First of all, what is a skin lesion?
A skin lesion is a broad term that refers to any abnormality on your skin. Medical dictionaries define skin lesion as a superficial growth or patch of the skin that does not resemble the area surrounding it. A skin lesion can be a rash, mole, wart, cyst, blister, bump, discoloration, or other change that you may notice on your skin.
A skin lesion can be a result of a simple scrape or cut or as severe as a pre-cancerous mole or mark. While the spectrum of lesions ranges significantly, there are some general categories you can use to identify yours.
What types of skin lesions are there?
There are two types of skin lesions: primary and secondary. Primary skin lesions are changes in color or texture that are generally present at birth or acquired over time, such as a birthmark or an age spot. Secondary skin lesions are a progression of primary skin lesions. They are changes to the original lesion that result from a natural evolution of the lesion or a person scratching or aggravating the lesion.
Primary skin lesions:
A macule is a distinct discoloration of the skin that is flat and smaller than 1 centimeter in diameter. It does not cause a change in skin texture or thickness. Macules are noticed visually.
A papule is a raised skin area with no visible fluid and sized up to 1 centimeter in diameter. They have distinct borders and come in a variety of shapes.
A nodule is an elevated bump on the skin that is larger than a papule (greater than 1 centimeter in diameter). It may occur in all layers of the skin including the epidermis, dermis and subcutaneous tissue.
A tumor is a solid mass on the skin or subcutaneous tissue (under the skin). It is firm and usually larger than 2 centimeters.
A plaque is a flat-topped, raised lesion larger than 1 centimeter. It is often red, scaly and itchy. Plaques are typically found on the scalp, elbows, and knees.
A vesicle is a raised bump less than 1 centimeter in diameter filled with air or clear liquid.
Bullae are fluid-filled sacs that form when fluid is trapped under a thin layer of skin. They are similar to blisters and vesicles except that bullae have a diameter larger than 1 centimeter.
A pustule is a small bump on the skin that contains pus. They can be infected but not always, as in the case of pustular psoriasis.
A wheal is a red, swollen mark that is often itchy and changes shape. They usually occur in response to a stimulus like a bug bite or food allergies. They are also known as welts or hives.
Burrows are tunnels formed in the skin that appear as linear marks. They are a result of an infestation of the skin by parasites such as scabietic mites.
Telangiectasia is a condition where blood vessels near the surface of the skin are dilated and cause threadlike lines or patterns on the skin. They are sometimes called spider veins. It can be caused by a variety of conditions such as rosacea or liver disease.