What Is a Lesion?

Table of Contents
View All
Table of Contents

A lesion is a mark on the skin that looks or feels different than the surrounding skin. Everything from a blister to a bug bite could be referred to as a lesion. Some lesions are caused by inflammation and disease, while others are simply inherited traits, like birthmarks.

Skin conditions can be challenging to self-diagnose, so regular visits to a dermatologist will offer insight into whether your lesions are a concern. Here's some background on cancerous versus benign lesions, and what you should look out for when checking your skin.

Woman looking down at mole on her shoulder

tomczykbartek / E+ / Getty Images

Types of Skin Lesions

There are numerous markings that can appear on the skin throughout your lifetime. Here's a breakdown of some of the common skin conditions you may have noticed on yourself or seen on others.


A blister is a fluid-filled pocket beneath the skin that may be caused by irritation including burns, allergies, medication, infections, or skin diseases. Blisters are filled with serum (a liquid that protects the underlying skin) or blood.

Protect your skin against blisters by reducing chafing with powder, petroleum jelly, soft bandages, or moisture-wicking clothing. A pair of moisture-wicking socks along with properly sized shoes should help prevent blisters on the feet.

Blisters will heal by themselves in about two weeks, but it's important to avoid irritating the skin further to allow the blister to resolve itself.


Warts are benign skin lesions caused by a viral infection. Flat facial warts, genital warts, and plantar warts (on the feet) are all caused by strains of human papillomavirus (HPV).

Warts are a symptom found anywhere on the skin. Although they typically go away within months, warts can be painful and bothersome. Some warts can be treated at home while others will require intervention at the dermatologist's office.


Moles are a normal occurrence for skin, especially fair skin. Many adults have between 10 to 40 different moles that become darker or lighter with age. Moles are slightly raised and have a round, symmetrical shape.

They're typically brown but may be colorless, tan, or display other tints. You may find moles on your scalp, under your nails, or anywhere on the skin.

Actinic Keratosis

A precancerous skin lesion called actinic keratosis (AK) can be mistaken for a rash, age spots, or a wound, but it's actually a precancerous growth. Some AKs even have a horn-like appearance. AKs tend to develop on sun-damaged skin over a long period of time. On the lips, AKs may look like white patches or sores.

Going to the dermatologist for regular skin checks can help detect AKs before they progress into cancer.


The three most well known and common forms of skin cancer include:

  • Basal cell carcinoma: May seem like a sore that won't heal, a smooth bump that dips in the center sometimes with small, visible blood vessels
  • Squamous cell carcinoma: A defined, thick, red scaly bump on the skin that may bleed or grow large if not removed
  • Melanoma: An aggressive form of skin cancer that can spread to other areas of the body if left untreated

Characteristics of Melanoma

The most serious form of skin cancer is called melanoma. Learning how to recognize the traits of melanoma can help you identify it early. A common way to remember this is with the first five letters of the alphabet:

  • A for asymmetry: Melanoma has an irregular shape where one half does not mirror the other.
  • B for border: The border around melanoma is not well defined.
  • C for color: Melanoma is multicolored with tan, black, brown, and sometimes other colors mixed in.
  • D for diameter: Melanomas can grow quickly and typically are diagnosed once they reach the size of a pencil eraser or larger.
  • E for evolving: Melanoma can seem like a mole that grows and changes rapidly, especially when compared to your other moles and freckles.

Significance of Skin Lesions

Lesions on the skin can range from insignificant to deadly, but most are somewhere in between. If you're dealing with an issue like skin tags, rashes, or blisters, you may want to take action to have it reduced or removed. Luckily, a dermatologist can help address most skin legions through surgical removal, or treatment with prescription creams or medication.

Skin Diagnosis

If you have blisters or hives, your dermatologist will ask questions about your medical history to identify any sensitivities or conditions that may be responsible for your skin reaction. Warts may be biopsied for identification.

Skin lesions that grow rapidly, bleed, itch, stand out, or protrude, tend to get diagnosed faster because they prompt patients to make a dermatology appointment. However, regular skin checks can help your dermatologist catch lesions that seem benign but are in fact precancerous or cancerous.

It's not always easy to discern the difference between a problematic lesion and one that's merely cosmetic, especially for the untrained eye. Visiting the dermatologist as recommended (yearly, or every six months for those with history) is a proactive way to get ahead of potentially-dangerous skin lesions.

Your dermatologist will use a magnifying glass and special light to get a closer look at any new or unusual markings on your skin. Using a small incision (with numbing cream), they may take a small biopsy to send to the lab for analysis.

Treatment Options

To treat a blister, your dermatologist may advise covering it with a bandage and keeping it dry and clean. Popping a blister is generally discouraged, but if it's large and painful your dermatologist can give you instructions on how to sterilize a small needle to allow the fluid to drain.

To have warts removed, your dermatologist may suggest a variety of treatment options. You may be prescribed salicylic acid to apply to damp skin over several weeks.

Liquid nitrogen treatment or laser treatments are move invasive but possible options for wart removal as well.

If your dermatologist decides to biopsy your lesion for further testing, you can expect a phone call with the results within a week or so. For cancerous lesions, you'll be sent to a dermatologic surgeon to fully remove the dangerous cells along with a perimeter to ensure that everything was removed.

Depending on the type of cells and the number of cancerous lesions you have, your dermatologist will likely recommend more frequent skin checks. If further treatment is warranted (in the case of cancer that has spread) you'll be sent to do lab work and see your primary care doctor or an oncologist to collaborate on the next steps.

A Word From Verywell

Taking good care of our skin starts with wearing sunblock and ends with getting regular skin checks at the dermatologist. Even if you have dark skin, it's essential to protect your skin from damage that can lead to cancer. Early detection of skin cancer gives you a chance to have it removed before it grows into a bigger concern.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Harvard Health Publishing. Blisters (overview).

  2. American Academy of Dermatology Association. How to prevent and treat blisters.

  3. American Academy of Family Physicians. Warts.

  4. American Academy of Dermatology Association. Moles: Overview.

  5. American Academy of Dermatology Association. Actinic keratosis: overview.

  6. American Academy of Dermatology Association. Moles: signs and symptoms.

By Anastasia Climan, RDN, CD-N
Anastasia, RDN, CD-N, is a writer and award-winning healthy lifestyle coach who specializes in transforming complex medical concepts into accessible health content.