What Is Melanoma?

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Melanoma is a skin cancer that arises from a skin cell called a melanocyte, which makes a the pigment (melanin) that gives your skin its color. Melanoma can appear in different ways, most commonly as a new spot on the skin or as an already existing mole that changes in color, size, or shape. While considered the most dangerous type of skin cancer because of its ability to rapidly spread throughout the body, melanoma is generally very treatable if found early.

 Verywell / Alexandra Gordon

Melanoma Types and Symptoms

Distinguishing between a cancerous and a normal mole can be challenging, even for healthcare providers. This is why any new, changed, or out of place skin spot should be checked out by a dermatologist.

Potential signs and symptoms of melanoma include:

  • Itching or other skin sensation like tenderness or pain
  • Sore on the skin that does not heal
  • Bleeding or oozing from a mole
  • Change in the surface of a mole like a lump or bump
  • Spread of pigment from the border of a mole into the surrounding skin
  • Redness or swelling surrounding a mole

But this list is limited. How melanoma presents also has a lot to do with which of the four main subtypes it is, as each have their own characteristics. Any mole that has a diameter that is the same or larger than the diameter of a pencil eraser should be evaluated.

Superficial Spreading

This is the most common subtype of melanoma in people with fair skin. It usually begins as a brown or black spot that is asymmetric, has irregular borders, exhibits changes in color.

This photo contains content that some people may find graphic or disturbing.

Melanoma in situ
Early melanoma. DermNet / CC BY-NC-ND

Nodular Melanoma

After superficial spreading melanoma, nodular melanoma is the next most common type of melanoma in fair-skinned individuals. Instead of growing outward, this melanoma grows vertically (deep into the skin).

Nodular melanoma usually begins as a dark or lightly colored (pink hue) raised spot.

Lentigo Maligna

This subtype of melanoma is most common in chronically sun-damaged areas of skins in older individuals. Lentigo maligna typically starts as an irregular-shaped tan or brown spot that grows slowly over the years to form a larger spot that becomes asymmetric and/or develops color changes or raised areas.

Acral Lentiginous

This subtype accounts for less than 5% of all melanomas. However, it is the most common type among dark-skin individuals.

Acral lentiginous melanoma usually appears on the palms of the hands or soles of the feet as an irregularly-shaped growth or an elevated, thickened patch that is changing in color or size. It may also appear underneath a fingernail or toenail as a brown or black streak or band.

If melanoma grows large and spreads to other regions of the body, it may cause symptoms related to that spread. For example, a melanoma that has spread to the liver may cause jaundice, a yellowish discoloration of the skin.
Cancers that have spread may also cause systemic symptoms such as fatigue, unintentional weight loss, and weakness.


Melanoma develops when DNA changes occur within melanocytes. These DNA changes cause once normal, healthy skin cells to turn into cancer cells that grow uncontrollably.

Ultraviolet (UV) radiation from natural or artificial sources, including tanning beds and sun lamps, is a major cause of melanoma, as UV rays can directly damage the DNA within skin cells.

Besides UV exposure, other risk factors that increase your risk for developing melanoma include:

  • Having fair skin, naturally red or blond hair, and/or blue or green eye color
  • A family or personal history of melanoma
  • Having a large number of moles (over 50)
  • Older age
  • Being male
  • Having many freckles or developing freckles easily
  • A history of sunburns
  • Having a disease or taking a medication that weakens your immune system

Bear in mind, people with dark skin can get melanoma, and due to similarities in color between the skin and the mole, these cases can be more difficult to diagnose. In addition, people without any risk factors, or who have had very little sun exposure or wear sunscreen, can get melanoma.


The ABCDE Rule of Melanoma


Diagnosing skin cancer typically begins with a medical history and skin exam by a dermatologist. Your healthcare provider will access your risk factors for skin cancer, such as your history of sunburns, as well as your family history for melanoma.

In assessing for potential melanoma, they will also consider other possible conditions. For example, sometimes acral lentiginous can mimic benign (noncancerous conditions) like warts, ingrown toenails, calluses, or athlete's foot.

Skin Examination

During the skin exam, the healthcare provider will carefully examine your skin for suspicious marks or spots, noting their size, shape, color, and texture. He may use a tool called a dermatoscope, which is an instrument that contains a light and a magnifying lens to better visualize skin spots.


