Folliculitis spinulosa decalvans: an uncommon entity within the keratosis pilaris atrophicans spectrum

Folliculitis spinulosa decalvans is an uncommon condition characterized by follicular hyperkeratosis, followed by scarring alopecia. We report a 12-year-old boy affected by keratotic papules of the scalp and keratosis pilaris of the limbs who developed erythema, pustules, and scale crusts on the scalp associated with scarring alopecia. Histologic examination showed follicular and interfollicular hyperkeratosis, follicular plugging, mild inflammation, and focal scarring. A transient remission of the inflammatory changes on the scalp was obtained after treatment with isotretinoin. The follicular spinulous hyperkeratosis persisted. A severe relapse of the scalp inflammation was observed during a 2-year follow-up.