Everyone itches. It is normal. Individuals can usually ignore the sensation, although adults are better at this than children. An itching child can be a real problem.

There are numerous causes of pruritus in children. The conditions that most commonly produce “rashy, itchy kids” are scabies, atopic dermatitis, papular urticaria, insect bites, eczematized molluscum contagiosum, and urticaria.

When establishing the cause of a pruritic eruption in a child, as in an adult, the first step is to identify the primary lesion. The pattern of involvement, the location of the eruptions, and any secondary lesions can also be of help. Frequently it can take more than one visit to establish the cause of the problem, much to the frustration of the patient and family.

Identifying scabies

Scabies is common, pruritic, and often difficult to diagnose. It was first identified in 1687, which makes it one of the first diseases with an identifiable agent—Sarcoptes scabiei var. hominis.

Scabies is easily transmitted by close skin-to-skin contact. In children it is usually spread by non-sexual contact within families and between playmates. If more than one family member develops a pruritic eruption, scabies is the most likely cause.

The classic presentation consists of small, symmetrical, pruritic, erythematous papules involving the hands (particularly the web spaces of the fingers), flexural aspects of wrists, anterior axillary folds, buttocks, and genitalia (Figure 1). Pruritic, excoriated, penile papules are almost always scabietic in origin. Diffuse excoriation and eczematization, sometimes with secondary pyoderma, can obscure the classic features of scabies. Nocturnal pruritus is an important diagnostic feature, especially when the common nonspecific anti-itch treatments have not been helpful. The classic burrow—a short, linear, and sometimes wavy lesion—is frequently absent.

Special forms of scabies

Scabies incognito

Given the ubiquitous use of topical corticosteroids, the signs and symptoms of scabies can be masked in this form of the disease. The lesions may not be typical in appearance or distribution and can be unusual.

Nodular scabies

There are some individuals who develop only a few pruritic lesions. These lesions can become firm, slightly brownish in color, and excoriated. The nodules are usually found on the lower abdomen, the buttocks, and the male genitalia. This form of scabies is more common in adults than in children.

Scabies in infants

The pattern of scabies in infants is often more widespread and eczematous than in children and adults. There can also be involvement of the face, scalp, and the tops and soles of the feet—areas that are rarely involved in adults. Lesions can be more vesicular and frequently become impetiginized. Often the youngest child in the family has the most extensive eruption. The axillary fold involvement may be prominent given the common practice of picking infants up underneath the arms (Figure 2).

Scabies in families with fastidious hygiene

Individuals with fastidious hygiene may have lesions that are sparse in number and less prevalent on the hands and wrists. As the lesions are few, the problem of itching is much less. The disease process can go undetected for a long period of time.

Scalp involvement

Infants and young children, along with the elderly and the immunocompromised, may have crusted lesions of the scalp, ears, and face. Frequently there is secondary infection from excoriation.

Vesiculobullous reaction

Bullous lesions are more frequent in infants and young children. This is true for a variety of dermatologic conditions. Staphylococcal pyoderma is an example. Possibly this is due to a weaker cellular adherence. The presence of vesiculobullous lesions in young children should not dissuade the physician from considering the diagnosis of scabies.

Norwegian scabies

This unusual form of scabies occurs primarily in individuals who are immunologically compromised with adult T-cell leukemia/lymphoma. The eruption presents as diffuse erythematous scaling process with severe crusting, especially of the hands and feet.

A high index of suspicion is the first step in the diagnosis of scabies. The presence of other itchy family members or close friends is also helpful. Nocturnal pruritus that develops relatively suddenly in a child who has otherwise had no skin problems can be suggestive. In infants, a characteristic but unusual sign of scabies is the rubbing together of the soles of the feet. There are usually erythematous papules to be seen.

The definitive diagnosis is made by microscopic identification of the mite, eggs, or feces. This is not always practical or easily done. Scrapings of burrows or papules are placed on a glass slide and examined microscopically under low power. Several lesions may have to be firmly scraped to get positive identification. From a practical point of view, clinical suspicion should overrule negative microscopy.

Identifying other conditions

Aside from scabies, the most common conditions to be considered when presented with an itching child are listed in the Table.

