Chapter 33: Keratosis Pilaris Atrophicans

INTRODUCTION

Keratosis pilaris atrophicans (KPA) is a group of inherited disorders with three subtypes including (a) keratosis pilaris atrophicans faciei (KPAF), (b) atrophoderma vermiculatum (AV), and (c) keratosis follicularis spinulosa decalvans (KFSD). KPAF and AV present mainly on the face with KFSD often appearing on the eyebrow and AV most commonly seen on the cheeks, sparing the eyebrows and scalp. KFSD can affect the face, scalp, and trunk. Inheritance pattern can be autosomal dominant (KPAF, AV), recessive (AV), or X-linked (KFSD).

EPIDEMIOLOGY

Incidence: very rare; KPAF is the most common subtype

Age: KPAF and KFSD in infancy; AV in childhood

Sex: males are more severely affected in KFSD

PATHOGENESIS

Abnormal follicular keratinization of the upper section of the hair follicle that may later result in atrophic follicular scarring.

PHYSICAL EXAMINATION

Follicular plugging with erythema in early stages (Figure 33.1). Atrophic follicular scar formation with associated alopecia in later stages.

DIFFERENTIAL DIAGNOSIS

Keratosis pilaris, keratosis pilaris rubra, seborrheic dermatitis (KPAF), atopic dermatitis (KFSD), other etiologies of scarring alopecia (KFSD), acne scarring (AV), Rombo syndrome (AV), and KID syndrome (KFSD).

DERMATOPATHOLOGY

Dilated follicles with follicular hyperkeratosis and inflammation in early stages. Follicular fibrosis and atrophy in later stages.

COURSE

The course is chronic with no spontaneous resolution. With time, the erythematous follicular hyperkeratotic papules involute into depressed atrophic follicular scars with alopecia.

MANAGEMENT

There is no completely effective treatment for KPA. Multiple treatment options have been tried with only variable success. Patients should be counseled that therapy may not be effective.

• Topical therapy may, at best, produce modest benefit.

  • – Lactic acid and α-hydroxy acid lotions (10%–12%) applied twice daily may improve the textural roughness. However, they may produce irritation.

  • – Retinoids (tazarotene, retin-A) applied nightly may improve textural roughness. They may produce irritation.

  • – Corticosteroids applied sparingly may show improvement. Risk of facial atrophy limits their use.

• Systemic therapy

  • – Other options that have provided variable success include oral retinoids and dapsone.

  • – They are most helpful for the inflammatory stage of KPA, but provide minimal improvement in the follicular hyperkeratosis.

  • – They require careful monitoring for potential side effects.

• Laser therapy

  • – Pulsed dye laser (595 nm, 7-mm spot, 7–10 J/cm², DCD 40/20, pulse duration of 1.5–3 ms) can be effective in the treatment of the associated erythema of KPAF but will not significantly improve the textural roughness of KPA (Fig. 33.2A, B).

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