4 – Psoriasis
This common skin disease affects up to 2% of persons in the United States. Psoriasis is usually thought of as an adult disease; however, in 2% of affected persons, it develops before the age of 2 years. The elbows, knees, hands, feet, and scalp are the areas of the body that are most often affected. However, there is a form of psoriasis known as inverse psoriasis that affects the folds. Inverse psoriasis is seen in both adults and children; in infants it can present as a diaper rash (Figure B).
Typical clinical findings in inverse psoriasis are a diffuse, light pink erythema that starts in the groin folds; a dry appearance (as opposed to the maceration seen in candidiasis); and an absence of satellite pustules. Additional, more classic psoriatic lesions may be seen elsewhere on the body. A history of psoriasis in other family members can help confirm the diagnosis, but a family history is not always present.
Treatment of diaper psoriasis consists of intermittent use of mild topical corticosteroids, similar to those used to treat seborrheic dermatitis. If mild corticosteroids are not effective as monotherapy, topical immunomodulators may be added after a discussion of their offlabel use and black box warning is had with the family.
Seborrheic dermatitis (not pictured) is another noninfectious skin disease that commonly affects the diaper area. Although seborrheic dermatitis of the scalp, or cradle cap, is familiar to all pediatricians, seborrheic dermatitis can affect the entire body. The most common presentation of seborrheic diaper dermatitis is a diffuse diaper rash in association with classic cradle cap. The diaper rash can be differentiated from candidiasis on the basis of findings of diffuse erythema without accentuation of the folds and without satellite pustules.
Seborrheic dermatitis is thought to be at least in part a hypersensitivity reaction to an overgrowth of Malassezia yeast, which is found on the scalp and in the diaper area during the first 6 to 12 months of life. Treatment includes application of topical azole antifungal creams or washes in conjunction with intermittent use of very mild topical corticosteroids, such as hydrocortisone(Drug information on hydrocortisone) 1% to 2.5% cream. Again, combination creams containing both an antifungal and a mid- to high-potency corticosteroid should never be used in the groin area.