Eczema:A particular type of inflammatory reaction of the skin in which there are typically vesicles (tiny blister-like raised areas) in the first stage followed by erythema (reddening), edema (swelling), papules (bumps), and crusting of the skin followed, finally, by lichenification (thickening) and scaling of the skin. Eczema characteristically causes itching and burning of the skin.

 

 

Eczema, which is also called atopic dermatitis, is a very common skin problem. It may start in infancy, later in childhood, or in adulthood. Once it gets underway, it tends not to go quickly away.

There are numerous types of eczema, including:

• Atopic dermatitis — a chronic skin disease characterized by itchy, inflamed skin
• Contact eczema — a localized reaction that includes redness, itching, and burning where the skin has come into contact with an allergen (an allergy-causing substance) or with an irritant such as an acid, a cleaning agent, or other chemical
• Allergic contact eczema — a red, itchy, weepy reaction where the skin has come into contact with a substance that the immune system recognizes as foreign, such as poison ivy or certain preservatives in creams and lotions
• Seborrheic eczema — a form of skin inflammation of unknown cause that presents as yellowish, oily, scaly patches of skin on the scalp, face, and occasionally other parts of the

body

• Nummular eczema — coin-shaped patches of irritated skin—most commonly on the arms, back, buttocks, and lower legs—that may be crusted, scaling, and extremely itchy
• Neurodermatitis — scaly patches of skin on the head, lower legs, wrists, or forearms caused by a localized itch (such as an insect bite) that becomes intensely irritated when scratched
• Stasis dermatitis — a skin irritation on the lower legs, generally related to circulatory problems
• Dyshidrotic eczema — irritation of the skin on the palms of hands and soles of the feet characterized by clear, deep blisters that itch and burn

 

Eczema herpeticum. Widespread punched-out lesions on a child with atopic dermatitis and superimposed herpes simplex infection.

 

 

Nummular eczema: Coin-shaped patches of irritated skin-most common on the arms, back, buttocks, and lower legs that may be crusted, scaling, and extremely itchy.

The word "nummular" is taken from the Latin "nummus," a small coin.

 

 

 

Eczema is a skin condition caused by inflammation. Atopic dermatitis is the most common of the many types of eczema. While the word "dermatitis" means inflammation of the skin, "atopic" refers to an allergic tendency, which is often inherited. These eczema sufferers have a higher risk of developing other allergic conditions (like asthma or hay fever).

Eczema is a chronic problem for many people. It is most common among infants, many of whom outgrow it before school age.

 

 

 

Xerosis: Abnormal dryness of the skin (xeroderma), of the conjunctiva of the eye (xerophthalmia), or of the mucous membranes such as dry mouth (xerostomia).

The word "xerosis" literally means "dry condition." It was compounded from the Greek roots "xero-" (dry) and "-osis" (condition).

 

 

 

Allergic contact dermatitis: A red, itchy, weepy reaction where the skin has come into contact with a substance that the immune system recognizes as foreign, such as poison ivy, poison oak or poison sumac or certain preservatives in creams and lotions. This type of reaction reflects a specific sensitivity or allergy to a specific substance. Also called allergic contact eczema.

 

 

 

Allergic contact dermatitis (reaction to temporary tattoo). Contact allergy to temporary tattoos has become an increasingly common phenomenon. In most cases, the tattoo material does not contain pure henna, but is a mixture of brown henna with paraphenylenediamine (PPD) called black henna. The patient is allergic to PPD in the tattoo. In fact, the concentration of PPD in black henna is higher than that seen in commercial hair dyes. After resolution of the eczematous skin eruption, postinflammatory hyperpigmentation may persist for a considerable period of time.

 

 

 

Allergic contact dermatitis (reaction to temporary tattoo). Contact allergy to temporary tattoos has become an increasingly common phenomenon. In most cases, the tattoo material does not contain pure henna, but is a mixture of brown henna with paraphenylenediamine (PPD) called black henna. The patient is allergic to PPD in the tatto. In fact, the concentration of PPD in black henna is higher than that seen in commercial hair dyes. After resolution of the eczematous skin eruption, postinflammatory hyperpigmentation may persist for a considerable period of time.

 

 

 

Nickel contact dermatitis. The development of an itchy eczematous eruption near the umbilicus is virtually pathognomonic for contact dermatitis to nickel. The source is the small metal snap in the blue jeans or the metal belt buckle. The simultaneous occurrence of an id reaction, sometimes with small lichenoid papules on the elbows and knees, is very common. Lesions can be treated effectively with topical corticosteroids, but the only cure results from strict avoidance of nickel. This is easier said than done. Parents must buy jeans without snaps or sew in a small piece of fabric to protect the underlying skin. Families should be reminded that wearing jeans with a metal snap for just several hours out of the month would reactivate the entire process. Children with contact dermatitis to nickel should also avoid metal jewelry and should be advised against ear piercing.

 

 

 

Nickel contact dermatitis. Allergy to nickel is one of the most common causes of contact dermatitis in children. Infants may present with skin lesions corresponding to the location of snaps on their pajamas or other garments. Older children may show reactions to watches, chains, belt buckles, or earrings.

