What’s Causing This Skin Lesion?

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

There are two categories of skin lesions: primary and secondary.

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

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

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

Acne

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

Learn more about acne in our dedicated article here.

Cold sores

• A cold sore is a red, painful, fluid-filled blister that appears near the 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 often tingles or burns before the cold sore is visible.
• These blisters occur alone or in clusters. Cold sores weep clear yellow fluid before they crust over.
• Blisters may reoccur from stress, menstruation, illness, or sun exposure.

Discover more about the causes, symptoms, and treatments of cold sores here.

Actinic keratosis

• An actinic keratosis is a thick, scaly, or crusty skin patch. It’s typically smaller 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, like the hands, arms, face, scalp, and neck.
• It’s usually pink but can have a brown, tan, or gray base.

Discover more about actinic keratosis.

Allergic eczema

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

Read our dedicated overview of eczema here.

Impetigo

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

Learn all you need to know about impetigo here.

Contact dermatitis

• 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. It appears where your skin touches the irritating substance.
• It also causes blisters that weep, ooze, or become crusty.

Read the full article on contact dermatitis here.

Psoriasis

• Psoriasis causes scaly, silvery, sharply defined skin patches on lighter skin tones.
• On darker skin tones, psoriasis patches may appear light to dark gray, purple, or brown, with silver or lighter scales.
• Psoriasis commonly occurs on the scalp, elbows, knees, and lower back.
• It may be itchy or asymptomatic.

Learn more about the types of psoriasis here.

Chickenpox

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

Read the full article on chickenpox.

Shingles

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

Learn more about shingles and its symptoms here.

Epidermoid cysts

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

Read the full article on epidermoid cysts.

MRSA (staph) infection

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. It has a painful, raised, red pimple that may drain pus.
• The infection is caused by a type of Staphylococcus, or staph, bacteria resistant to many antibiotics.
• The bacteria causes an infection when it enters through a cut or scrape on the skin.
• Powerful antibiotics are needed to treat the infection. MRSA infections can lead to more dangerous conditions, such as cellulitis or blood infection.

Read more about MRSA infections here.

Cellulitis

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

• Cellulitis leaves discolored, painful, swollen skin with or without oozing that spreads quickly.
• It results from 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 indicate a serious infection requiring medical attention.

Read the full article on cellulitis.

Scabies

• 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 4–6 weeks to appear.
• Having scabies increases your risk of impetigo.

Learn more about scabies here.

Boils

• A boil is a 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 buttocks.
• It may rupture and weep fluid.
• The bacterial or fungal infection of a hair follicle or oil gland causes it.

Discover all you need to know about boils here.

Bullae

• A bulla is a clear, watery, fluid-filled blister that’s greater than 1 cm.
• Friction, contact dermatitis, and other skin disorders can cause it.
• If its clear liquid turns milky, there might be an infection.

Read the full article on bullae.

Blisters

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

Learn more about blister symptoms and treatments here.

Nodules

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

Read more about nodules here.

Rash

• A rash is a noticeable change in the color or texture of the skin.
• Many things may cause a rash, including insect bites, allergic reactions, medication side effects, fungal skin infections, bacterial skin infections, infectious diseases, or autoimmune diseases.
• Many rash symptoms can be managed at home, but severe rashes may require urgent medical treatment — especially those that develop with other symptoms, such as fever, pain, dizziness, vomiting, or difficulty breathing.

Read the full article on rashes.

Hives

• 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 more about hives.

Keloids

• 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

• A wart is a raised, rough bump that may be found on the skin or mucous membranes.
• It can occur due to different types of human papillomavirus (HPV).
• A wart may develop singly or in groups.
• It’s contagious and may be transmitted to others.

Learn more about warts here.

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

Other causes and risk factors include:

• systemic infections
• allergic reactions
• hereditary factors
• chronic diseases

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

• Blisters: Blisters are skin lesions filled with a clear fluid.
• Macules: Macules are small spots that are typically brown, red, or white.
• Nodules: Nodules are growths that occur under the skin, such as certain types of cysts.
• Papules: A papule is a raised lesion. Most of them develop with many other papules.
• 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.
• Wheals: A wheal is a skin lesion from 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
• scales
• scars
• skin atrophy
• ulcers

To diagnose a skin lesion, a dermatologist or primary care 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 may take skin samples, perform a biopsy of the affected area, or take a swab from the lesion to send to a lab.

How do you identify lesions?

A lesion is simply an altered or different area of skin. That may be a rash, a sore, bumps, swelling, or other changes in your skin. You may see or feel skin lesions. A dermatologist, a doctor who specializes in skin, can identify the specific type of lesion you have and recommend treatment options.

What are the nine types of primary skin lesions?

Nine of the most common types of primary skin lesions include:

• moles
• acne
• blisters
• macules
• nodules
• papules
• pustules
• rashes
• wheals

How do you get rid of skin lesions?

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

First-line treatments are often topical medications to help treat the inflammation and protect the affected area. Topical or oral medication can also relieve mild symptoms to stop pain, itching, or burning. Surgery may be necessary in cases of severe lesions.

Read this article in Spanish.