ABSTRACT
DEFINITION AND CLINICAL FEATURES Keratosis pilaris is a dry skin disorder due to abnormal keratinization of hair follicle epithelium. Mild forms are very common and start in early childhood, peaking in adolescence, and improving with age. Its features are prominent follicular hyperkeratosis with plugging that predominantly affects the extensor aspects of the upper arms (118) and legs and the buttocks. Perifollicular erythema (keratosis pilaris rubra) may occur. It may be associated with facial erythema and atrophy of the eyebrows (ulerythema ophryogenes) and pitted atrophic scars on the cheeks (atrophoderma vermiculata). A genetically distinct variant involves the scalp and leads to progressive scarring alopecia (keratosis follicularis spinulosa decalvans). Keratosis pilaris may be inherited as an autosomal dominant trait and is associated with ichthyosis vulgaris.
