What is Keratosis Pilaris?

Keratosis Pilaris (KP) is a very common follicular disease manifested by the appearance of rough bumps on the back and outer sides of the upper arms. Sometimes, KP can also be present on the thighs and/or buttocks or virtually anywhere on your body except for palms and soles. There are numerous tiny rough spots in the affected area. Each one is a conical (spiny) plug resembling goosebumps. Sometimes, the skin surrounding the follicles might be slightly irritated, making it look like a red "rash". Keratosis Pilaris is completely harmless but sometimes unsightly.

---Keratosis Pilaris on the back of the upper arm---

When keratosis pilaris occurs on the cheeks, the affected area is red as well as feeling rough. The characteristic "reddish" aspect of this type of facial KP gives it the clinical name of KP Rubra Faceii. Another variant on the face, called "keratosis pilaris atrophicans faciei", causes a worm-eaten like atrophy of skin. When the outer eyebrows are affected the condition is known as "ulerythema ophryogenes". Face occurrences often affect babies where it tends to be most obvious on the cheeks. It may remain for years but generally becomes less obvious in adult life; keratosis pilaris is uncommon in elderly people.

KP is estimated to affect roughly half of the world's over-all population. The inheritance pattern of the condition is dominant. This means that only one copy of the KP gene is required to result in a person developing this condition. The practical implications of this are that if one parent has KP, the chance of the couple's child having KP is over 50%. If both parents have the condition, the odds are even higher.

Why KP occurs?

The bumps of KP result from the way in which scales are shed from the outer skin around KP affected hair follicles. In these follicles, the outer skin scales are excessively adherent and do not shed easily. This phenomenon is known as abnormal keratinization or hyperkeratinization. The fact that it is localized to the individual follicles and occurs in each and every one in a certain area, explains its characteristic "millions of bumps" appearance.

Sometimes, this hyperkeratotic buildup entraps the hair within the follicle. The trapped hair gets bunched up and may lead to a red irritated bump that may fill with pus. These pus filled red bumps are often confused with bacterial folliculitis or acne.

People with a history of skin allergies are most susceptible to this condition. The papules tend to occur in association with allergic dermatitis and several types of xerotic (dry) skin disorders. Both of these conditions have a strong hereditary link.

Keratosis pilaris tends to be more severe during the winter months or other times of low humidity when skin dries out. Areas where relative humidity is low have a higher incidence of Keratosis Pilaris.