Skin problems of aging.

It is not practical to treat diffuse areas of sun damage with liquid nitrogen. Patients with actinic keratoses require painstaking instruction and numerous visits to guide them through a course of 5-fluorouracil (5-Fu) therapy. While basal cell carcinoma rarely metastasizes, its potential for localized destruction and its tendency to recur after therapy should not be underestimated. In certain locations, the tumor does not have a benign clinical course.