 

 

 

Cercarial dermatitis: swimmer's itch. Erythematous papules on the exposed areas of a swimmer. Cercarial dermatitis (swimmer's itch) is a skin rash caused by an allergic reaction to an infection with certain microscopic parasites of birds and animals. The parasites are released from infected snails who swim in fresh and salt water. Symptoms of cercarial dermatitis or swimmer's itch include burning, tingling, and itching of the infected skin. Small reddish pimples appear within 12 hours of exposure. The pimples may develop into small blisters. Itching may last up to a week or more but will gradually go away. Cercarial dermatitis (swimmer's itch) is not contagious. Treatment includes corticosteroid creams, anti-itch or Calamine lotions, or other creams.

 

 

 

Drug eruptions (dermatitis medicamentosa). Diagnosing drug eruptions has become a common experience to practitioners in all branches of modern medicine. The profusion of drugs now available, the continuous influx of new drugs, and the capability of drugs to cause actions different from or in addition to their pharmacologically desirable actions make adverse cutaneous reactions an inevitable fact of modern medical practice. The kinds of cutaneous reactions are varied. Exanthems (erythematous, morbilliform or maculopapular), urticaria, fixed drug eruptions, and erythema multiforme are the most common. Figure 18-1 is an urticarial reaction from Augmentin and Fig. 18-2 shows a morbilliform eruption from ampicillin. Constitutional symptoms of low-grade fever and malaise may be associated with such drug eruptions. Morbilliform eruptions from ampicillin are more frequently seen in children with infectious mononucleosis.

 

 

 

Drug eruptions (dermatitis medicamentosa). Drug eruptions may mimic nearly the entire range of dermatoses of other causes. One of the commonest forms is the exanthematic, whose lesions are usually erythematous and edematous. Common causes of drug eruptions include ampicillin, cephalosporins, semisynthetic penicillins, and barbiturates. We have just illustrated cases that were morbilliform. Illustrated here are cases clinically resembling erythema multiforme.

 

 

 

 

Lichen striatus. This is a common and benign self-limited childhood dermatosis that is easily diagnosed from its classic appearance. Onset is usually between the ages of 3 and 10 years, and it is rare in young infants, adolescents, and adults. The lesions consist of pink, flesh-colored, or slightly hypopigmented flat-topped papules that evolve in a linear array following lines of Blaschko. The linear course of the papules may eventually traverse the major part of an extremity. The area of involvement is often noted to become wider as it advances and may even include the nails.

 

 

 

Lichen striatus. This is a common and benign self-limited childhood dermatosis that is easily diagnosed from its classic appearance. Onset is usually between the ages of 3 and 10 years, and it is rare in young infants, adolescents, and adults. The lesions consist of pink, flesh-colored, or slightly hypopigmented flat-topped papules that evolve in a linear array following lines of Blaschko. The linear course of the papules may eventually traverse the major part of an extremity. The area of involvement is often noted to become wider as it advances and may even include the nails.

 

 

 

Palmoplantar pustulosis, also referred to as pustular psoriasis of the palms of the hands. The palms are red with white or yellow pustules. Palmoplantar pustulosis is a type of recurring psoriasis characterized by the appearance of pus-filled pimples and sores in clusters.

 

 

 

Palmoplantar pustulosis, also referred to as pustular psoriasis of the soles of the feet. The soles of the feet are red with white or yellow pustules. Palmoplantar pustulosis is a type of recurring psoriasis characterized by the appearance of pus-filled pimples and sores in clusters.

 

 

 

Photoallergic reaction: An allergic reaction caused by drugs in which ultraviolet exposure changes the structure of the drug so that it is seen by the body's immune system as an invader. The allergic response causes inflammation of the skin in the sun-exposed areas. These usually resemble eczema and are generally long-lasting. Many drugs in this family are topical drugs. Individuals with photoallergic reactions may initially complain of itching (pruritus). This is then followed by redness and possibly swelling and eruption of the involved area. Common photoallergic drugs include some sunscreens, antimicrobials, painkillers, chemotherapy drugs, and fragrances.

 

 

 

Phototoxic dermatitides. In phototoxic reactivity, no immunologic mechanism is involved, and the patient reacts as anyone would to a primary irritant. Phototoxic drugs and chemicals include some dyes, coal tar derivatives, and psoralens. Drugs that may cause a phototoxic reaction include the sulfonamides, tetracyclines, and thiazides.

 

 

 

 

Phototoxic drug reaction. In phototoxic reactions, the drug may become activated by exposure to sunlight and cause damage to the skin. The skin's appearance resembles sunburn, and the process is generally has a fast onset. Ultraviolet A (UVA) radiation is most commonly associated with phototoxicity, but ultraviolet B (UVB) and visible light may also contribute to this reaction. Symptoms of phototoxic reaction may initially consist of a burning and stinging sensation; then redness occurs with in 24 hours of exposure to the sun in the exposed areas of the body. Common phototoxic drugs include certain antibiotics and antihistamines