What is keratosis pilaris?
Keratosis pilaris is a very common form of dry skin characterised by hair follicles plugged by scale.
Who gets keratosis pilaris?
Keratosis pilaris 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 causes keratosis pilaris?
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.
What are the clinical features of keratosis pilaris?
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.
Keratosis pilaris 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 vermiculatum/ folliculitis ulerythematosa reticulata (pitted scarring of cheeks)
How is keratosis pilaris diagnosed?
Keratosis pilaris is a clinical diagnosis.
- Epidermal hyperkeratosis
- Plugged hair follicles
- Mild superficial perivascular lymphocytic inflammation
What is the treatment for keratosis pilaris?
No cure is available for keratosis pilaris. The 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 alphahydroxy 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 keratosis pilaris?
Keratosis pilaris may become less obvious in time. Atrophy or scarring with hair loss is permanent.