An Overview of Melanoma

Learn the Warning Signs of the Most Dangerous Type of Skin Cancer

Melanoma is a skin cancer that arises from a skin cell called a melanocyte, which makes a brown pigment (called melanin) that gives your skin its tan or brown color. While anyone can get melanoma, excess sun exposure, having fair skin, and having a family history of melanoma all increase a person's risk.

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. Diagnosis of melanoma requires a visual examination and a skin biopsy by a doctor who specializes in skin conditions (called a dermatologist).

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. Once diagnosed, melanoma treatment usually entails surgery, and sometimes taking one or more medications, like immunotherapy or targeted therapy.

 Verywell / Alexandra Gordon


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, considering the 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 or excessive sun exposure
  • 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 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.

Subtypes and Symptoms

There are four main subtypes of melanoma, each with their own skin characteristics.

Superficial Spreading

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

Nodular Melanoma

After superficial spreading melanoma, nodular melanoma is the next most common type of melanoma in fair-skinned individuals. Instead of growing outwards, though, 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 five percent of all melanomas; however, it is the most common type among dark-skinned 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.

Mimicking Conditions

Sometimes, acral lentiginous can mimic benign (non-cancerous conditions) like warts, ingrown toenails, calluses, or athlete's foot.

Other Symptoms

Besides the above-mentioned skin changes based on melanoma subtype, other potential 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 the mole like a lump or bump
  • Spread of pigment from the border of the mole into the surrounding skin
  • Redness or swelling surrounding the mole

Late Symptoms

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


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

Skin Examination

During the skin exam, the doctor 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, called the ABCDE rule of melanoma, is often utilized by a dermatologist during the skin exam.

The ABCDE rule can also be utilized by patients as a warning sign to contact a dermatologist as soon as possible.

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

  • Asymmetry: Normal moles or freckles are completely symmetrical. If you were to draw a line through a normal spot, you would have two symmetrical halves. In the case of skin cancer, spots will not look the same on both sides.
  • Border: Unlike regular (non-cancerous) moles, melanomas often have an irregular border or edge. In other words, a mole or spot with blurry and/or jagged edges would be considered concerning.
  • Color: Melanomas tend to be "more colorful" than regular moles, with colors varying from flesh-colored to the typical dark brown or black of a mole, to red. Different colors or shades (lightening or darkening) occurring in the same mole are also of concern, and some melanomas have a classic "red white and blue" appearance.
  • Diameter: Melanomas tend to be larger than normal moles (but certainly not always.) Any mole that has a diameter that is the same or larger than the diameter of a pencil eraser should be evaluated.
  • Evolution: This refers to any component of the mole, for example, it could be changing in size, in color, in shape, or in the degree of elevation. The mole may also change in texture, for example, becoming scaly.

"Ugly Duckling" Sign

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.

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 doctor 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.

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.

Take Home Message

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


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 the overall health of the affected individual.


For those with early-stage melanoma, surgery to remove the lesion (along with a small margin of healthy tissue) may be all that is needed. 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.

Avoiding UV Exposure

Strategies to reduce your overall UV exposure include:

  • Avoiding the sun during midday (especially from 10 am to 2 pm)
  • 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.

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

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, and then make an appointment to see your dermatologist.

A quick review of the ABCDE warning signs of melanoma to watch out for include:

  • A - Asymmetry
  • B - Border
  • C - Color
  • D - Diameter
  • E - Evolution

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. Don't let a little problem suddenly become a life-threatening one.

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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