What is the pathogenesis of actinic keratoses (AK)?

Updated: Jan 30, 2020
  • Author: Ginard I Henry, MD; Chief Editor: Gregory Gary Caputy, MD, PhD, FICS  more...
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Answer

Answer

Ultraviolet solar damage to epidermal keratinocytes is the most likely origin of this lesion. Other nonsolar sources of epidermal damage that are assumed to cause actinic keratoses are artificial UV light, x-ray irradiation, and exposure to aromatic hydrocarbons. The exposed epidermis experiences a sequence of atrophic, dysplastic, and hyperplastic alterations.

The actinic changes are limited to the interfollicular epidermis; the follicles and the intraepidermal portion of appendageal ducts are spared. The lower layers of the epidermis are the most affected. The stratum corneum undergoes parakeratosis and gives rise to cutaneous horns. The granular layer generally is obliterated except near follicle units. Tonguelike projections of the atypical epidermis may project into the dermis but do not violate the basement membrane. In addition, not infrequently, the basal cells experience some reactive proliferation along with the recruitment of melanocyte activity. These features give actinic keratoses a heavily pigmented appearance and the appearance of a basal cell malignancy. Actinic (solar) changes of the underlying dermis also may occur, and their presence helps in making the diagnosis. [4]


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