Section 12: Papulosquamous Diseases

Seborrheic dermatitis This term refers to a scaly, crusting, and erythematous eruption that is most common in infancy (ages 2-12 weeks), where it tends to favor the scalp, diaper area, and intertriginous folds. Figure 12-1 is an illustration of the process in the scalp where it is often referred to as cradle cap.

Figure 12-2 illustrates severe involvement in the eyebrows, a common area of involvement. A subset of infants with seborrheic dermatitis will go on to develop atopic dermatitis and it sometimes may be difficult to differentiate between these two conditions.

Seborrheic dermatitis Figure 12-3 shows very severe facial and scalp involvement. Some basic principles are that the lesions of seborrheic dermatitis are usually well circumscribed, do not itch, and localize toward the face, scalp, and intertriginous areas. The greasy red-orange scaliness of seborrheic dermatitis is somewhat helpful in differentiating this disorder from atopic dermatitis.

Figure 12-4 shows a more extensive process that is nearly generalized, dry, and scaly. Seborrheic dermatitis has its onset early in infancy and usually resolves by 1 year of age; atopic dermatitis tends to be more persistent.

Seborrheic dermatitis The cause of this very common condition remains unknown. Although it favors areas with an increased number of sebaceous glands, there is no evidence that seborrheic dermatitis is a disease of sebaceous glands or is related to excessive sebum production.

Some studies have suggested that the lipid composition of sebum in seborrheic dermatitis may be abnormal. Bacteria and yeasts are often present in areas of involvement, but neither Candida albicans nor Pityrosporum ovale has been shown to be an etiologic agent.

Seborrheic dermatitis Seborrheic dermatitis, common during infancy, is relatively unusual during later childhood. It resurfaces as a problem during adolescence and then seems to become progressively more common through adult life. The adolescent variant primarily involves the scalp, forehead, tarsal margins of the eyelids (blepharitis), ears, and nasolabial folds. Seborrheic dermatitis is easily controlled but not curable. Treatment may consist of the topical application of ketoconazole cream or a mild topical steroid. The frequent use of tar shampoos is particularly helpful in the control of seborrheic dermatitis of the scalp.

During puberty and in adulthood, seborrheic dermatitis occurs not only on the scalp and face but also on the chest, on the back, and in intertriginous spaces such ...