A cancerous mole is a sign of melanoma of the skin. A cancerous mole is typically a new mole or an existing mole that has undergone certain changes. