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Atopic Dermatitis

Michael A. Davis, MD

Epidemiology. The incidence is 7/1,000 but the prevalence in the pediatric age group approaches 5%, maybe even as high as 10% in children between the ages of five and 10 years. Ninety five percent of all patients will have their first outbreak by age five. It is extremely unusual for patients to have their first manifestation after 10 years of age, which is important when you consider a number of other dermatitic processes that may present with skin lesions that look very much like atopic dermatitis. After the age of 10, think of other things in your differential diagnosis. And although the inheritance isn't clear, it is probably multifactorial, with inheritance playing a role. If you look at families with atopic history, one-third of all the children in these families will develop atopic dermatitis. About one-third of atopic children will have respiratory symptoms, one-half of these children will continue to have respiratory symptoms into adult life. If you have a patient that has both a moderately severe atopic dermatitis as well as asthma, their risk of having atopic dermatitis into adult life is significant.

A number of immunologic factors as well as inflammatory mediators are felt to play a role in the pathogenesis of the disease. Humoral immunity is felt to play a role based upon some clinical as well as immunologic findings. There is an increase in immediate heightened sensitivity to a number of environmental antigens. There clearly is an increase in serum IgE levels in patients with atopic dermatitis. It tends to be relatively moderate and there is clearly an overlap between the normal population and those with an atopic diathesis.

There are a number of immunodeficiency syndromes including Wiskott-Aldrich syndrome, Ataxia-telangiectasia, hyper-IgE, and hypereosinophilic syndrome in children which have been associated in some cases with particularly severe presentation of the atopic diathesis.

Triggering factors may be environmental antigens, such as foods; a number of allergens; infectious agents, bacteria, fungi, viral agents.. Inflammatory mediators are released by skin endothelial cells, and they produce the pruritus. Patients scratch and they create the itch-scratch cycle. The more they scratch, the more inflammatory mediators they release. The more they itch, the more they scratch and if you are going to treat these patients successfully, you need to interrupt this itch-scratch cycle.

Clinical presentation.

In acute dermatitic processes, one sees erythema, vesicles, crusting. You may see secondary infection. If the patient has a flare of their atopic dermatitis, you will see acute changes in the skin. Patients with chronic changes will have lichenification or accentuation of the normal skin margins with thickening of the epidermis. These patients will have excoriation and pigmentary change. They will have scale. These changes suggest a process which has been ongoing for days if not weeks or months. Again, you can see this in association with the acute changes when the patient has acute flares of their atopic disease.

Age related patterns will help you make the diagnosis. In infancy, all areas of the skin fair game for presentation of the skin lesions with the exception of protected areas. The diaper area is invariably spared until the patients are toilet-trained. Then you start to see lesions in the diaper area and this is a reliable finding. Widespread disease affects the head and neck, the extremities. The trunk may be relatively spared because it is a relatively protected site. This child has both some acute changes of erythema and scaling and crusting. This child has some chronic changes and lichenification. In fact, in this age group, it is probably more common to see involvement over the extensor surfaces of the arms and legs because the flexural creases are actually relatively spared sites. So in this age group, you expect to see exactly the opposite of what you see in a slightly older child. The scalp is a common area of involvement. Certainly, in younger infancy, you see seborrhea, but if it is seborrheic dermatitis, it doesn't itch and if it itches you need to consider the possibility of atopic dermatitis.

In a slightly older age group, in the childhood age groups, after infancy when you get into older toddlers through school age you tend to see flexural involvement. It doesn't have to be restricted only to the flexural creases and on occasion it may be widely disseminated; the diaper area in these children ,who are usually toilet-trained, can certainly be involved. The dorsal flexural surfaces can be involved and again you see both complaints of an acute and chronic dermatitis here. Lichenification is symmetric crusting pruritus is commonly involved and this area can be thought of as being one of the flexural creases that you typically see in school-aged children.

In teenagers and adults, flexures tend to be involved preferentially. Probably three-quarters, maybe as many as 85-90%, of children will have their disease go into remission in the late school-aged years or adolescent years. But certainly there are some patients who have persistent disease. There are many patients who will go into remission only to have recurrence of their lesions when they get involved in occupations or hobbies that expose them to irritants.

Hand dermatitis with chronic dermatitis, thickening of the skin, lichenification on the extensor surfaces of the fingers, is a typical finding in adolescents and adults. Involvement of the sides of the digits of both the hands and feet, occasionally the palms and the soles with deep-seated vesicles which are incredibly pruritic. They may rupture at the surface leaving a crust at the surface.

Prurigo nodularis. There are some patients who rather than rubbing and scratching, are pickers. And these are picker's nodules. These patients develop thickening of the skin. If you biopsy the skin, you see the epidermis may be 10-15 times its normal thickness. Inflammation is present, suggesting chronic change. Some of those patients create prurigo nodularis. This is certainly an associated finding, and I think, in most children when you see prurigo nodularis you are dealing with an atopic.

Hyperlineary of the palms and soles is a relatively common finding associated with atopic dermatitis. It may also be seen in association with ichthyosis. Thickening of the skin as well of the palms and soles and ichthyosis vulgarisis common in, patients with atopic dermatitis. Discrete papules that often have this predilection for involvement around hair follicles are common.. Nummular eczema is characterized by vesiculation, crusting, erythema, intense pruritus, typically in teenage girls, typically on the proximal extremities. Not necessarily associated with other typical findings of atopic dermatitis.This as a manifestation of atopic disease.

Ichthyosis vulgaris. This can certainly occur again as an independent entity. It usually does not present until after six months of age, so it should not be confused with some of the other ichthyoses that can present with devastating effect in the newborn period. Typically on the distal extremities. The most common sites would be just the lower extremities, the shins. These patients may have hyperlineary of the palms and soles. They may have keratosis pilaris. These thorny little sand-papery-like papules in the back of the upper arms, cheeks and thighs which again also are associated with atopic dermatitis.. This is inherited. It is autosomal dominant. If you have any question about, you can ask their parents to roll up their pants and roll up their sleeves and see the same thing. You have a 50-50 shot of having it with the parent who brings the kid to see you.

Keratosis pilaris. It is also seen typically in association with atopics. You see the sand-papery papules on the arms and legs and people present with this a couple of ways. You may see it as a concomitant finding in atopics. You may see it in the summer when these patients present with erythema of the cheeks. You may also see it during the winter when their skin tends to be dry, when their eczema tends to flare up and when the sand-papery papules on the arms and legs become more prominent.

Pityriasis alba. Pityriasis alba, which translates directly into English as "white spot disease", it is a manifestation of atopic dermatitis. If you look carefully, you'll see that most of them have some fine scale. Many of them will have some finer or more subtle erythema and they get postinflammatory hyperpigmentation most typically on the extremities. It can involve the face. If you ask careful questions, you will often be able to make the diagnosis of atopic dermatitis.

With the intense inflammation, you can see postinflammatory pigmentary changes in association with atopic dermatitis and the intense inflammation, hypo- and hyperpigmentation can occur in the same patient.

In patients who present with a chronic dermatitic process, you want to moisten the skin. You want to use products which have oil and petrolatum in them.

If you have a patient with an acute process and you give them a water-based product, it may sting and burn. So, it is important that you consider the vehicle. If you have a patient that develops some sort of an adverse reaction to the topical preparation, in may in fact not be the medicated product at all. It may be one of the components of the vehicle. So you need to look carefully at the "inert" ingredients.

Single versus combination products. Only agents which have a single medicated product in them should be used.If you want to use a number of different agents, if you give them separately, as a general rule, they are much less expensive. You can also control the time for which they are applied. If you have a combination product, you buy into everything being put on at the same time. If you have a combination product and a patient has an adverse reaction, develops contact dermatitis, again you don't know which medicated product is producing the problem and you're stuck with having to discontinue the product. Cost considerations. I suggest that you go to your local pharmacy and see what they have. There may be certain topical corticosteroids which they have available in a large quantity, which they have available in an ointment based product, which is what I generally use in atopic patients. I think it is reasonable to look and see what is available and pick out an agent or two in the low potency range and the middle potency range that you become very comfortable with.

Many physicians don't realize how much of a topical agent it takes to cover the skin surface, hands, face, anal-genital area. One application requires 2 gm. To cover the entire skin surface once, takes about 30 gm of the product. So give the patient the amount of product that you really think they need.

Lubricants. As a general rule, I like safe, simple, inexpensive bland lubricants. In young children, this means that you can send them home with a pound jar of Vaseline. You can use those safe products like Vaseline. You can send them to the store and they can buy mineral oil inexpensively. By in large, ointment-based products have few preservatives. They require few stabilizers. When you get into the cream-based products, they tend to be more irritating. They tend to be less occlusive and they tend to have more stabilizers, preservatives and other products in the vehicle which can get you into trouble. Same thing is true for all these lubricants.

This is just an abbreviated list of the topical steroids which are available. Because of the large number of products that are out there, again, I suggest that you go to your local pharmacy and see what your pharmacist gets. They may get a number of products. Pick a couple of the products and a couple of potency ratings in an ointment-based preparation.

The diaper area stays clear in infants and toddlers because it is wet all the time and it is protected. It is protected from outside irritants. It is protected from hands which scratch and excoriate the skin. Clothes should be kept on. They should not be allowed to just run around in their diapers. Protective clothing. Long underwear at night after they apply the lubricants. It tends to keep their skin, at least the areas that are covered, under relatively good control. The older the child, the more likely they are to have the capability of removing their clothes and doing a lot of damage. Emollients will get you 50% of the way there. Simple, plain emollients and low to medium potency topical steroids with an ointment-based vehicle.

