However, in most conditions that have been designated clinically as precancerous, malignant changes are observed only occasionally. In the two years preceding therapy, the patients had a total of 121 tumors. During the two years of isotretinoin treatment, only 25 new tumors developed. All patients experienced mucocutaneous side effects, and some had abnormal liver function tests, hypertriglyceridemia, and skeletal changes. Single or multiple lesions develop on areas exposed to the sun, such as the face, the backs of the hands, the forearms, the neck, and balding scalp.
Actinic cheilitis denotes scaly or crusted patches of precancer on the vermilion of the lips.
In actinic keratosis, lesions are round or irregularly shaped, erythematous or tan plaques with an adherent scaly or rough surface. They range in size from several millimeters to 1 cm or more. Locally invasive lesions have been reported to develop in 12 percent of patients with actinic keratoses. Signs that an actinic keratosis has become malignant are elevation, ulceration or inflammation, and recent enlargement, usually to a diameter greater than 1 cm. On histologic examination, the epidermis may be thickened or atrophic.