Encyclopedia of Health and Medicine

actinic keratosis 133
and scrubbing can aggravate acne, causing
increased inflammation and irritation. Harsh soaps
that dry the skin may temporarily reduce surface
oils but can cause flaking and other problems.
Using an astringent according to the doctor’s
instructions can draw excess oils from the sebaceous
structures without so much irritation to the
surrounding skin. Dermatologists often recommend
lubricating lotions and creams that do not
block the pores to help maintain the skin’s moisture.
See also DERMATITIS; FOLLICULITIS; KERATOCYTE;
LESION; MILIARIA; NODULE; PAPULE; ROSACEA; SEBA-
CEOUS GLAND.
acrochordon A polyp that commonly grows
externally from SKIN folds, such as those around
the eyelids and on the neck, underarms, and
groin. Also called a skin tag or fibroepithelial
polyp, an acrochordon is noncancerous and harmless
(benign). Doctors do not know what causes
acrochordons to develop. Some acrochordons contain
one of the HUMAN PAPILLOMAVIRUS (HPV) strains,
though others do not. Acrochordons become more
common with advanced age, and are most likely
to appear in people who are between the ages
of 50 and 75. Unlike intestinal polyps, acrochordons
do not become cancerous. The dermatologist
may remove an acrochordon that is in a location
of frequent irritation or cosmetically unacceptable.
See also INTESTINAL POLYP; PLASTIC SURGERY.
actinic keratosis Precancerous growths (lesions)
on the SKIN, also called solar keratosis, that
develop as a consequence of damage from overexposure
to the sun. Actinic keratosis becomes more
common with advancing age. Lesions are most
common on the face, scalp, chest, hands, and
arms though can develop anywhere on the body
that receive extensive sun exposure. In their early
stages, the lesions appear scaly and rough, and
bleed easily. In later stages, the lesions acquire a
wartlike appearance. Most squamous cell SKIN
CANCER arises from actinic keratosis. Removing the
lesions prevents them from developing into CAN-
CER. Between 10 and 20 percent of untreated
actinic keratosis develops into squamous cell skin
cancer, though it is not possible to determine
which lesions will remain benign and which will
turn cancerous.
Symptoms and Diagnostic Path
The lesions of actinic keratosis follow a typical and
consistent progression of symptoms. Actinic keratosis
begins with a small, scaly patch of skin that
may itch. It often appears to heal or peel off, then
recurs. The LESION may be grayish, may reddened
(erythematous), or may be the same color as the
skin. Most people first feel rather than see the
lesion. As changes to the skin cells at the site continue,
the lesion becomes more defined and
apparent. The lesion may resemble a wart, or may
become hardened and overgrown, developing a
tough, thick texture (hyperkeratosis).
Because the progression of actinic keratosis is
so characteristic, the dermatologist generally
makes the diagnosis on the basis of appearance
and history of sun exposure. The dermatologist
may choose to biopsy larger or suspicious lesions
to determine whether they have progressed to
squamous cell skin cancer. Unless such suspicion
exists, there is no need for biopsy because the
standard treatment is to remove the lesion, which
consequently eliminates the lesion’s risk for evolving
into a cancer.
Treatment Options and Outlook
Treatment for actinic keratosis is removal of existing
lesions coupled with regular (every 6 to 12
months) examinations of the skin to detect new
lesions. Methods for removing the lesions include
• cryotherapy, such as liquid nitrogen, which
freezes the lesion, causing the cells to die and
slough away
• electrocautery, which burns away the lesion
• curettage, in which the dermatologist scrapes
off the lesion using a sharp surgical blade
• topical application of a chemotherapy agent,
which causes the cells in the lesion to die and
slough away
• photodynamic therapy, in which the dermatologist
applies a photosensitive chemical that
accumulates in the affected cells and then
administers certain frequencies of light exposure
that cause the cells containing the photosensitive
chemical to die