization occurred within days to weeks of birth (Le Corre et al., 2010).

#### **3.2.3 Skin care products & fragrances**

In present day, cosmetics are being marketed towards children (Kutting et al., 2004). Though industry guidelines exist regarding safe or hypoallergenic compounds, in some instances, these recommendations are not adhered to in made-for-children cosmetics (Rastogi et al.,

Contact Dermatitis in Children 139

oxybenzone, in a 6-year-old (Cook & Freeman, 2002). Recently, octocrylene, a solar filter from the cinnamate family, has been used as a sunscreen against UVB and near-UVA range. It was initially considered to be non-allergenic (Delplace & Blondeel, 2006). But even this agent has caused positive patch tests in 10 of 11 children tested (Avenel-Audran et al., 2010). Not all sunscreen ingredients that can cause allergy are active ingredients. Chu and Sun reported a case of contact allergy to triethanolamine, an emulsifier in sunscreens, in an 8-

A somewhat controversial allergen in adults and children is lanolin, containing wool alcohols. It is found in many skin care products such as Aquaphor Healing Ointment ® (AHO), an emollient commonly used in atopic children. Though previously thought to be a pertinent allergen, in 1998, Kligman wrote that lanolin was "at most a weak contact allergen" and that many case reports represented false positives (Kligman, 1998). However, a few large scale epidemiologic studies list wool alcohols as one of the most common allergens in children (Tables 1 and 2). Epidemiologic data in adults suggests that over time, positive patch testing to lanolin is in fact decreasing (Warshaw et al., 2009). However, in 2010, Matiz and Jacob reported that at least two children who reported burning or irritation to AHO and tested negative to commercially prepared lanolin (one to the T.R.U.E. test and one to Allergeaze) also tested positive to lanolin 30% in petrolatum (Beiersdorf) and their own AHO product (Matiz & Jacob, 2010). These conflicting opinions may not be cause to stop recommending agents that contain lanolin, but rather, a reason for suspicion of allergy

Natural rubber (latex) itself is most often associated with a type I hypersensitivity reaction, which is characterized by urticaria and, in severe cases, anaphylaxis. However, many rubber additives are responsible for type IV hypersensitivity in the form of allergic contact dermatitis. These include accelerators such as thiurams, carbamates, thioureas and mercaptobenzothiazoles (MBTs) and antioxidants such as para-phenylenediamine (PPD) derivatives, which retard environmental degradation (Fisher et al., 2008.) These additives can result in a variety of clinical presentations. The face may be affected after contact with balloons. Eruptions at the waistline have occurred in response to elastic underwear and rubber sponges. Balls and gloves may cause chronic hand eczema (Goossens & Morren, 2004).There is also at least one case report of co-existent type I and type IV sensitivity to

In Beattie et al's study, it was reported that thiuram mix and PPD were each responsible for one case of hand dermatitis (from a total of 17 cases). In the same study, of five cases of foot dermatitis with relevant positive patch tests, two were attributed to mercapto mix and MBT and one to PPD. Such dermatoses are attributed to the presence of these agents in rubber shoe components. Shoe dermatitis that is attributed to allergic contact typically presents as a pruritic papular exanthem on the dorsum of the toes, sparing the webspaces (Sharma

A new pattern for allergic contact dermatitis has been attributed to anti-leak diapers, which feature elastic bands at the thighs that are quite tight. These diapers cause a characteristic distribution of dermatitis at the outer buttocks and hips in toddlers, which resembles a

if parents report a reaction or if a patient's dermatitis is not improving.

rubber latex in a 6-year-old dental patient (Placucci et al., 1996)).

year-old girl (Chu & Sun, 2001).

**3.2.4 Rubber chemicals** 

&Asati, 2010).

1999). Kohl and colleagues patch tested 70 children suspected of having allergic contact dermatitis. In total, 48.6% of them patch tested positive, with cosmetics being the number one cause for sensitization (Kohl et al., 2002). The specific allergens responsible for sensitization in cosmetics are diverse but include fragrances and dyes. Ammonium persulfate and toluene-2,5,diamine are allergens in hair dyes, and interestingly, children often patch test positive to these agents (Bonitsis et al., 2007). Preservatives, including formaldehyde and formaldehyde releasers, are also considered relevant allergens in cosmetics, with Kathon CG being the most common preservative to patch test positive in one study (Conti et al., 1997). Interestingly, not all of children's exposure to cosmetics is direct, but may be related to agents used by caretakers. Fisher reported a 7-year-old girl with an allergy to cinnamic aldehyde who presented with cheilitis and periorbital dermatitis caused by her mother's lipstick (Fisher, 1995).

