Skin Lesion: What It Means and When to Get It Checked

What a skin lesion means

"Lesion" simply means an area of abnormal tissue. Doctors use the word because it describes what they see without assuming a cause. A pimple, a mole, a wart, a burn blister and a skin cancer are all skin lesions.

Dermatologists describe lesions in a standard way so that others can picture them: size, color, shape, surface, number, and where they are on the body. That description narrows down the cause.

Types of skin lesions

Primary lesions

Primary lesions are the first change the disease produces.

Secondary lesions

Secondary lesions develop from primary ones or from scratching and healing: scale (flaking), crust (dried fluid or blood, a scab), erosion (loss of the top layer), ulcer (deeper loss of skin), fissure (crack), lichenification (thick, leathery skin from rubbing) and scar.

Common harmless skin lesions

• Moles: brown, even-colored spots that appear mainly in childhood and young adulthood and stay stable.
• Seborrheic keratoses: waxy, "stuck-on" brown or black growths that become common after 40. They are harmless but can look worrying.
• Skin tags: small, soft flaps of skin on the neck, armpits and groin.
• Cherry angiomas: small, bright red dome-shaped spots made of blood vessels.
• Epidermoid cysts: round lumps under the skin, often with a central pore, that can become inflamed.
• Dermatofibromas: firm, small brown bumps, often on the legs, that dimple when pinched.
• Lipomas: soft, rubbery, movable lumps of fat under the skin.

Lesions caused by infection or inflammation

• Bacterial: impetigo (honey-colored crusts), boils and cellulitis (spreading red, warm skin).
• Viral: warts, cold sores, molluscum contagiosum, chickenpox and shingles.
• Fungal: ringworm, with ring-shaped scaly patches.
• Inflammatory: eczema, psoriasis, acne and hives. These are usually widespread or recurring rather than a single spot.

Skin lesions that may be cancer or precancer

Actinic keratosis

Actinic keratoses are rough, sandpaper-like scaly patches on sun-damaged skin such as the face, scalp, ears and backs of the hands. They are precancerous: a small proportion become squamous cell carcinoma.

Basal cell carcinoma

The most common skin cancer. Basal cell carcinoma usually looks like a pearly or shiny pink bump with tiny visible blood vessels, or a sore that bleeds, scabs, and never fully heals. It grows slowly and rarely spreads, but can damage nearby tissue.

Squamous cell carcinoma

A firm, scaly or crusted red bump or a non-healing sore, often on sun-exposed skin, lips or ears. Squamous cell carcinoma can spread if left untreated, especially on the lips and ears and in people with weakened immune systems.

Melanoma

Melanoma is less common but more dangerous. Use the ABCDE checklist on any mole:

• Asymmetry: one half does not match the other
• Border: ragged, notched or blurred edges
• Color: several shades of brown or black, or patches of red, white or blue
• Diameter: larger than 6 mm (a pencil eraser), though melanomas can be smaller
• Evolving: any change in size, shape, color, height, or new itching or bleeding

When to worry about a skin lesion

See a doctor about a skin lesion that:

• is new and you are over 30, or looks different from your other moles
• is changing in any way over weeks to months
• bleeds without injury, crusts repeatedly, or has not healed in 4 weeks
• is a firm, growing lump
• is a dark streak under a nail that is not from an injury

People with fair skin, many moles, a history of sunburn or tanning beds, a family history of melanoma, or a weakened immune system (for example after an organ transplant) should check their skin monthly and have regular skin exams.

How doctors diagnose a skin lesion

1. History: how long it has been there, whether it has changed, symptoms such as itch or bleeding, sun exposure and family history.
2. Full skin examination: comparing the lesion with your other spots.
3. Dermatoscopy: a handheld magnifying light that shows patterns invisible to the naked eye. It helps separate harmless lesions from melanoma.
4. Biopsy: a shave, punch or full removal of the lesion under local anesthetic. A pathologist examines it under a microscope. This is the only way to confirm cancer.
5. Swabs or scrapings: for suspected infection.

Treatment

Treatment depends entirely on the cause:

• Harmless lesions need no treatment, but can be removed for comfort or appearance by freezing, shaving or cutting out.
• Actinic keratoses: freezing with liquid nitrogen, prescription creams or light-based therapy.
• Skin cancers: surgical removal is the main treatment. Mohs surgery is used for some facial cancers to save healthy tissue. Melanoma may need wider removal and lymph node checks.
• Infections: antibiotic, antiviral or antifungal treatment.
• Inflammatory lesions: creams, moisturizers and avoiding triggers.

Do not try to cut off, burn or freeze a lesion yourself with home kits. This can cause scarring and infection, and can destroy a cancer partly so that it is missed.

Preventing skin lesions from sun damage

• Use broad-spectrum sunscreen of SPF 30 or higher, and reapply every 2 hours outdoors.
• Seek shade between 10 a.m. and 4 p.m., and wear a hat and sun-protective clothing.
• Avoid tanning beds.
• Check your skin once a month, including your back and scalp, with a mirror or a partner.

Frequently asked questions

What does skin lesion mean?

A skin lesion is any area of skin that differs from the surrounding skin in color, texture, shape or thickness. It is a general description, not a diagnosis. Moles, warts, rashes, blisters, cysts, ulcers and skin cancers are all examples of skin lesions.

Are skin lesions cancerous?

Most are not. The vast majority are harmless moles, keratoses, cysts, tags or infections. A lesion is more likely to need checking if it is new, changing, bleeding, crusting, not healing within 4 weeks, or looks different from your other spots.

What does a cancerous skin lesion look like?

Basal cell carcinoma often looks like a pearly pink bump or a sore that will not heal. Squamous cell carcinoma looks like a firm, scaly or crusted red bump. Melanoma is usually a mole with uneven shape, ragged border, multiple colors, larger size or recent change.

What is the difference between a primary and a secondary skin lesion?

A primary lesion is the first change caused by a disease, such as a papule, blister or patch. A secondary lesion develops later from the primary one or from scratching, healing or infection. Scales, crusts, ulcers, cracks and scars are secondary lesions.

How are skin lesions removed?

Doctors remove lesions by freezing with liquid nitrogen, shaving them off, cutting them out with stitches, or scraping and cauterizing. Suspicious lesions are sent to a lab for testing. Removal is done under local anesthetic and usually takes minutes in the office.