Keratosis Pilaris in an Older Teen: Late Presentation Not So Unusual
I read with interest the “What’s Your Diagnosis?” case of a 17-year-old girl with keratosis pilaris (CONSULTANT FOR PEDIATRICIANS, June 2010, page 197) by Drs Alexander K. C. Leung and C. Pion Kao, on your web site. In my experience, keratosis pilaris virtually always presents in children between 4 and 8 years of age who have at least one affected family member; the rash continues into adolescence and fades somewhat in adulthood. I have also found that the rash frequently involves the dorsum of the arm as well as the lateral aspect of the arm (A). In addition, the rash can appear anterior to the ear or in the “sideburns” area of the face (B). In rare cases, I have seen keratosis pilaris extend to the upper back or chest.
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Michael W. Cater, MD
Pediatrician
Tustin, Calif
We would like to thank Dr Cater for his interest in our “What’s Your Diagnosis?” case and we appreciate his thoughtful comments. The patient presented with a 7-month history of small, red papules on her arms and thighs.1 Keratosis pilaris usually develops during childhood and reaches its peak during adolescence.2 We agree with Dr Cater that a late onset is unusual, but the patient might not be a great historian.
As per our article, the prevalence of keratosis pilaris in adolescents of both sexes is estimated to be at least 50%, while up to 80% of girls may be affected.1 The disorder involutes spontaneously and is less common during adult life.3,4 An autosomal dominant mode of inheritance with incomplete penetrance has been postulated.3,4 The high prevalence and intensity seen at puberty suggests a hormonal influence.1-3 This is in agreement with Dr Cater’s observation that keratosis pilaris virtually always runs in families, begins in childhood, continues into adolescence, and fades somewhat in adulthood. In our experience, the sites of predilection favor the lateral aspects of the upper arms rather than the back of the arms.1-3
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Alexander K. C. Leung, MD
Clinical Professor of Pediatrics
University of Calgary
Pediatric Consultant
Alberta Children’s Hospital
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C. Pion Kao, MD
Clinical Assistant Professor of Pediatrics
University of Calgary
Pediatric Consultant
Alberta Children’s Hospital