A skin lesion is a part of the skin that has an abnormal growth or appearance compared to the skin around it.

Two categories of skin lesions exist: primary and secondary.

Primary skin lesions are abnormal skin conditions present at birth or acquired over a person’s lifetime.

Secondary skin lesions are the result of irritated or manipulated primary skin lesions. For example, if someone scratches a mole until it bleeds, the resulting lesion, a crust, is now a secondary skin lesion.

Many conditions can cause different types of skin lesions. Here are 21 possible causes and types.

Warning: Graphic images ahead.

Acne

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  • Acne is commonly located on the face, neck, shoulders, chest, and upper back.
  • Breakouts are composed of blackheads, whiteheads, pimples, or deep, painful cysts and nodules.
  • If it’s left untreated, it may leave scars or darken the skin.

Read the full article on acne.

Cold sores

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  • A cold sore is a red, painful, fluid-filled blister that appears near the mouth and lips.
  • The viruses herpes simplex 1 (HSV-1) and herpes simplex 2 (HSV-2) cause genital lesions as well as these types of oral lesions.
  • The affected area will often tingle or burn before the cold sore is visible.
  • These blisters occur alone or in clusters, weeping clear yellow fluid before they crust over.
  • Blisters may reoccur in response to stress, menstruation, illness, or sun exposure.

Read the full article on cold sores.

Actinic keratosis

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  • An actinic keratosis is a thick, scaly, or crusty skin patch that’s typically less than 2 centimeters (cm), or about the size of a pencil eraser.
  • It appears on parts of the body that receive a lot of sun exposure (the hands, arms, face, scalp, and neck).
  • It’s usually pink in color but can have a brown, tan, or gray base.

Read the full article on actinic keratosis.

Allergic eczema

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  • Allergic eczema leaves the skin itchy, red, scaly, or raw.
  • It’s often found on the hands and forearms and may resemble a burn.
  • It also causes blisters that weep, ooze, or become crusty.

Read the full article on allergic eczema.

Impetigo

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  • Impetigo causes an irritating rash and fluid-filled blisters that pop easily and form a honey-colored crust.
  • The rash is often located in the area around the mouth, chin, and nose.
  • The condition is common in babies and children.

Read the full article on impetigo.

Contact dermatitis

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  • Contact dermatitis causes itchy, red, scaly, or raw skin.
  • It appears hours to days after contact with an allergen.
  • A contact dermatitis rash has visible borders and appears where your skin touched the irritating substance.
  • It also causes blisters that weep, ooze, or become crusty.

Read the full article on contact dermatitis.

Psoriasis

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  • Psoriasis causes scaly, silvery, sharply defined skin patches.
  • It’s commonly located on the scalp, elbows, knees, and lower back.
  • It may be itchy or asymptomatic.

Read the full article on psoriasis.

Chickenpox

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  • Chickenpox leaves clusters of itchy, red, fluid-filled blisters in various stages of healing all over the body.
  • A chickenpox rash is accompanied by fever, body aches, sore throat, and loss of appetite.
  • Chickenpox remains contagious until all the blisters have crusted over.

Read the full article on chickenpox.

Shingles

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  • Shingles causes a very painful rash that may burn, tingle, or itch, even if there are no blisters present.
  • A shingles rash emerges in a linear stripe pattern that appears most commonly on the torso, but may occur on other parts of the body, including the face.
  • The rash comprises clusters of fluid-filled blisters that break easily and weep fluid.
  • The rash may be accompanied by low fever, chills, headache, or fatigue.

Read the full article on shingles.

Epidermoid cysts

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  • Epidermoid cysts are found on the face, neck, or torso.
  • Large cysts may cause pressure and pain.
  • They’re noncancerous, filled with the protein keratin, and very slow growing.
  • They’re sometimes mistaken for sebaceous cysts, which are filled with sebum.

Read the full article on epidermoid cysts.

MRSA (staph) infection

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This condition is considered a medical emergency. Urgent care may be required.