Atopic dermatitis or infantile eczema is a common genetically determined condition. Classically, the patient presents with facial lesions at 4 to 6 months of age. There may be ill-defined patchy eczema on the trunk and extremities. In later childhood, the pattern is more flexural, involving antecubital and popliteal fossae, and flexural aspects of the wrists (Figure 3). Pruritus is always worse at night. A family history of cutaneous atopy, asthma, and hay fever is common. Repeated scratching can produce persistent scratch papules or prurigo papules with or without secondary superficial crusted pyoderma.

Papular urticaria is a term given to episodic, symmetrically distributed, erythematous papules that are caused by the bites of insects such as mosquitoes, fleas, and bed bugs. This condition may be more common in atopic children. Pruritus can be significant, especially at night (but itching from any cause is frequently worse at night). The repeated scratching can produce a chronic problem of thickened cutaneous nodules (Figure 4). Asian skin seems more prone to this nodular reaction.

Insect bites from fleas and mosquitoes are usually transitory in nature, bright red, with a central punctum. Covered areas are frequently involved. The lesions can be localized, a phenomenon referred to as the breakfast-lunch-supper pattern (Figure 5). For most common insect bites, the morphology of the bite gives no clue to the identity of the biting insect. Not all individuals are the right “flavor” to be bitten, and some do not develop significant local reactions when bitten, so it is not uncommon to see only one family member having a problem. Parents will often discount the diagnosis because of this.

Molluscum contagiosum is a common, benign disease of the skin and mucous membranes that is caused by a specific poxvirus. It might not seem that molluscum contagiosum would be part of the differential diagnosis of scabies. However, molluscum lesions that become eczematized and inflamed can be difficult to identify. In children, molluscum contagiosum is not usually transmitted sexually. The classic lesion is a skin-colored papule of 1 mm to 3 mm with central umbilication (Figure 6). The lesions can be haphazardly scattered over the skin, although in young children they often tend to be on the lateral aspects of the trunk extending into the axillae and the inner surfaces of the upper arms. The diaper area extending to the buttocks and thighs is also commonly involved. There may be a few lesions or hundreds. What makes the diagnosis difficult at times is that an eczematous reaction may develop around the lesions so that the excoriation and erythema hide the small molluscum lesions. At first glance, the eczematous reaction is noted and the molluscum lesions are missed.

Urticaria is less common in children than in adults and can be difficult to recognize. Rather than noticing a child’s transient urticarial wheals, parents may notice only the excoriation and scratching, and hear the complaints of itching (Figure 7). Often scratching of pruritic skin can induce secondary dermatographism. This presents with linear erythematous wheals that are markedly pruritic. Atopic individuals seem to be more prone to dermatographism.

Managing scabies

Once the diagnosis of scabies is established, treatment can be initiated in two directions: specific antiscabietic therapy and nonspecific management of the secondary problems of itching, eczematization, and possibly pyoderma.

The principles of specific treatment include the choice of an agent based on efficacy and potential toxicity. This can be a real problem in very young infants. Agents are traditionally applied thinly from the neck down to all areas, whether they are involved or not. There may be a need to include the scalp, face, and ears depending on the clinical involvement. The medication is left on, usually for 8 to 10 hours, and bathed off. Those articles that have been in close contact with the patient’s skin—bedclothes, linens, and underwear—are washed with soap and water and then dried using the hot dry cycle. There is no need to be aggressive in cleaning external clothing, mattresses, or other surfaces. All family members and other individuals in close contact with the patient, whether they are symptomatic or not, should be treated once. It is usual for the patient to receive a second treatment 5 to 7 days later.

Specific antiscabietic agents

Currently, permethrin 5% cream or lotion (Kwellada-P lotion, Kwellada-P cream rinse, Nix cream) are the agents of choice. Permethrin is a pyrethroid, a synthetic insecticidal agent. Do not confuse Kwellada-P lotion with Kwellada lotion, which was the common lindane product used for many years.

The safety profile of topical permethrin is good, although it is not recommended for use in infants younger than 2 months. During early infancy, as during pregnancy and lactation, topical permethrin is used when the expected benefits outweigh the potential risks. The preparation is usually well tolerated. It can occasionally produce a burning irritation. Permethrin cream rinse is used only for scalp lesions if they are present. Primarily it is used for treating pediculosis capitis.

