**3.1.1 Diaper dermatitis**

The term 'diaper dermatitis' refers to a multifactorial eruption in the region of the diaper and should not be confused with other diseases that are aggravated by diapers or occur in the same distribution (Scheinfeld, 2005). Factors contributing to primary diaper dermatitis include increased skin moisture and wetness, which create a warm and humid environment that makes infant skin more susceptible to breakdown and more permeable to chemicals

extracurricular activities. Consider the case of an 11-year-old female cellist with a three year history of an eruption on the right first, second and third digits. She patch tested positive to para-phenylenediamine, which the manufacturer of her bow verified was present in the

The association between atopic dermatitis and allergic contact dermatitis remains somewhat unclear. Several older studies that specifically investigated the prevalence of positive patch testing in children with atopic dermatitis suggested that contact allergy is less common in this population (Angelini & Meneghini, 1977). Jones et al. investigated sensitivity to Rhus in atopic and non-atopic patients. Patch tests to Rhus were positive in 61% of healthy patients and only 15% of those with atopic dermatitis (Jones et al., 1973). This correlation may be explained, as contact allergy is a Th1 response and atopic dermatitis patients have a decreased Th1 response (Mortz & Anderson, 1999). Alternatively, some studies suggest that allergic contact dermatitis is more frequent in atopic patients. Epstein and colleagues evaluated the frequency of positive patch tests in patients with atopic dermatitis versus those with psoriasis. Twenty-eight percent of those with atopic dermatitis had positive reactions versus 9% of those with psoriasis (Epstein & Mohajerin, 1964). Another study showed that patch tests were more frequently positive in those with atopic dermatitis versus controls without atopic dermatitis but with other allergic disease including allergic conjunctivitis and asthma (Lammintausta et al., 1992). Dotterud and Falk reported positive tests were significantly more common in schoolchildren with atopic dermatitis, 28.8%, versus 17.9% in controls (Dotterud & Falk, 1995). One explanation for increased risk in atopic patients is their defective skin barrier, which allows for increased exposure to antigens. Also, atopic patients may become sensitized to more allergens given their frequent use of topical agents including emollients, which often contain fragrances and preservatives (Mortz and Anderson, 1999). It should also be considered that atopic skin is readily irritated, which may lead to false positive patch testing results, especially in the case of metals (Dotterud & Falk, 1994). The latter concept is important as some recent studies did not detect a difference in the prevalence of positive patch testing between children with and

without atopic dermatitis (Balato et al., 1989; Motolese et al., 1995).

There are two categories of contact dermatitis that affect the pediatric population: irritant and allergic contact dermatitis. Irritant dermatoses have been diagnosed in children for

The term 'diaper dermatitis' refers to a multifactorial eruption in the region of the diaper and should not be confused with other diseases that are aggravated by diapers or occur in the same distribution (Scheinfeld, 2005). Factors contributing to primary diaper dermatitis include increased skin moisture and wetness, which create a warm and humid environment that makes infant skin more susceptible to breakdown and more permeable to chemicals

**3. Common causes of contact dermatitis in children** 

bow stain (O'Hagan and Bingham, 2001).

**2.5 Atopic dermatitis** 

**3.1 Irritant dermatitis** 

**3.1.1 Diaper dermatitis** 

many years, particularly diaper dermatitis.

and enzymes. An elevated pH results when bacterial ureases split urea in the urine to release ammonia, and this predisposes infant skin to dermatitis. Friction may also play a role, though this is likely a predisposing or exacerbating rather than dominant factor. Fecal enzymes including proteases and lipases have direct irritant action on the skin and their effects are increased by an alkaline environment. Finally, microorganisms, particularly candida, but also staphylococcus, peptostreptococcus, bacteroides, herpes virus, and dermatophytes can worsen irritant diaper dermatitis (Prasad et al., 2003; Wolf et al., 2000).

Other causes of dermatitis in the diaper region include seborrheic dermatitis, psoriasis, atopic dermatitis, congenital syphilis, acrodermatitis enteropathica (zinc deficiency), scabies, child abuse and miliaria. Finally, dermatitis of the diaper area may also be allergic contact dermatitis. Allergens to consider in this setting include sorbitansesquioleate, fragrances (mix I and balsam of peru), disperse dye, cyclohexlthiopthalimide, mercaptobenzothiazole, iodopropylcarbamate, bronopol and *p*-*tertiary*-butyl-phenolformaldehyde (Smith & Jacob, 2009).

Prevention and management of irritant diaper dermatitis revolves around keeping the occluded skin dry and limiting the amount of time that the skin is exposed to urine and feces. Removing diapers is one of the oldest and most effective measures in preventing and treating this condition. Frequent diaper changes are most helpful if done immediately after urination and bowel movements (every hour in neonates and every 3-4 hours in infants). Some experts recommend washing the area with mild soap, while others suggest that rinsing the area in lukewarm water is sufficient. New technology has allowed diapers to be much more absorbent and effective in keeping skin dry and with a normal pH. In terms of topical treatments, low potency steroids can be effective for inflamed skin. However, even if these are applied for a short time to acute disease, a waterproof emollient should be placed over them as a barrier to protect the skin. Ideally, emollients should be reapplied after every diaper change. Emollients effective in this setting are usually made of a large quantity of fine powder, such as zinc oxide, suspended in a greasy vehicle. For those eruptions which are superinfected with candida, topical antifungals may also be required (Wolf et al., 2000).

#### **3.1.2 Perianal dermatitis**

An entity that is distinct from diaper dermatitis is perianal dermatitis. Fecal components including fecal lipase and bile acids can cause degradation of the skin barrier perianally, leading to an erythematous irritant dermatitis limited to perianal skin (Ruselet-van Embden et al., 2004). There are several less common diagnoses that are thought to be related to irritant perianal dermatitis and some believe that these exist on a spectrum of one disease. These entities include granuloma gluteale infantum, pseudoverrucous papules and Jacquet's erosive dermatitis.

Granuloma gluteale infantum is thought to be multifactorial and related to occlusion, powder, topical halogenated steroids, *Candida* infection, urine and feces. It classically appears as oval, red-purple granulomatous nodules at sites of occlusion (Robson et al., 2006). This condition will improve with removal of inciting agents (Al-Faraidy & Al-Natour, 2010). Pseudoverrucous papules and nodules is a less common condition and was first reported in association with urostomy sites but may also be seen in children in a perianal distribution. Lesions are shiny, smooth, red, moist, flat-topped and round and may be

Contact Dermatitis in Children 135

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

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

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

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

the small amount that is present in foods and tap water (Hsu et al., 2010).

watch, glasses and the ball point pen that he chewed (Grimm, 1971).

**3.2.1 Metals** 

Nickel

al., 2010).

Cobalt

Potassium dichromate

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 antinflammatory drugs (Paradisi et al., 2009).