To help sort out normal moles from melanoma, a mnemonic—the ABCDE rule of melanoma—is often utilized by dermatologists during skin exams. Patients can also use this as a guide as to when to see a dermatologist as soon as possible.

The ABCDE rule spotlights the characteristics by which you assess a suspicious mole:

  • Asymmetry: In the case of skin cancer, spots will not look the same on both side.
  • Border: A mole or spot with blurry and/or jagged edges would be considered concerning.
  • Color: Melanomas tend to be "more colorful" than regular moles. Different colors or shades in the same mole are also of concern.
  • Diameter: Melanomas tend to be larger than normal moles (but certainly not always).
  • Evolution: This refers to any change in a mole (e.g., texture, degree of elevation, size, color, etc.) 

Another potential warning sign of melanoma is a mole that stands out from other moles, due to its different appearance—even if it does not fulfill the above ABCDE criteria. This is referred to as the "ugly duckling" sign.

Skin Biopsy

If there is any suspicion for melanoma or any other type of skin cancer or abnormality, a skin biopsy will be performed. With a skin biopsy, a dermatologist removes a sample of the suspicious "spot," which can then be examined under a microscope for cancer cells by a type of healthcare provider called a dermatopathologist.

Sometimes, to confirm the diagnosis of melanoma or to further evaluate the genetic pattern of the melanoma cells (which can affect melanoma treatment and prognosis), a dermatopathologist will perform additional tests on the biopsy sample in the lab.

Imaging Tests

If the biopsy results show the presence of melanoma, imaging tests, such as a chest X-ray or computed tomography (CT) scan may be performed to determine if and how far the disease has spread.


There are currently five methods of treating melanoma—surgery, immunotherapy, targeted therapy, chemotherapy, or radiation therapy. Treatment depends largely on how deeply the melamona has grown, whether the cancer has spread to other parts of the body, and your overall health.


All melanomas (except that are known to have metastasized already) will be surgically removed along with a wide margin of normal skin. The procedure might also include a biopsy of a nearby lymph node to evaluate whether the melanoma has spread.

Advanced Melanoma

If the disease is more advanced, immunotherapies, which are drugs that stimulate a person's own immune system to attack the cancer, or targeted therapies, which are drugs that attack melanoma cells containing specific gene mutations, may be recommended.

Chemotherapy, which are drugs that kill rapidly growing cells, like cancer cells, is generally considered second-line treatment for melanoma. Radiation therapy is an uncommon treatment for melanoma and only used in select cases.


While you cannot control all of your risk factors for developing melanoma (e.g., having fair skin or your family history), you can protect yourself from being exposed to ultraviolet (UV) rays from the sun.

Strategies to reduce your overall UV exposure include:

  • Avoiding the sun during midday (especially from 10 a.m. to 2 p.m.)
  • Using protective clothing to cover your skin
  • Applying sunscreen
  • Seeking shade to reduce sun exposure
  • Wearing sunglasses and a hat, or using an umbrella when outside in the sun
  • Avoiding tanning beds and sunlamps

Performing Skin Self-Exams

In addition to minimizing UV exposure, performing regular skin self-exams is important for detecting a new or abnormal growth before it has the chance to turn into melanoma or another type of skin cancer.

When doing a skin self-examination, you need to look at all areas of your body, including your elbows, underarms, buttocks, back, back of your neck, scalp, palms, soles of your feet, spaces between your toes, and underneath your nails. It helps to have a mirror to view difficult-to-see areas.

Look for any changes to color, shape, and size to any freckle, mole, blemish or any reddened, itchy, or bleeding areas. If you find anything concerning, make an appointment to see your dermatologist.

There is no set guideline on how often to perform self-skin exams. Therefore, it's best to talk with your healthcare provider about the right time frame for you.

A Word From Verywell

A major takeaway message here is that if you find a new or changing mole, patch, or spot on your skin, don't ignore it. Get it looked at as soon as possible by a dermatologist. Skin cancers can be treated if found early, but they can be life-threatening if left to advance.

Lastly, as with all type of cancers, prevention is key. This includes reducing your exposure to direct sunlight and other forms of UV radiation, and covering up with sunscreen and protective clothing as much as possible.

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