What is a skin lesion? A skin lesion is any change in the normal character of your skin. A skin lesion may occur on any part of your body and cover a tiny or large area. Skin lesions can be singular or multiple, confined to one specific area of your body or distributed widely. Skin lesions include rash, cysts, pus-filled sacs, blisters, swelling, discolorations, bumps, hardening, or any other change in or on your skin. Skin lesions may result from a wide range of causes, as harmless as a small scrape or as serious as skin cancer. There are many common causes of skin lesions. For example, injury can cause a bruise, scrape or cut. Teenagers may have skin lesions from acne, while aging may bring freckles, moles and discoloration. A number of infectious diseases cause rashes, and allergic reactions may be accompanied by itchy hives or rashes. Skin changes can also occur with chronic conditions, such as diabetes or autoimmune disorders. Skin lesions, such as boils and carbuncles, may also be caused by local infections of the skin or hair follicles. Skin cancer and precancerous changes in the skin are more serious causes of skin lesions. These lesions most commonly appear on areas of your body that have been exposed to sun, including your face, arms and hands. Because skin lesions can arise from numerous conditions, which may be harmless or serious, contact your health care provider if you have a new skin lesion that causes you concern or lasts for more than a day or two, or if your child has a skin lesion. Skin lesions are usually mild, but in some cases they can be a sign of a serious condition. Seek immediate medical care (call 911) if you have difficulty breathing or feel your throat swelling, experience fainting or loss of consciousness, have small red dots or larger bruises that appear immediately after taking a new medication, or if you or your child develops a rash along with a fever. Seek prompt medical care if you discover a mole or dark skin lesion that has changed significantly, or if you have a skin lesion that is persistent or causes you concern.