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Actinic Keratosis
What is actinic keratosis?
Actinic keratosis, also known as a solar keratosis,
is a scaly or crusty bump that arises on the skin surface. The base may be light or dark,
tan, pink, red, 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.
Actinic keratosis can be the first step in the
development of skin cancer, and, therefore, is considered a precancerous skin condition.
The presence of actinic keratoses indicates that sun damage has occurred and that any kind
of skin cancer can develop.
What do actinic keratoses look like?
The skin abnormality or lesion develops slowly to reach a
size that is most often from an eighth to a quarter of an inch. It may disappear and
reappear later. It is not unusual to see several actinic keratoses at a time.
A keratosis is most likely to appear on the face, ears,
bald scalp, neck, backs of hands and forearms, and lips. It tends to lie flat against the
skin of the head and neck and be elevated on arms and hands.
It is estimated that up to 10 percent of active lesions,
which are redder and more tender than the rest, will take the next step and progress to
squamous cell carcinomas.
How does actinic keratoses develop?
The lesions are usually not
life-threatening, provided they are detected and treated in the early stages. However, if
this is not done, they can grow large and invade the surrounding tissues and, on rare
occasions, metastasize, or spread, to the internal organs.
The most aggressive form of keratosis, actinic
cheilitis, appears on the lips and can evolve into squamous cell carcinoma. When
this happens, about 20 percent of these carcinomas metastasize to other parts of the body.
Who is affected by actinic keratoses?
Sun exposure is the cause of almost all actinic keratoses.
Sun damage to the skin accumulates over time, so that even a brief exposure adds to the
lifetime total. Certain groups of people are more at risk than others:
- People who have fair skin, blonde or red hair, and blue,
green, or gray eyes are at the greatest risk, but darker-skinned people can develop
keratoses if they expose themselves to the sun without protection.
- African-Americans rarely have these lesions.
- Individuals who are immunosuppressed as a result of
cancer chemotherapy, AIDS, or organ transplantation, are also at higher risk.
One in six people will develop an actinic keratosis in
the course of a lifetime, according to some estimates. Older people are more likely than
younger ones to have actinic keratoses, because cumulative sun exposure increases with
age.
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