Examples of benign tumors are seborrheic keratosis , keratoacanthoma , and the often premalignant actinic keratosis . This is the most frequent type of skin cancer and tends to occur in older persons. Lesions almost always occur in sun exposed regions. Treatment is necessary due to the localized damage caused by this cancer. This cancer is usually smooth with a pearly border and may be pigmented with a ulceration in the center of the lesion.
Treatment is by surgical removal, freezing or local chemotherapy.
This cancer can affect both the skin and mucous membranes. It most often occurs in sun exposed or burned areas. Tar deravatives such as those in tobacco smoke or other carcinogens and chronic radiation exposure are predisposing factors. Immunosupression in transplant patients makes them at greater risk of developing these lesions. The lesions appear as rough scaly nodules that can ulcerate and metastsize.