KERATOSIS PILARIS
Keratosis
pilaris is an extremely common dermatosis that in mild states can be considered
a variant of normal skin. It is usually brought to the clinician’s attention as
an afterthought, or the clinician observes the condition and tells the patient
about it for educational purposes. There are more severe forms of keratosis
pilaris in which patients present to the dermatologist for therapy. Many
distinct variants of keratosis pilaris exist, and they are named based on area
of involvement.
Clinical Findings: Keratosis pilaris is one of the most common
dermatoses and is thought by some to be a variant of normal. It is found in
more than 40% of the adult population and in as many as 80% of children. There
is no sex or race predilection. It typically begins soon after a child reaches
5 years of age. Most cases are asymptomatic and are of no concern to the
patient or of only cosmetic concern. The upper lateral arms are the most common
site of involvement. Small (1-2 mm), pink-to-red follicular hyperkeratotic
papules are present to a varying extent. Some are so fine that they are
noticeable only on palpation. Other cases are more widespread and can include
the upper thighs, shoulders, and cheeks. Widespread cases tend to be more
noticeable, and the small papules tend to be more inflammatory in nature.
This inflammatory form of keratosis
pilaris is also called keratosis pilaris rubra. It is typically manifested by
bright red, small, hyperkeratotic papules that may resemble pustules. They can
be mistaken for acneiform lesions. A small scraping of the inflammatory lesion
results in removal of a small keratin plug rather than the contents of an
acneiform pustule. The location on the outer arms and upper thighs also helps
to differentiate this condition from acne. Both keratosis pilaris and acne are
extremely common, and they are frequently seen together in the same patient.
Ulerythema ophryogenes is a
keratosis pilaris variant that manifests in early childhood. The lateral one
third of the eyebrow is affected with minute, red keratotic papules. Hair loss
of the lateral eyebrows is common. The rash may affect other parts of the face
and may heal with tiny pitted scars. It is almost always seen along with
keratosis pilaris. Over time, alopecia may develop in the affected regions,
especially the lateral eyebrows.
Atrophoderma vermiculata is one of
the rarest of the keratosis pilaris variants. It manifests as small,
hyperkeratotic plugs on the cheeks that resolve and leave behind small,
atrophic scars in a fine mesh-like pattern. Erythromelanosis follicularis
faciei et colli is similar in nature to atrophoderma vermiculata, but it lacks
any evidence of scarring. This condition has been reported to occur most
commonly in young men during the second and third decades of life.
Postinflammatory hyperpigmentation is another unusual feature not seen with
the other variants.
Keratosis follicularis spinulosa
decalvans is probably the least common keratosis pilaris variant. It is
inherited in a X-linked fashion and thus affects males. It is manifested by
areas of skin thickening and follicular plugging along with areas of scarring
alopecia. This condition may also affect the eyelashes. Corneal dystrophy and
blepharitis can be seen.
Pathogenesis: The exact etiology of keratosis pilaris is
unknown. It is believed to be caused by an abnormality in follicular
keratinization of the infundibulum.
Histology: Keratosis pilaris is rarely biopsied. A keratin
plug is the most prominent feature. The plug is typically 1 to 2 mm in diameter
and may lie on top of a meager lymphocytic infiltrate.
Treatment: No therapy is required for most cases. A
keratolytic moisturizer or humectant moisturizer works well. These include
lactic acid and salicylic acid based
moisturizers. After discontinuation, however, the rash of keratosis pilaris
returns over a period of a few weeks to months. Many other therapies have been
used. Vitamin A derivatives (e.g., tretinoin) are among the more commonly used
prescription medications. The cream is applied daily and has been successful in removing the redness and hyperkeratosis.
