What is keratosis pilaris?

What is Keratosis Pilaris?

Keratosis pilaris (KP) is a common, benign genetic skin disorder characterized by follicular hyperkeratosis that presents as small, rough, keratotic papules around hair follicles, creating a "gooseflesh" or stippled appearance on the skin. 1, 2

Pathophysiology

• KP results from abnormal keratinization where dead skin cells plug the hair follicles, leading to the characteristic folliculocentric papules 3, 2
• Inherited mutations in the FLG gene (filaggrin) and ABCA12 gene have been implicated in the etiology of this condition 1
• The disorder represents a family of follicular conditions, with KP simplex being by far the most common variant 1

Clinical Presentation

The condition manifests as small, hard, keratotic papules with variable perifollicular erythema, most commonly affecting the extensor surfaces of the upper arms, thighs, and buttocks. 1, 2

• The papules are typically gray and keratotic, creating a rough texture to the skin 4
• Patients are usually asymptomatic, with complaints limited to cosmetic concerns or occasional mild pruritus 2
• The condition predominantly affects women and commonly appears in adolescence and young adulthood 4

Clinical Variants

• KP simplex: The most common form with gray keratotic papules 1, 4
• Keratosis pilaris rubra: Characterized by more prominent erythema and may progress to atrophic forms 1, 4
• Rare subtypes include erythromelanosis follicularis faciei et colli and the spectrum of keratosis pilaris atrophicans 1

Associated Conditions

• KP may be associated with ichthyosis vulgaris and palmar hyperlinearity 1
• The association with atopic dermatitis is less consistent than previously thought 1
• Can occur in association with genetic syndromes such as Noonan syndrome or vitamin deficiency disorders 4
• In cardio-facio-cutaneous syndrome, keratosis pilaris (follicular hyperkeratosis of extremities and/or face) is seen in the majority of cases 5

Differential Diagnosis

Key conditions to distinguish from KP include: 1

• Lichen spinulosus
• Phrynoderma (vitamin A deficiency)
• Ichthyosis vulgaris
• Trichostasis spinulosa

Important Clinical Caveats

• KP is a chronic condition with no permanent cure; treatments provide only temporary improvement 4
• The cosmetic appearance can lead to psychosocial distress despite the benign nature of the condition 6
• Diagnosis is typically clinical and does not require biopsy 2