  • The methicillin-resistant Staphylococcus aureus (MRSA) skin infection often looks like a spider bite, with a painful, raised, red pimple that may drain pus.
  • The infection is caused by a type of Staphylococcus, or staph, bacteria that’s resistant to many different antibiotics.
  • The bacteria causes an infection when it enters through a cut or scrape on the skin.
  • The infection needs to be treated with powerful antibiotics and can lead to more dangerous conditions, such as cellulitis or blood infection.

Read the full article on MRSA infection.

Cellulitis

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This condition is considered a medical emergency. Urgent care may be required.

  • Cellulitis leaves red, painful, swollen skin with or without oozing that spreads quickly.
  • It’s caused by bacteria or fungi entering through a crack or cut in the skin.
  • The skin may also be hot and tender to the touch.
  • Fever, chills, and red streaking from a rash might be a sign of serious infection requiring medical attention.

Read the full article on cellulitis.

Scabies

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  • Scabies causes an extremely itchy rash that may be pimply, made up of tiny blisters, or scaly.
  • It also causes raised white or flesh-toned lines.
  • Symptoms may take 4 to 6 weeks to appear.
  • Having scabies increases your risk of impetigo.

Read the full article on scabies.

Boils

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  • A boil is a red, painful, raised bump with a yellow or white center.
  • It can appear anywhere on the body, but is most common on the face, neck, armpit, and buttock.
  • It may rupture and weep fluid.
  • It’s caused by the bacterial or fungal infection of a hair follicle or oil gland.

Read the full article on boils.

Bullae

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  • A bulla is a clear, watery, fluid-filled blister that’s greater than 1 cm in size.
  • It can be caused by friction, contact dermatitis, and other skin disorders.
  • If clear liquid turns milky, there might be an infection.

Read the full article on bullae.

Blisters

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  • A blister is characterized by a watery, clear, fluid-filled area on the skin.
  • It may be smaller than 1 cm (vesicle) or larger than 1 cm (bulla) and occur alone or in groups.
  • It can be found anywhere on the body.

Read the full article on blisters.

Nodules

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  • A nodule is a small to medium growth that may be filled with tissue, fluid, or both.
  • It’s usually wider than a pimple and may look like a firm, smooth elevation under the skin.
  • It’s usually harmless, but may cause discomfort if it presses on other structures.
  • It may also be located deep inside the body where you can’t see or feel it.

Read the full article on nodules.

Rash

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This condition is considered a medical emergency. Urgent care may be required.

  • A rash is defined as a noticeable change in the color or texture of the skin.
  • It may be caused by many things, including insect bites, allergic reactions, medication side effects, fungal skin infection, bacterial skin infection, infectious disease, or autoimmune disease.
  • Many rash symptoms can be managed at home, but severe rashes may require urgent medical treatment (especially those seen in combination with other symptoms, such as fever, pain, dizziness, vomiting, or difficulty breathing).

Read the full article on rash.

Hives

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  • Hives are itchy, raised welts that occur after exposure to an allergen.
  • They’re red, warm, and mildly painful to the touch.
  • They can be small, round, and ring-shaped or large and randomly shaped.

Read the full article on hives.

Keloids

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  • A keloid is a lumpy or rigid area of skin that may be painful or itchy.
  • The area is flesh-colored, pink, or red.
  • The symptoms occur at the site of a previous skin injury.

Read the full article on keloids.

Warts

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  • A wart is a raised, rough bump that may be found on the skin or mucous membranes.
  • It’s caused by many different types of a virus called human papillomavirus (HPV).
  • A wart may occur singly or in groups.
  • It’s contagious and may be passed to others.

Read the full article on warts.

The most common cause of a skin lesion is an infection on or in the skin.

One example is a wart. The human papillomavirus (HPV), which causes warts, is passed from one person to another through direct skin-to-skin contact. The herpes simplex virus, which causes both cold sores and genital herpes, is also passed through direct contact.

A systemic infection, which is an infection that occurs throughout your body, can cause skin lesions all over your body. Examples include chickenpox and shingles. MRSA and cellulitis are two potentially life threatening infections that involve skin lesions.

