Actinic keratosis (AK), also known as solar keratosis, is the result of prolonged exposure
to ultraviolet radiation via sunlight or indoor tanning. It is a small crusty or scaly bump or horn that
arises on the skin surface. The base may be light or dark, tan,
pink, red, or a combination of these...or the same color as
your skin. The scale or crust is horny, dry and rough, and is
often recognized by touch rather than sight. Occasionally it
itches or produces a pricking or tender sensation. It can also
become inflamed and surrounded by redness. In rare instances,
actinic keratoses can bleed.
The skin abnormality or lesion develops slowly and usually
reaches a size from an eighth to a quarter of an inch (2mm to
4mm) but can sometimes become quite large. Early on, it
may disappear only to reappear later. It is not unusual to see
several AKs at a time. AKs are most likely to appear on the
face, lips, ears, scalp, neck, backs of the hands and forearms,
shoulders and back—the parts of the body most often exposed
Actinic keratoses can be the first step leading to squamous
cell carcinoma (SCC). Some studies show that ten percent do
advance, and 40-60 percent of SCCS begin as untreated AKs.
The term "precancerous" is used because AKs are more likely to turn malignant than healthy
skin. Precancerous growths (lesions) are visible to the naked
eye and they look different from normal cells when examined
under a microscope. When malignant changes occur to the skin, but the malignant cells haven't spread
below the top layer of the skin (epidermis), they are called
early cancers, or "carcinoma in situ".
Freezing with liquid nitrogen spray is the most common way to remove AKs. The skin usually heals within 2-6 weeks with minimal scarring. If the AK persists the area may be retreated or it may be biopsied to rule out skin cancer. Perscription creams such as imiquimod, 5FU, or diclofenac may be useful. Applying a sunscreen every morning is a good way to prevent developing AKs.