Solar keratoses and their relationship to non-melanoma skin cancers.

Solar keratoses belong to the list of clinically invisible dermatoses, as the loss of their horny layer may create the illusion that they have disappeared, and numerous subclinical lesions can be highlighted by 5-fluorouracil therapy. Solar keratoses are recognized as potential precursors for squamous cell carcinoma. However, basal cell carcinoma (BCC) may develop in a soft type of solar keratoses as a consequence of migration of pluripotential adnexal epithelial cells in reparative response to trauma, particularly in areas rich in adnexal structures, such as the face. These intraepithelial resident adnexal cells may result in the development of BCC following chronic solar exposure and damage.