Topical lindane 1% lotion has been used for many years. It is as effective as permethrin. It was once widely used under the name Kwellada lotion but its use has declined dramatically in recent years because of concerns about systemic toxicity (10% of the lindane applied to the skin can be absorbed). Central nervous system toxicity has been reported, primarily as a result of incorrect application, overuse, and lack of patient compliance. It is not recommended for infants and young children.

Topical 6% sulfur ointment is an old-fashioned treatment used rarely now, as it is minimally effective, messy, and odiferous. Its safety in infants and young children has not been established. It is applied for 3 consecutive nights.

Crotamiton cream (Eurax) is not a very effective antiscabietic agent, but it is an effective topical antipruritic. The cream was used more extensively in the past when fewer effective antiscabietic preparations were available. It is applied twice daily for 5 to 7 days.

Nonspecific management of scabies

While specific antiscabies therapy is mandatory, it does not necessarily give rapid relief from the generalized eczematous and irritated reactions. The relief of pruritus and secondary eczema may take 2 to 4 weeks. Frequently, the persistence of pruritus produces so much patient concern that it leads to overuse of the irritating topical antiscabietic agents, which themselves can cause contact dermatitis.

The persistence of scabies for any period of time usually invokes a nonspecific papular eczema, which can involve areas other than the classic scabietic locations. In fact, the actual number of mites in the skin is usually small compared with the widespread extent of the eruption. This “scabietic eczema” can be a persistent problem long after the scabies mite has been eradicated. The itch-scratch cycle can be self-perpetuating, causing great patient discomfort and anxiety.

The following general instructions for managing irritated eczematous skin should be given to families:

• Take short tepid baths or showers with minimal amounts of soap.
• Avoid hot tubs and whirlpool baths. 
• Wear soft fabrics and avoid irritating wool and synthetics.
• Avoid overdressing with bedclothes to prevent overheating at night.
• Use topical antipruritics such as bland emollients and antipruritic lotions. These include pramoxine/menthol/camphor lotions (PrameGel, Sarna-P).
• Use topical corticosteroids. These are valuable agents for the secondary irritation reaction. Start topical corticosteroids immediately following the first antiscabietic treatment, applying two to three times daily. For infants and young children with a modest problem, hydrocortisone 1% cream is usually adequate. For more severe and persistent reactions, medium-strength topical corticosteroids such as triamcinolone 0.1% cream or betamethasone 0.05% cream can be used, provided the duration of use does not exceed 1 to 3 weeks. Antipruritics such as menthol (0.25% to 0.5%) or camphor (0.25% to 0.5%) can be added to the corticosteroid base.
• Use oral antipruritics. These can be helpful, especially for nocturnal pruritus. Hydroxyzine and diphenhydramine are commonly used.

If treatment seems to have failed after 2 to 3 weeks, the following question should be asked:

• Was the diagnosis correct? 
• Has there been adequate patient compliance? 
• Has the patient been overtreating the skin? 
• Has there been re-exposure to scabies? 
• Has the patient developed a post-scabietic eczema that has become self-perpetuating?

As with all medical conditions, the patient and family will do best if they are well informed. The diagnosis of scabies, or even the suggestion of scabies, can produce disbelief and an emotional reaction based on the erroneous understanding that improper hygiene is the cause. Management can be a challenge, especially when the problem does not clear quickly.

Managing other conditions

Atopic dermatitis is too large a subject to discuss here in detail. However, a review of the basic principles can be useful. The factors that make atopic skin itch include the following:

• Inherent lower cutaneous itch threshold.
• Dry skin.
• Increased incidence of contact with irritant.
• Sweating and overheating.
• Emotional stress.
• Cutaneous superinfection, not always with classic pyoderma.
• Allergic contact dermatitis, especially in response to nickel.

Efforts to minimize the above factors are as important to the dermatologic management of a child with atopic eczema as are the specific therapeutic agents prescribed. At times, the diverse ethnicity of our patient population and the resulting language barriers can make it difficult to obtain adequate treatment compliance. Even without language barriers, it is hard for some parents to accept that there is no simple and single treatment to assure speedy clinical success.

