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CommonFollicularICD-10 L85.8

Keratosis pilaris

KP · keratosis pilaris alba / rubra · chicken-skin · follicular keratosis

Keratosis pilaris is an extremely common autosomal-dominant follicular keratinisation disorder affecting up to 50-80% of adolescents and 30-40% of adults. Characterised by small, rough, follicular papules on the extensor upper arms, thighs, buttocks and cheeks, it represents one of the commonest UK dermatology presentations and is the principal DDx for a range of follicular eruptions including EGFR-inhibitor folliculitis, lichen spinulosus, Darier disease and chronic atopic eczema.

CurrentLast reviewed 16 May 2026
Clinical image of Keratosis pilaris
Keratosis pilaris. Image sourced from DermNet New Zealand. Used under CC BY-NC-ND 4.0. No endorsement implied.

Clinical features

  • Small (1-2 mm) flesh-coloured to red-brown follicular papules; often with central keratotic plug.
  • "Sandpaper" or "goose-bump" texture.
  • Sites:
    • Extensor upper arms (commonest).
    • Anterior / lateral thighs.
    • Buttocks.
    • Cheeks (paediatric).
    • Trunk.
  • Surrounding erythema (rubra variant) common in fair-skinned patients.
  • Variants:
    • KP alba: white / skin-coloured papules without erythema.
    • KP rubra: prominent surrounding erythema.
    • KP rubra faciei: facial / preauricular erythema with papules — paediatric / adolescent variant.
    • Atrophic KP variants: keratosis follicularis spinulosa decalvans, atrophoderma vermiculatum, ulerythema ophryogenes — associated with Noonan, cardio-facio-cutaneous, Rubinstein-Taybi syndromes.
  • Often improves with age; worse in winter / dry climate.
  • Strong family history (autosomal dominant); often associated with atopic background, ichthyosis vulgaris, obesity.

Pathogenesis

  • Follicular hyperkeratinisation with keratin plug formation.
  • Variable circular hair within plug.
  • Filaggrin (FLG) mutations in some patients — overlap with atopic eczema and ichthyosis vulgaris.
  • Autosomal dominant inheritance pattern.
  • Triggers / aggravators: dry climate, low humidity, harsh soaps, friction.

Differentials

  • EGFR-inhibitor folliculitis — drug history; truncal predominance; rapid onset.
  • BRAF / MEK inhibitor follicular eruption.
  • Pityrosporum folliculitis — itchy; back / chest; KOH+.
  • Bacterial folliculitis.
  • Lichen spinulosus — grouped follicular keratotic plugs; child / adolescent.
  • Darier disease (focal acantholytic dyskeratosis) — keratotic papules in seborrhoeic distribution; ATP2A2 mutation.
  • Atopic eczema background often coexists.
  • Chronic friction folliculitis.
  • Phrynoderma (vitamin A deficiency) — rare in UK.

Management

  • General:
    • Counsel: benign; chronic but improves with age; cosmetic only; no systemic associations in classical form.
    • Avoid harsh soaps, hot water.
    • Soap substitutes; lukewarm short showers.
  • Topical:
    • Urea 10-40% cream or lotion (mainstay).
    • Lactic acid 5-12% (AmLactin / Calmurid).
    • Salicylic acid 2-6%.
    • Ammonium lactate.
    • Glycolic acid (alpha-hydroxy acid).
    • Tretinoin 0.025-0.05% or adapalene 0.1% — for thicker plugs.
    • Mild topical corticosteroid (hydrocortisone 1% / clobetasone butyrate) for KP rubra erythema, short courses.
  • Procedural:
    • Microdermabrasion (cosmetic).
    • Vascular laser (PDL / IPL) for refractory KP rubra faciei.
    • Chemical peels (glycolic acid).
  • Counsel:
    • Lifelong condition; improves with age in most.
    • Cosmetic concern is main issue; functional impact minimal.
    • Combination topical regime + bland emollient.

References

  1. Hwang S, Schwartz RA. Keratosis pilaris: a common follicular hyperkeratosis. Cutis. 2008;82:177-180.
  2. Thomas M, Khopkar US. Keratosis pilaris revisited: is it more than just a follicular keratosis? Int J Trichology. 2012;4:255-258.
  3. Reddy BSN. Keratosis pilaris: an overview. Indian J Dermatol Venereol Leprol. 2001;67:289-293.
  4. British Association of Dermatologists. Keratosis pilaris — patient information leaflet. London: BAD; 2023.

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