Keeping your clothes on protects you from upholstery. Protects you from carpeting. Protects you from nummular irritants. Using common sense when it comes to using cotton or cotton blends. Anything that makes you itch. Anything that makes the doctor itch is going to make the patient itch. My recommendation in terms of water exposure is for bathing to be done regularly. Once a day would be reasonable in the summer, maybe every other day in the winter. Swimming. There are some kids who do much better when they are in the pool. They do much better when they are at the beach and I encourage these kids to get in as long as they take the lubricant to the pool side. Antihistamines. There is no appropriate use of topical antihistamines. When you use it on inflamed skin, topical antihistamines tend to be potent sensitizers. In those children who develop urticaria in association perhaps with food or other antigens, there may be a more systemic role as well for antihistamines.

Complications of atopic disease. Secondary bacterial infection, viral infections, a number of chronic infections can be an issue in atopics. Impetiginitis atopic disease can develop dissemination and disseminated disease. When you see a child who presents with an acute flare, a fever, and extremely discrete monotonous vesicular crusted lesions, you need to consider the possibility of a primary herpes simplex infection. Probably after impetiginization of the atopic, disseminated primary herpes simplex should be your next consideration in a child who presents with an acute flare of disease and a fever. These lesions can become widespread, they can occasionally disseminate viscerally. Molluscum.. Atopics tend to have difficulty managing this and they have chronic and persistent disease, much longer than you are used to seeing in the normal non-atopic host. Chronic fungal infections also can be an issue. Many of these infections can present on a superimposed severe flare of the atopic disease which can also make it difficult to recognize them.

Melanoma is a disease of young adults; it is a disease of people in their prime, you need to get kids to protect themselves from sun. There is a good deal of mounting evidence to suggest that sun plays a major role.

Two percent of all cancer deaths are caused by melanoma. Three percent of teens by neoplasms. It is key that we recognize that we need to protect these kids from sun and it is key that we look for these lesions and identify them when they are thin. A thin melanoma is under 1 mm. An intermediate melanoma is 1 to 3 mm; over 3 mm we are talking about major morbidity and significant mortality. Look for changes in color especially if these changes occur in an irregular asymmetric way. Look for changes in size. Sudden growth of a mole can certainly be, in most cases, benign, but it may be the first marker of something going in the wrong direction. Lesions which rise in height. Certainly if it occurs again in an asymmetric way, a portion of the mole is becoming elevated when the rest of it is remaining uniformly level with the skin surface. Changes in shape. Changes in texture, again especially if they occur in a non-uniform way. Changes in sensation. Moles can become irritated and develop inflammation, but melanomas typically develop an inflammatory infiltrate, and the patient may complain of itching and burning. New moles, especially if the new moles don't look like the old moles are a concern..

Epidemiology and Pathogenesis

Atopic dermatitis has an incidence of 7/1,000 and a prevalence of 3-5% of children.

95% of affected children will have symptoms by age 5.

The inheritance pattern is multifactorial.

Pathogenesis is related to immunologic factors, histamine and vasoactive mediators.

Triggering factors

Foods, environmental allergens, and bacteria.

IgE

Individual with genetic predisposition

Inflammatory mediators: Histamine, prostaglandins, neuropeptides

Inflammation

Pruritus

Acute dermatitis

Chronic dermatitis

External factors including foods, bacteria, and environmental allergens trigger the release of cutaneous inflammatory factors, resulting in pruritus and inflammation of the skin of susceptible individuals. Secondary manipulation of the skin [i.e. rubbing and excoriation) produces many of the symptoms of acute and chronic dermatitis. Dermatitic changes in the skin result in further pruritus, thus potentiating an escalating cycle of increasing clinical findings, particularly during flare periods.

Adolescence and Adulthood. In adults, the lesions are usually restricted to the flexural creases. However, in some patients, involvement of the palms and soles may become particularly prominent,

Complications of Atopic Dermatitis

Secondary bacterial infection

Viral infections (herpes simplex, molluscum)

Chronic fungal infection

Differential Diagnosis

1. Seborrheic dermatitis

2. Irritant dermatitis

3. Papular acrodermatitis

4. Psoriasis

5. Fungal infection

6. Scabies

Treatment of Atopic Dermatitis

1. Lubricants

2. Brief, regular bathing. Use of mild oaps

3. Topical steroid

4. Environmental control measures

5. Antibacterials

6. Foods?

7. Allergy Rx?

References

Hanifin JM: Basic and clinical aspects of atopic dermatitis: a review. Ann Allergy 52:368-375, 1984.

Hanifin JM, Lobitz WC: New concepts of atopic dermatitis. Arch Dermatol, 113:663, 1977.

Krafchik B: Eczematous dermatitis, in Schachner LA, Hansen RC:

Pediatric Dermatology, Churchill-Livingstone, 1988, pp. 695-724.

Leung D, Rhodes R, Geha RS: Atopic dermatitis, in Fitzpatrick TB, Eisen ZA, Wolff K, Freedburg IM, Austen KF (eds}: Dermatology in General Medicine, McGraw-Hill, New York, 1987, pp. 13851408.