Some skin lesions, such as moles and freckles, are hereditary. Birthmarks are lesions that exist at the time of birth.

Others can be the result of an allergic reaction, such as allergic eczema and contact dermatitis. Some conditions, such as poor circulation or diabetes, cause skin sensitivity that can lead to lesions.

Birthmarks are primary skin lesions, as are moles and acne. Other types include the following.

Blisters

Blisters are skin lesions filled with a clear fluid. Small blisters measuring less than 1 cm in size are also called vesicles. Larger blisters are called bullae or, simply, blisters.

These lesions can be the result of:

Macules

Macules are small spots that are typically brown, red, or white. They’re usually about 1 cm in diameter. Examples include freckles and flat moles.

Nodules

A nodule is a term used to describe growths that occur under the skin, such as certain types of cysts. Nodules are typically under 2 cm. If the nodule becomes big enough, it can affect the overlying skin too.

Papules

A papule is a raised lesion, and most of them develop with many other papules.

A patch of papules or nodules is called a plaque. Plaques are common in people with psoriasis.

Pustules

Pustules are small lesions filled with pus. They’re typically the result of acne, boils, or impetigo.

Rashes

Rashes are lesions that cover small or large areas of skin. They can be caused by an allergic reaction. A common allergic reaction rash occurs when a person touches poison ivy.

Wheals

A wheal is a skin lesion caused by an allergic reaction. Hives are an example of wheals.

When primary skin lesions are irritated, they can develop into secondary skin lesions. The most common secondary skin lesions include:

Crusts

A crust, or a scab, is created when dried blood forms over a scratched and irritated skin lesion.

Scales

Scales, such as those caused by actinic keratosis, are patches of skin cells that build up and then flake off the skin.

Scars

Some scratches, cuts, and scrapes will leave scars that aren’t replaced with healthy, normal skin. Instead, the skin returns as a thick, raised scar. This scar is called a keloid.

Skin atrophy

Skin atrophy occurs when areas of your skin become thin and wrinkled from poor circulation or overuse of topical steroids.

Ulcers

Ulcers are typically caused by a bacterial infection or physical trauma. They’re often accompanied by poor circulation.

Some skin lesions are hereditary. People with family members who have moles or freckles are more likely to develop those two types of lesions.

People with allergies may also be more likely to develop skin lesions related to their allergy.

People diagnosed with an autoimmune diseases such as psoriasis will continue to be at risk of developing skin lesions throughout their lives.

In order to diagnose a skin lesion, a dermatologist or doctor will conduct a full physical exam. This will include observing the skin lesion and asking for a full account of all symptoms.

To confirm a diagnosis, they make take skin samples, perform a biopsy of the affected area, or take a swab from the lesion to send to a lab.

If you don’t already have a dermatologist, you can browse doctors in your area through the Healthline FindCare tool.

Treatment is based on the underlying cause or causes of the skin lesions. A doctor will take into account the type of lesion, your personal health history, and any treatments previously attempted.

Medications

First-line treatments are often topical medications to help treat the inflammation and protect the affected area. Topical medication can also provide mild symptom relief to stop pain, itching, or burning caused by the skin lesion.

If your skin lesions are the result of a systemic infection, such as chickenpox or shingles, you may be prescribed oral medications to help ease the symptoms of the disease, including skin lesions.

Surgery

Infected skin lesions are typically pierced and drained to provide treatment and relief.

Suspicious-looking moles that have been changing over time may need to be removed surgically.

A type of birthmark called hemangioma results from malformed blood vessels. Laser surgery is often used to remove this type of birthmark.

Home care

Some skin lesions are very itchy and uncomfortable. You may want to try home remedies for relief.

Oatmeal baths or lotions can provide relief from itching or burning caused by certain skin lesions.

If chafing is causing contact dermatitis in places where the skin rubs against itself or a piece of clothing, absorbent powders or protective balms can reduce friction and prevent additional skin lesions from developing.