Keratosis pilaris is a very common form of dry skin characterised by hair follicles plugged by scales
What causes it?
Keratosis pilaris is due to abnormal keratinisation of the lining of the upper portion of the hair follicle (the follicular infundibulum). Scale fills the follicle instead of exfoliating.
The tendency to keratosis pilaris has genetic origins, with autosomal dominant inheritance. This means that up to half of the children of an affected individual may display signs of keratosis pilaris to a variable degree.
Keratosis pilaris-like lesions can arise as a side effect of targeted cancer therapies such as vemurafenib.
Who gets it?
It affects up to half of normal children and up to three-quarters of children with ichthyosis vulgaris (a dry skin condition due to filaggrin gene mutations). It is also common in children with atopic eczema.
Although most prominent during teenage years, and least common in the elderly, it may occur in children and adults of all ages.
What are the clinical features?
Keratosis pilaris most often affects the outer aspect of both upper arms. It may also occur on the thighs, buttocks and sides of the cheeks, and less often on the forearms and upper back. The distribution is symmetrical.
The scaly spots may appear skin coloured, red (keratosis pilaris rubra) or brown (hyperpigmented keratosis pilaris). They are not itchy or sore.
It tends to be more prominent at times of low humidity, such as in the winter months.
Keratosis pilaris atrophicans
Keratosis pilaris atrophicans refers to uncommon forms of keratosis pilaris in which there are scar-like follicular depressions and loss of hair. These include:
• Keratosis pilaris atrophicans faciei (face)
• Erythromelanosis follicularis faciei et colli (face and neck)
• Ulerythema ophryogenes (eyebrows)
• Keratosis follicularis spinulosa decalvans (scalp)
• Atrophoderma vermiculata/ folliculitis ulerythematosa reticulata (pitted scarring of cheeks)
How is it diagnosed?
It is clinical diagnosis. Biopsy reveals:
• Epidermal hyperkeratosis
• Plugged hair follicles
• Mild superficial perivascular lymphocytic inflammation
What is the treatment?
No cure is available but following may be useful:
• Non-soap cleansers (soap may exacerbate dryness)
• Rubbing with a pumice stone or exfoliating sponge in the shower or bath
• Moisturising cream containing urea, salicylic acid or alpha-hydroxy acids
• Topical retinoids,
• Pulse dye laser treatment or intense pulsed light (IPL) – this may reduce the redness (at least temporarily), but not the roughness
• Laser-assisted hair removal
What is the outcome for it?
It may become less obvious in time. Atrophy or scarring with hair loss is permanent.
On DermNet NZ:
• Acne and other follicular disorders
• Ichthyosis Vulgaris
• Keratosis pilaris – Medscape Reference
• Keratosis Pilaris – British Association of Dermatologists
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