What causes skin lesions?

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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.  Skin lesions can be a rash, mole, wart, cyst, blister, bump, discoloration, or other changes that you may notice on your skin. Skin lesions can also 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 age spots. 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.

The common types of primary skin lesions are:

  • Blisters: also called vesicles; these are small lesions filled with a clear fluid. Vesicles can be the result of sunburns, steam burns, insect bites, friction from shoes or clothes and viral infections.
  • Macule: freckles and flat moles. Macules are small spots that are typically brown, red or white. They are usually about one centimeter in diameter.
  • Nodule: a solid, raised skin lesion. Most nodules are more than two centimeters in diameter.
  • Papule: a lesion that is rough in texture. Most papules develop with many other papules. A patch of papules is called a plaque. Plaques usually appear in people with psoriasis.
  • Pustule: small lesion filled with pus. Pustules are typically the result of acne, boils or impetigo.
  • Rash: lesions that cover small or large areas of skin. An allergic reaction can typically cause them. Usually, an allergic reaction rash occurs when a person touches poison ivy.
  • Wheals: skin lesions caused by an allergic reaction. Hives are an example of wheals.

The common types of secondary skin lesions are:

  • Crusts: a crust, or a scab, is created when dried blood forms over a scratched and irritated skin lesion.
  • Ulcers: typically caused by bacterial infection or physical trauma.
  • Scale: patches of skin cells that build up and then fall off the skin.
  • Scars: some scratches, cuts, and scrapes will leave scars that are not replaced with healthy skin. Instead, the skin returns as a thick, raised scar. This scar is called a keloid.
  • Skin atrophy: areas of your skin that become thin and wrinkled from overuse of topical steroids or antibiotic creams.

So what causes skin lesions?

What causes skin lesions can range widely, depending on the specific type of lesion you have. The most common cause of skin lesions is an infection of the skin by bacteria, viruses, fungi or parasites transferred by touch or through the air. Warts and chickenpox are some examples of possible infections. Other types of lesions can be caused by allergic sensitivities or health conditions, such as diabetes or poor circulation. Skin lesions can also be a result of genetic predispositions (inherited). For example, some people are more likely to develop moles and freckles than others.

You should consult your doctor if you notice any suspicious skin lesions on your skin. A doctor will examine the lesion, looking for distinguishing characteristics and checking your past medical history. Doctors often also take a scrape or swab of the lesion to investigate the potential cause of infection.

Types of skin moles and how to know if they’re safe

Is my mole cancerous?

Cancerous lesions often appear in the form of a mole. Understanding the difference between a normal mole and a potentially cancerous mole is key to detecting melanoma and other skin cancers early.

A normal or common mole usually:

A normal mole
A normal mole
  • has neat edges
  • is smooth or dome-shaped
  • is around ¼ inch (6 mm) in diameter
  • preserves the same shape, size or color over time.

It’s important to make an archive of your moles so that you can recognize any changes over time. Understanding what’s normal for your body is the best way to detect early skin cancer symptoms.

Scan your skin with SkinVision for early signs of skin cancer. Download it now.

Warning signs that a mole may be cancerous

Do you suspect a skin lesion as not normal? Look for these indicators to identify whether a skin spot is potentially cancerous:

  • A change in size (getting larger)
  • A change in shape (especially with irregular edges)
  • A change in color (especially getting darker or exhibiting multiple shades)
  • A loss of symmetry (common moles are usually perfectly round or oval and symmetrical)
  • Itchiness, pain or bleeding (maybe even forming a scab)
  • Crustiness
  • Inflammation
  • Exhibiting three different shades of brown or black
  • A change in elevation (thickening or raising of a flat mole)

Skin cancer pictures

If at any time you feel uncomfortable about a skin spot, consult your doctor.

Learn the health of your skin
What causes skin lesions? 1
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"The melanoma could have been on my arm for years"
Andrew Bartlett
United Kingdom
"The melanoma could have been on my arm for years"
Andrew Bartlett
United Kingdom

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