Natural history of keratosis pilaris.

A questionnaire was sent to 83 patients in the south Buckinghamshire area, in whom a primary diagnosis of keratosis pilaris (KP) had been made within the preceding 20 years. Of the 50 questionnaires returned, one was invalid, and 49 were evaluated. The age range of patients surveyed was 18 months-25 years; 61% were female and 39% male. Age of onset of KP was within the first decade in 51%, second decade in 35%, third decade in 12%, and fourth decade in 2%. Body sites affected were the arms (92%), legs (59%), face (41%), buttocks (30%) and eyebrows (8%). Other family members were affected by KP in 39%; 55% had no family history of KP, and 6% did not know. There was a personal history of atopy in 37%, 16% had associated dry skin, and 47% had neither. A seasonal variation in the severity of KP was noted in 80% of patients; 49% of these improved in the summer and 47% worsened in the winter. Overall, KP had improved with age in 35% of patients, remained unchanged in 43%, and worsened in 22%. The mean age of improvement was 16 years.