Keratosis pilaris

What it means

An anomaly of the hair follicles of the skin that typically presents as small, rough, brown folliculocentric papules distributed over characteristic areas of the skin, particularly the outer-upper arms and thighs.

Keratosis pilaris is characterized by abnormal keratinisation of the lining of the follicular infundibulum (the upper portion of the hair follicle). Keratin (i.e., scale) fills the follicle instead of exfoliating. Clinically, the keratotic plugs have been referred to as the carpet tack sign since they project up similar to carpet tacks.

Rare diseases that can present with this8

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Carpet tack sign · Follicular keratosis · Follicular keratotic plug · Follicular plugging · Hyperkeratosis pilaris · Lichen pilaris