The general nonspecific skin care practices outlined for scabies are also good for nonscabietic conditions. An important addition is the regular and thorough lubrication of atopic skin. Applying bland emollients to dampened (not dry) skin is required. Emollients will vary depending on patient comfort and preference and can range from petroleum jelly to lighter, less greasy, unscented products. Antipruritic therapy includes oral agents such as hydroxyzine and diphenhydramine. Topical corticosteroids are the mainstay of topical treatment. The choice of specific agents is similar to that outlined for the treatment of scabies. The objective should be to use the least potent product possible because of the potential long-term cutaneous side effects. It is prudent not to give unsupervised refills of topical corticosteroids. Children’s skin is more likely than adult skin to develop cutaneous atrophy.

A significant advance in topical therapy for atopic dermatitis has been the introduction of topical immunomodulators: tacrolimus (0.03% or 0.1%) ointment (Protopic) and pimecrolimus 1% cream (Elidel).[1,2] These agents are indicated for non-immunocompromised patients of 2 years or older for the short-term. They can also be used intermittently for the long-term and for mild and moderate disease. They are especially valuable when the conventional therapies are inadequate or pose risks. They are not to be used when there is clinical evidence of viral infection. The most common adverse reaction is a sensation of burning or warmth, which is usually transitory. The expense of the preparations makes their use most feasible for relatively localized disease.

Nonspecific management of other conditions

Papular urticaria usually responds readily to treatment, providing the insects stop biting. General measures should be used to keep the skin cool and free of irritation. Topical corticosteroids, essentially the same ones that are used for treating an eczematous reaction to scabies, are satisfactory. Oral antipruritics can be helpful. Patients and family members benefit from reassurance regarding the nature of the process.

Insect bites can be difficult to treat because it is often impossible to identify the biting insect, making only general measures of environmental management possible. Attention to the possibility of infested pets is needed. Remember that adult fleas and eggs can remain viable for months in a vacant house. Insect repellents such as diethyltolumanide (DEET) are the preferred agents, although not always totally efficacious. (Encephalopathy due to extensive and repeated use of diethyltoluamide has been reported in children.) Permethrin spray of clothing can also be helpful. There are numerous common products, such as thiamine, that have their proponents. Unfortunately, there is no scientific support for their use.

Molluscum contagiosum is said to be a self-limiting infection, although in my experience this seldom seems to be the case. The treatment depends on the site of infection, and on the patient’s age and ability to cooperate. Isolated sparse lesions can be removed physically by extraction, curettage, or cryotherapy. Multiple lesions, especially in young children, can be successfully managed with the use of the topical blistering agent cantharidin solution (Cantharone). This treatment produces vesiculation at the applied site and usually heals without much incident. Caution needs to be used when treating facial lesions and also when individuals are darker skinned. Repeat treatment sessions are frequently required. Look also for affected family members as a source of reinfection.

In patients who do not respond to the usual treatments, there have been encouraging reports of the use of the topical immunoresponse modulator, imiquimod cream (Aldara).[3] This cream has the advantage of being well tolerated and easy to apply (three times weekly). The disadvantage is the cost of the medication. Nevertheless, in children or those with widespread or awkwardly situated lesions, such as on the face, it can be a very satisfactory choice. The treatment course is usually 8 to 12 weeks. Topical keratolytic agents, such as tretinoin 0.025% or 0.05% cream, can also be successful at times, presumably because of the peeling effect they produce.

Conclusions

The management of an itching child is not easy. The age of the patient often does not permit motivation or self-discipline to be part of the therapeutic program. It is not always easy to make a rapid diagnosis, and parent expectations concerning the length of treatment required can be unrealistic. In spite of the best efforts and a high index of suspicion, scabies can be missed. Perhaps the best approach is to treat anything that seems remotely like scabies as if it were scabies. The downside is minimal. The upside is that you and the patient may be happily surprised with the results.

Competing interests

None declared.

Table. Common conditions that mimic scabies.

Dr Dodd is a dermatologist in private practice in Vancouver, BC.