Dermatologists Dr Derrick Phillips and Dr Kohei Matsumoto introduce a variety of treatment options for keratosis pilaris
Keratosis pilaris (KP) is a common skin condition which causes abnormal follicular keratinisation, producing a characteristic papular rash on the extensor surfaces of the upper arms, upper legs and buttocks.1
It may also affect other areas such as the face and trunk.1 KP typically presents in early childhood, and affects 50-80% of adolescents and approximately 40% of adults.1 It is thought to be a genetic disorder, and most cases fit an autosomal dominant pattern of inheritance with variable penetrance.1
The cause of KP is not fully understood, however, it has been associated with mutations in the FLG gene encoding the key epidermal protein filaggrin.1 KP is benign and usually asymptomatic.1
However, in our experience, it can be a source of considerable distress, due to the cosmetic appearance. Although there is no cure, there are effective treatment options available to manage this condition.
Patients with KP are usually asymptomatic, and most complaints are due to its cosmetic appearance, the feeling of rough-textured skin and occasional mild pruritus (itching). This may in turn lead to psychological distress affecting patients’ quality of life. KP typically presents as keratotic follicular papules involving extensor aspects of proximal arms, legs and buttocks, with variable erythema.2 It may also involve the face, trunk and distal extremities.2
Variants of KP include keratosis pilaris rubra (KPR); where there is marked perifollicular redness, which may manifest as a violaceous hue or hyperpigmentation in skin of colour. The papules of KP can also appear greyish white without erythema, which is termed keratosis pilaris alba (KPA).2 Keratosis pilaris atrophicans faciei (KPAF) is an uncommon form of KP with associated scar-like follicular depressions and gradual loss of hair on the lateral aspects of the eyebrows.3 KP tends to improve with age, although it may be more prominent and inflamed during winter months as it is often exacerbated by cold.4
KP commonly occurs in the setting of atopic eczema and ichthyosis vulgaris, both of which are associated with fillagrin mutations.1 It can be seen in scarring hair loss conditions and is prevalent amongst patients with diabetes mellitus and obesity.1 KP is also associated with some genetic conditions including cardio-fasciocutaneous syndrome, ectodermal dysplasia, keratitis-ichthyosis-deafness (KID) syndrome, prolidase syndrome and trisomy 21.1
The diagnosis of KP is clinical, and it is based on findings of spiky keratotic papules in the typical distribution. Therefore, skin biopsy is not usually necessary unless there is concern about one of the scarring subtypes. However, a classical histopathological finding would be the distension of the follicular orifice by a keratinous plug that may contain one or more twisted hairs.5 Although KP tends to improve with age, for some patients the condition may persist, become particularly widespread or have intense erythema. There is no cure for KP, but there are various treatments available to improve cosmesis and symptoms. KPAF often requires more aggressive treatment, although the options remain the same.
Emollients and keratolytics
Patients with KP should be encouraged to avoid practices that dry out the skin, such as use of detergent soaps and having hot baths or showers.4 Emollients can alleviate mild KP by tackling dryness, particularly if they contain keratolytic ingredients such as urea, lactic acid and salicylic acid.2
Topical retinoids (such as Tretinoin, Adapalene, Tazarotene and Trifarotene, all of which are prescription treatments) is a treatment option that can be considered when moisturising with emollients has failed. Retinoids are vitamin A derived compounds that are effective at treating follicular disorders such as acne and KP. Retinoids act to normalise desquamation by reducing keratinocyte proliferation and promoting differentiation. They can cause dryness and irritation, making them unsuitable for patients with sensitive skin or active eczema. They are also teratogenic, therefore are not to be prescribed for pregnant women.6
Short courses of mild to moderate potency topical steroid can be used in cases where KP lesions are particularly inflamed.2 Topical corticosteroids can be prescribed by any doctor or prescribing nurse, but dermatologists may prescribe more potent steroids. Treatment is discontinued once inflammation improves, usually within seven days.2
Treatment with oral retinoids (for example, Isotretinoin) may be considered when there is no improvement with topical measures. Isotretinoin reverses abnormal follicular keratinisation, but also shrinks the sebaceous glands, leading to dryness of the skin and mucous membranes.7 Extra care must be taken when prescribing retinoids in female patients of childbearing age as they are teratogenic, leading to harm to the unborn foetus. It must be avoided in pregnant patients and contraception must be recommended in women of childbearing age.6 Treatment with oral retinoids can also preclude the use of ablative lasers and mechanical dermabrasion for six months.8
Laser and light devices
Treatment with lasers and intense pulsed light (IPL) can be considered when there is a lack of improvement with conventional therapies. They have emerged as an attractive treatment option as they can address the erythema and skin texture that is characteristic for KP. In our experience, a tailored approach is required for the best cosmetic outcome. A cautious approach is required when using energy devices in skin of colour to avoid post-inflammatory hyperpigmentation.9
Quality switched Nd:YAG lasers
QS Nd:YAG laser therapy is a selective photothermolysis device which targets haemoglobin, melanin and water within the dermis, improving pigmentation, erythema and skin texture/roughness. Due to the longer wavelength compared to other lasers, it may reach deeper dermal structure such as the hair follicles, leading to resolution of follicular plugging through exfoliation and destruction of hair follicles. The slow heating of large blood vessels also promotes coagulation and contraction of the surrounding collagen. This causes skin tightening, leading to improvement of skin texture in KP.10
Potential side effects include a stinging sensation during treatment, post-treatment erythema, reactivation of herpes simplex and scarring.11 QS Nd:YAG lasers have a reduced risk of these side effects compared to traditional lasers as they have shorter pulses which means the temperature in the target molecules (or tissues) rises and rapidly falls, reducing damage to surrounding tissues.12
Diode laser 810 nm
Diode lasers have minimal effect on skin erythema but are particularly effective in the non-erythematous variant of KP, keratosis pilaris alba. Side effects include transient post-inflammatory hyperpigmentation.13
CO2 lasers are a 10,600 nm laser targeting the absorption peak of water.14 Full and fractional ablation can be used to destroy lesions and resurface affected areas, improving skin texture and dyspigmentation in patients with KP. Side effects include erythema and dyspigmentation.9
Pulsed dye laser
PDL induces apoptosis of vascular endothelial cells and may also lower vascular endothelial growth factor levels, helping improve erythema. It is generally well tolerated, but reported side effects include pain, dyspigmentation and purpura.15
Intense pulsed light
IPL relies on selective photothermolysis, and through optical cut off filters, emits various ranges of wavelengths which reach the target chromophores. This results in effects on the follicular papillae and hair bulge, erythema and hyperpigmentation. Side effects include pain, superficial burning and transient erythema. It should be noted that IPL emits a large range of wavelength that also induces absorption by melanin. This may pose a risk of permanent damage to melanocytes leading to persistent hypo- or depigmentation.
Contraindications to laser and light treatment
There are numerous contraindications to be considered with light and laser treatments. These include patients taking photosensitising medications (such as Amiodarone or tetracyclines) and use of oral retinoids within six months before treatment. Photodermatoses (like porphyria or xeroderma), anticoagulation, active skin infections, recent unprotected sun exposure, pregnancy and light triggered epilepsy are also contraindications to laser treatment. Specific UK guidance is set by the British Medical Laser Association.8
Consider a variety of treatments
KP is a common skin condition which is frequently overlooked, with some patients not even being aware that they can seek treatment for it. It is benign and usually asymptomatic, but patients can find its appearance distressing. Most cases of KP can be effectively managed with topical keratolytics and retinoids, but severe cases may warrant treatment with oral retinoids or lasers.
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