BASICS
- Keratosis pilaris (KP) is a benign skin disorder resulting in hyperkeratinization of the hair follicles.
- Generally asymptomatic, often improving with age
DESCRIPTION
Small (1 to 2 mm), keratotic papules are localized to hair follicles, most frequently on the lateral aspects of the arms and thighs. Often described as chicken skin or goose bumps.
EPIDEMIOLOGY
There is a slight female predominance.
Prevalence
KP affects up to 80% of adolescents, often worsening during puberty, and up to 40% of adults.
ETIOLOGY AND PATHOPHYSIOLOGY
- The abrasive ( "sandpaper-like, " "chicken skin-like, " or "goose bump-like " ) texture of the skin is caused by excess buildup of keratin. An underlying hair may be found in some of the papules. In the inflammatory variant, mild perifollicular erythema is present.
- Autosomal dominant inheritance, with incomplete penetrance. KP is more frequent in obese patients.
Genetics
Autosomal dominant inheritance, with incomplete penetrance and variable expressivity, has been described, and many (30 " 50%) will report a positive family history of the disorder.
GENERAL PREVENTION
Moisturize to prevent excessive drying of the skin. Use only mild soaps (cleansers). Avoid hot showers.
COMMONLY ASSOCIATED CONDITIONS
Ichthyosis, xerosis, atopic dermatitis
DIAGNOSIS
HISTORY
- Patients often complain about a "rough " skin, sometimes with pruritus (which indicates inflammation).
- Most patients are asymptomatic, but some are concerned about their cosmetic appearance.
- Family history is positive in up to 50% of cases.
PHYSICAL EXAM
- Firm, minimally rough, 1- to 2-mm, follicle-based papules, some with perilesional erythema. Distribution is frequently symmetric.
- Most common on the lateral-proximal aspects of the arms and thighs; less common on the cheeks and gluteal areas
DIFFERENTIAL DIAGNOSIS
- Acne
- Folliculitis
- Rare dermatologic conditions (e.g., keratosis follicularis, lichen spinulosus, lichen nitidus, perforating folliculitis)
DIAGNOSTIC TESTS & INTERPRETATION
Diagnosis is visual. Dermoscopy may be of assistance if diagnosis is in doubt (1).
Diagnostic Procedures/Other
Skin biopsy if diagnosis in doubt
Test Interpretation
Hyperkeratosis, hypergranulosis, and follicular plugging are typical. A mild superficial perivascular inflammatory infiltrate may be noted.
TREATMENT
Daily measures to prevent dry skin, such as using mild cleansers, along with moisturizers, are the mainstay of treatment (2)[A]. Treatment improves symptoms but is not curative.
GENERAL MEASURES
Moisturize. Use emollients.
MEDICATION
First Line
- Lactic acid 12% creams/lotions (e.g., ammonium lactate: AmLactin Ultra, Lac-Hydrin)
- Urea (in 40 " 50% topical preparations)
Second Line
Emollient-based topical steroids (e.g., Cloderm, Locoid Lipocream)
ADDITIONAL THERAPIES
- Topical retinoids: tretinoin (Retin-A), adapalene (Differin), tazarotene (Tazorac)
- Tacrolimus (Protopic) ointment
SURGERY/OTHER PROCEDURES
Microdermabrasion, laser (Nd:YAG, pulsed dye)
ONGOING CARE
PROGNOSIS
Most cases improve with age.
COMPLICATIONS
Hair loss is rare. If the lateral eyebrows are involved, consider the diagnosis of KP atrophicans faciei (ulerythema ophryogenes).
REFERENCES
11 Panchaprateep R, Tanus A, Tosti A. Clinical, dermoscopic, and histopathologic features of body hair disorders. J Am Acad Dermatol. 2015;72(5):890 " 900.22 Hwang S, Schwartz RA. Keratosis pilaris: a common follicular hyperkeratosis. Cutis. 2008;82(3):177 " 180.
ADDITIONAL READING
Boza JC, Trindade EN, Peruzzo J, et al. Skin manifestations of obesity: a comparative study. J Eur Acad Dermatol Venereol. 2012;26(10):1220 " 1223.
CODES
ICD10
L85.8 Other specified epidermal thickening
ICD9
- 757.39 Other specified anomalies of skin
- 701.1 Keratoderma, acquired
SNOMED
Keratosis pilaris (disorder)
CLINICAL PEARLS
- KP is frequently mistaken for acne.
- Patients often self-manage with over-the-counter acne treatment products/medications originally prescribed for their facial acne.
- Daily measures to prevent dry skin, such as using mild cleansers, along with moisturizers, are the mainstay of treatment.
- Stop patients from exfoliating.