What Are the Types of Skin Lesions?

What is a skin lesion?

A skin lesion is an abnormal growth or rash.
A skin lesion is an abnormal growth or rash.

A skin lesion is an abnormal growth or rash on the skin as compared to normal skin. There are two main categories of skin lesions: primary and secondary lesions.

  • Primary skin lesions are abnormal skin conditions that may be present at birth or acquired later.
  • Secondary skin lesions are a result of irritated or manipulated primary skin lesions. For example, a crust that forms following a scratch or an infected allergic wheal.

Types of primary skin lesions

Primary lesions may be present at birth or acquired later in a person’s life. The most common primary skin lesions include

  • Birthmarks: These are the most common primary skin lesions. They  include moles, port-wine stains, nevi, etc.
  • Blisters: Blisters are skin lesions that are less than half a centimeter in diameter and filled with clear fluid. Small blisters are called vesicles and larger ones are called the bullae. Blisters may be caused by burns (including sunburns), viral infections (herpes zoster), friction due to shoes or clothes, insect bites, drug reactions, etc.
  • Macules: Macules are flat skin lesions. They are small (less than one centimeter in diameter) and may be brownish or reddish. Freckles and flat moles are examples of macules. A macular rash is commonly seen in measles.
  • Nodules: Nodules are soft or firm, raised skin lesions that are less than two centimeters in diameter. The nodules are seen in certain diseases such as neurofibromatosis and leprosy.
  • Papule: Papules are raised lesions and usually develop with other papules. A patch of papules or nodules is called a plaque. Plaques are commonly seen in psoriasis. Papules may be seen in viral infections, such as measles, or may occur due to mosquito bites.
  • Pustule: Pustules are pus-filled lesions. Boils and abscesses are examples of pustules.
  • Wheals: Wheals are swollen, raised bumps or plaques that appear suddenly on the skin. They are mostly caused by an allergic reaction. For example, hives (also called urticaria), insect bites, etc.

Types of secondary skin lesions

Secondary skin lesions, which get inflamed and irritated, develop after primary skin lesions or due to an injury. The most common secondary skin lesions include

  • Crust: A crust or a scab is a type of skin lesion that forms over a scratched, injured or irritated primary skin lesion. It is formed from the dried secretions over the skin.
  • Ulcer: Ulcers are a break in the continuity of the skin or mucosa. Skin ulcers are caused by an infection or trauma. Poor blood circulation, diabetes, smoking and/or bedridden status increase the risk of ulcers.
  • Scales: Scales are patches of skin cells that build up and flake off the skin. Patches are often seen in psoriasis and cause bleeding when they are removed.
  • Scar: Injuries, such as scratches, cuts and scrapes, can leave scars. Some scars may be thick and raised. These may cause itching or oozing and appear reddish or brownish. These are called keloids.
  • Skin atrophy: Skin atrophy occurs when areas of the skin become thin and wrinkled. This could occur due to the frequent use of steroid creams, radiation therapy or poor blood circulation.


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