Symptomatic children frequently exhibit positive patch testing to fragrances, as elucidated by several recent studies (Clayton et al., 2006; Hogeling & Pratt, 2008; Milingou et al., 2010; Zug et al., 2010). A particularly important diagnostic tool is the 'Fragrance Mix' patch test, which contains three cinnamic derivatives, two eugenol derivatives, geraniol, hydroxycitronellal and oak moss absolute extract. Fragrances are nearly ubiquitous, as they are present in many products including cosmetics, toiletries, soaps, laundry detergents, cleansers, rubber, plastic, paper and textiles (Johansen, 2002). Allergic contact dermatitis due to fragrances may present in either a localized or generalized distribution, and facial dermatitis is more common in those with fragrance contact allergy compared to those without. In adolescent patients, axillary exanthem may indicate a fragrance allergy due to use of deodorants (Johansen, 2002).

Balsam of peru is a plant-derived allergen that is present in many topical medications and cosmetics due to its aromatic properties. It has marginal bacteriocidal activity and is used in toothpastes, cough lozenges and dental cements. It is not an uncommon cause of sensitization in infants and children (Fisher et al., 2008) and is found to be one of the most frequent causes of positive patch testing in children (Kuiters et al., 1989; Jacob et al., 2008; Romaguera et al., 1998; Roul et al., 1999). The face is a common site of involvement (Edman, 1985).

Other rising causes of allergic contact dermatitis, which could be avoided in children, are natural remedies. Oftentimes, these agents are presumed safe because they are 'natural' but in fact, several have been linked to dermatitis (Kutting et al., 2004). For example, tea tree oil derived from the Melaleuca alternifolia cheel is considered a treatment for many skin conditions including infections and acne (Allen, 2001; Bedi & Shenefelt, 2002). It contains approximately 100 components which are generally in low enough concentrations so as not to induce allergy (Kutting et al., 2004). However, when photoaged, tea tree oil becomes a stronger sensitizer due to formation of monoterpene breakdown products (Hausen et al., 1999).

Another skin care product particularly pertinent to the field of dermatology is sunscreen. Much data regarding the allergic potential of sunscreens is in adults. However, there are multiple agents which are reported to cause contact allergy in children as well. Though photoallergy is generally uncommon in children, Cook and Freeman described a case of photoallergic contact dermatitis to two sunscreen agents, methoxycinnamate and

1999). Kohl and colleagues patch tested 70 children suspected of having allergic contact dermatitis. In total, 48.6% of them patch tested positive, with cosmetics being the number one cause for sensitization (Kohl et al., 2002). The specific allergens responsible for sensitization in cosmetics are diverse but include fragrances and dyes. Ammonium persulfate and toluene-2,5,diamine are allergens in hair dyes, and interestingly, children often patch test positive to these agents (Bonitsis et al., 2007). Preservatives, including formaldehyde and formaldehyde releasers, are also considered relevant allergens in cosmetics, with Kathon CG being the most common preservative to patch test positive in one study (Conti et al., 1997). Interestingly, not all of children's exposure to cosmetics is direct, but may be related to agents used by caretakers. Fisher reported a 7-year-old girl with an allergy to cinnamic aldehyde who presented with cheilitis and periorbital dermatitis

Symptomatic children frequently exhibit positive patch testing to fragrances, as elucidated by several recent studies (Clayton et al., 2006; Hogeling & Pratt, 2008; Milingou et al., 2010; Zug et al., 2010). A particularly important diagnostic tool is the 'Fragrance Mix' patch test, which contains three cinnamic derivatives, two eugenol derivatives, geraniol, hydroxycitronellal and oak moss absolute extract. Fragrances are nearly ubiquitous, as they are present in many products including cosmetics, toiletries, soaps, laundry detergents, cleansers, rubber, plastic, paper and textiles (Johansen, 2002). Allergic contact dermatitis due to fragrances may present in either a localized or generalized distribution, and facial dermatitis is more common in those with fragrance contact allergy compared to those without. In adolescent patients, axillary exanthem may indicate a fragrance allergy due to

