Actinic (or solar) keratosis (literally “sun-induced”; aktis, ray in Greek) is the most common premalignant
lesion in humans. It is a sun-related growth that affects an estimated 60% of individuals older than 40,
typically the fair-skinned and blue-eyed easy burners, who tan poorly and have occupations/hobbies that
expose them to lots of sun. Most have at least one actinic keratosis per year. Many have several.
Histologically, AK represents a partial-thickness atypia of the epidermis and, if left untreated, may degenerate into squamous cell carcinoma (SCC). Lesions usually develop as a single, small erythematous plaque, 3–10 mm in diameter, typically located over exposed surfaces, such as nose, forehead, temples, cheeks, ears, bald scalp, forearms, and dorsum of the hands (but also the back, chest, and legs). The lesions have an erythematous base that is usually covered by a scale (hyperkeratosis), often on a background of solar damaged skin, with telangiectasias, elastosis, pigmented lentigines, and multiple erythematous
keratoses. They flare and become more visible during time of immune suppression, acute sun exposure, or
chemotherapy.
One in 20 eventually breaks through into the dermis, becoming invasive and possibly
metastatic. These are typically the most elevated, erythematous, and indurated. Although more common
in older individuals, AK may also affect people in their 20s and 30s, especially fair-skinned redheads and
blonds who do not use sunscreen and live in the “sun belt” (Australia is the nation with the highest AK
prevalence).
lesion in humans. It is a sun-related growth that affects an estimated 60% of individuals older than 40,
typically the fair-skinned and blue-eyed easy burners, who tan poorly and have occupations/hobbies that
expose them to lots of sun. Most have at least one actinic keratosis per year. Many have several.
Histologically, AK represents a partial-thickness atypia of the epidermis and, if left untreated, may degenerate into squamous cell carcinoma (SCC). Lesions usually develop as a single, small erythematous plaque, 3–10 mm in diameter, typically located over exposed surfaces, such as nose, forehead, temples, cheeks, ears, bald scalp, forearms, and dorsum of the hands (but also the back, chest, and legs). The lesions have an erythematous base that is usually covered by a scale (hyperkeratosis), often on a background of solar damaged skin, with telangiectasias, elastosis, pigmented lentigines, and multiple erythematous
keratoses. They flare and become more visible during time of immune suppression, acute sun exposure, or
chemotherapy.
One in 20 eventually breaks through into the dermis, becoming invasive and possibly
metastatic. These are typically the most elevated, erythematous, and indurated. Although more common
in older individuals, AK may also affect people in their 20s and 30s, especially fair-skinned redheads and
blonds who do not use sunscreen and live in the “sun belt” (Australia is the nation with the highest AK
prevalence).