Your doctor will likely be able to determine whether you have an actinic keratosis simply by examining your skin. If there's any doubt, he or she may do other tests, such as a skin biopsy. During a skin biopsy, your doctor takes a small sample of your skin for analysis in a lab. A biopsy can usually be done in a doctor's office after a numbing injection.
Even after treatment for actinic keratosis, your doctor will likely suggest that you have your skin checked at least once a year for signs of skin cancer.