Balsam of peru is a plant-derived allergen that is present in many topical medications and cosmetics due to its aromatic properties. It has marginal bacteriocidal activity and is used in toothpastes, cough lozenges and dental cements. It is not an uncommon cause of sensitization in infants and children (Fisher et al., 2008) and is found to be one of the most frequent causes of positive patch testing in children (Kuiters et al., 1989; Jacob et al., 2008; Romaguera et al., 1998; Roul et al., 1999). The face is a common site of involvement

Other rising causes of allergic contact dermatitis, which could be avoided in children, are natural remedies. Oftentimes, these agents are presumed safe because they are 'natural' but in fact, several have been linked to dermatitis (Kutting et al., 2004). For example, tea tree oil derived from the Melaleuca alternifolia cheel is considered a treatment for many skin conditions including infections and acne (Allen, 2001; Bedi & Shenefelt, 2002). It contains approximately 100 components which are generally in low enough concentrations so as not to induce allergy (Kutting et al., 2004). However, when photoaged, tea tree oil becomes a stronger sensitizer due to formation of monoterpene

Another skin care product particularly pertinent to the field of dermatology is sunscreen. Much data regarding the allergic potential of sunscreens is in adults. However, there are multiple agents which are reported to cause contact allergy in children as well. Though photoallergy is generally uncommon in children, Cook and Freeman described a case of photoallergic contact dermatitis to two sunscreen agents, methoxycinnamate and

caused by her mother's lipstick (Fisher, 1995).

use of deodorants (Johansen, 2002).

breakdown products (Hausen et al., 1999).

(Edman, 1985).

oxybenzone, in a 6-year-old (Cook & Freeman, 2002). Recently, octocrylene, a solar filter from the cinnamate family, has been used as a sunscreen against UVB and near-UVA range. It was initially considered to be non-allergenic (Delplace & Blondeel, 2006). But even this agent has caused positive patch tests in 10 of 11 children tested (Avenel-Audran et al., 2010). Not all sunscreen ingredients that can cause allergy are active ingredients. Chu and Sun reported a case of contact allergy to triethanolamine, an emulsifier in sunscreens, in an 8 year-old girl (Chu & Sun, 2001).

A somewhat controversial allergen in adults and children is lanolin, containing wool alcohols. It is found in many skin care products such as Aquaphor Healing Ointment ® (AHO), an emollient commonly used in atopic children. Though previously thought to be a pertinent allergen, in 1998, Kligman wrote that lanolin was "at most a weak contact allergen" and that many case reports represented false positives (Kligman, 1998). However, a few large scale epidemiologic studies list wool alcohols as one of the most common allergens in children (Tables 1 and 2). Epidemiologic data in adults suggests that over time, positive patch testing to lanolin is in fact decreasing (Warshaw et al., 2009). However, in 2010, Matiz and Jacob reported that at least two children who reported burning or irritation to AHO and tested negative to commercially prepared lanolin (one to the T.R.U.E. test and one to Allergeaze) also tested positive to lanolin 30% in petrolatum (Beiersdorf) and their own AHO product (Matiz & Jacob, 2010). These conflicting opinions may not be cause to stop recommending agents that contain lanolin, but rather, a reason for suspicion of allergy if parents report a reaction or if a patient's dermatitis is not improving.

#### **3.2.4 Rubber chemicals**

Natural rubber (latex) itself is most often associated with a type I hypersensitivity reaction, which is characterized by urticaria and, in severe cases, anaphylaxis. However, many rubber additives are responsible for type IV hypersensitivity in the form of allergic contact dermatitis. These include accelerators such as thiurams, carbamates, thioureas and mercaptobenzothiazoles (MBTs) and antioxidants such as para-phenylenediamine (PPD) derivatives, which retard environmental degradation (Fisher et al., 2008.) These additives can result in a variety of clinical presentations. The face may be affected after contact with balloons. Eruptions at the waistline have occurred in response to elastic underwear and rubber sponges. Balls and gloves may cause chronic hand eczema (Goossens & Morren, 2004).There is also at least one case report of co-existent type I and type IV sensitivity to rubber latex in a 6-year-old dental patient (Placucci et al., 1996)).

