Keratosis Pilaris on the Upper Arms of a Teenager

Tiny, asymptomatic “bumps” had been present for 4 years on the posterolateral surface of the upper arms of a 34-year-old woman. Similar but less severe eruptions also appeared on her forearms and anterior thighs.

Robert P. Blereau, MD of Morgan City, La, diagnosed keratosis pilaris, a keratinization disorder of unknown cause that is often seen in families and is thought to be an inherited dermatosis. Frequently, the condition begins in childhood. Histologic examination of the pinpoint follicular pustules shows inflammation outside the hair follicle.

Commonly affected sites are the posterolateral upper arms and anterior thighs. Tight clothing, scratching, and abrasive treatments can aggravate the lesions. Treatment is difficult; emollients, especially those containing lactic acid or urea, and topical salicylic acid or retinoic acid may be helpful. Class V topical corticosteroids also may be tried. If secondary folliculitis occurs, prescribe an oral antibiotic that is active against Staphylococcus aureus.