It’s not difficult to diagnose corns and calluses. No tests are required. A simple visual exam of the skin is usually all that is needed. Your doctor may ask you questions about your job, how much walking and standing you do, and in what activities you participate. If your corn or callus is on your foot, your doctor may ask you to walk to check your posture and the way you walk, ask about your footwear and ask how you take care of your feet.