In Beattie et al's study, it was reported that thiuram mix and PPD were each responsible for one case of hand dermatitis (from a total of 17 cases). In the same study, of five cases of foot dermatitis with relevant positive patch tests, two were attributed to mercapto mix and MBT and one to PPD. Such dermatoses are attributed to the presence of these agents in rubber shoe components. Shoe dermatitis that is attributed to allergic contact typically presents as a pruritic papular exanthem on the dorsum of the toes, sparing the webspaces (Sharma &Asati, 2010).

A new pattern for allergic contact dermatitis has been attributed to anti-leak diapers, which feature elastic bands at the thighs that are quite tight. These diapers cause a characteristic distribution of dermatitis at the outer buttocks and hips in toddlers, which resembles a

Contact Dermatitis in Children 141

Rademaker purported that the value was as high at 92% (Kuiters et al., 1989; Rademaker et al., 1989). A review of studies that report on relevance suggests that the value is probably around 60% (Table 1). Many authors specifically endorse the use of patch testing in children (Jacob et al., 2008; Worm et al., 2007). In the past, it was recommended that the concentration of patch tests be reduced in children (Fisher, 1975; Hjorth, 1981). For example, Fisher recommended using half the recommended concentration (Fisher, 1975). This was due the concern that children are at higher risk of developing irritant reactions and thus, false positive tests (Mortz & Andersen, 1999). However, recent studies suggest that the incidence of irritant reactions is low. Brasch and Geier reported a 9% incidence of irritant reactions (Brasch & Geier, 1997). Most experts recommend the use of the same allergen concentration in children as in adults (Brasch & Geier, 1997; Mortz & Andersen,

Multiple groups recommend abbreviated series in children, in part due to smaller body surface area of normal skin on which to perform the testing. The German Contact Dermatitis Research Group suggests that in children aged 6-12 years old, the following allergens should be tested: nickel sulfate, thiuram mix, colophony, mercaptobenzothiazole, fragrance mix I, fragrance mix II, mercapto mix, bufexamac, dibromodicyanobutane, chlormethylisothiazolinone, neomycin and Compositae mix. Potassium dichromate, wool alcohols, disperse blue mix, para-phenylenediamine and *p-tert*.-butylphenol-formaldehyde resin may be added if clinically indicated (Worm et al., 2007). Brasch and Geier advocate for a shorter series that includes nickel, cobalt, dichromate, thimerosal, fragrance allergens, wool wax alcohols and Kathon CG. Their analysis was conducted in Germany, and they suggest that since different geographic locations may show varying rates of sensitization to allergens, local experience should be considered when choosing patch testing series for children (Brasch & Geier, 1997). Finally, Seidenari et al. advise clinicians to use patch testing in children but warn that due to frequent changes in relevant allergen exposures, periodic evaluations of the appropriate testing trays should be done for the pediatric population

Of note, it should be mentioned that while patch testing often yields positive results to relevant allergens, it is unclear that finding a positive allergen is associated with improved clinical outcome. This is generally due to lack of data. Moustafa et al. recently published retrospective data supporting the relevance of positive patch tests in 44% of 110 children. Unfortunately, finding a positive allergen was not associated with improved clinical

In adults, it has been shown that performing delayed patch test readings often yields more positive results. Matiz and colleagues have recently proposed that this is true in children as well. In 38 children aged 6 -17 years old, patch tests were evaluated after 48 hours, 72-96 hours and again at 7-9 days. 50% of children revealed positive reactions at the 7-9 day mark and 13% of the total number of children revealed new late delayed reactions. 4 of 6 late delayed allergens were considered clinically relevant including quaternium 15, formaldehyde, diazolidinyl urea and *p-tert*-butylphenol formaldehyde resin (Matiz et al., 2011). While this may not be a feasible approach to patch testing in all patients, it is a useful pearl in children for whom a diagnosis of allergic contact dermatitis

1999; Roul et al., 1997; Worm, 2006).

(Seidenari et al., 2005).

is highly suspected.

outcome in this population (Moustafa et al., 2011).

gunbelt holster. The term 'Lucky Luke' is used to describe this entity that has been attributed to MBT, BPF (Roul et al., 1998) and recently cyclohexylthiophathalimide, which is used as a vulcanization retarder in rubber (Belhadjali et al., 2001).
