American Medical Association Family Medical Guide - American Medical Association [755]
Irritant dermatitis
Some people are especially sensitive to particular substances. Irritant dermatitis worsens during the winter (when the air contains less moisture) or with the use of soap and water because of excessive dryness of the skin. The skin of an older person tends to be dry, particularly on the legs, leading to mild redness, flaking, and irritation. People who take frequent hot showers or baths can develop irritant dermatitis. Dishwashing liquids, detergents, fabric softeners, household cleaners, and shampoos often irritate the skin on the hands (see page 120) and especially the skin over the knuckles.
Infantile eczema
Infantile eczema is a type of atopic dermatitis (see left) or seborrheic dermatitis (see next page) that is common in babies and young children and may indicate that the child will develop other allergies later in life. The skin reaction may range from a slight rash to small red pimples that ooze and crust over when scratched. Small areas of the body such as the cheeks and chin (see page 120) may be affected, especially in infants. In children, the rash often develops behind the knees or inside the elbows, but it can affect the entire body. The pimples may become infected, especially in the warm, moist diaper area (see page 120), where bacteria can live and grow rapidly.
Many infections that affect the skin (such as chickenpox; see page 439) can become severe in children with eczema. Infantile eczema can come and go for several years or go away completely without treatment after a few months. Most children outgrow it by puberty. However, in some children and adolescents, hormones, stress, and use of irritating skin-care products such as cosmetics or hair gels can cause the disorder to flare up.
WARNING!
Eczema and Allergy to Eggs
If your child has eczema caused by an allergy to eggs, tell his or her pediatrician. The measles, mumps, and rubella vaccination (MMR; see page 376) is produced using eggs, so, to have the vaccination, your child may have to be slowly and gradually made less sensitive to the vaccine. Your doctor will recommend giving your child either increasing doses of the vaccine (which all children must receive) or diluting the vaccine and giving it in frequent small amounts.
Seborrheic dermatitis
Seborrheic dermatitis (see page 120) affects different people in different ways. In adults, the creases from the sides of the nose to the corners of the mouth may become red, flaky, and itchy. In men, this inflammation can extend to the beard area and the hair-covered areas of the chest and back. The condition also may affect skin creases in other parts of the body, such as those in the groin or armpits or under the breasts. Dandruff (see page 1075) is flaking of the skin of the scalp caused by a mild form of seborrheic dermatitis. The cause of seborrheic dermatitis is unknown, but it tends to run in families and comes and goes over several years. In infants, seborrheic dermatitis takes the form of infantile eczema (see previous page). On a baby’s scalp, it is known as cradle cap (see page 387).
Symptoms
In dermatitis, the skin is usually dry, itchy, and red, possibly with flaking, scaling, or blistering. Sometimes dermatitis causes small bumps (papules) or small, rough bumps on the face, upper arms, and thighs (a condition called keratosis pilaris). In severe cases, dermatitis can result in blisters, darkening of the skin (hyperpigmentation), thickened skin from constant scratching and rubbing (lichenification), and bacterial infection from constant scratching.
Seborrheic Keratoses
Seborrheic keratoses are rough, round, or oval patches of dark skin (see page 121) up to about 1 inch across that have a crusty, greasy appearance. They can be flat or slightly raised. Seborrheic keratoses are common after middle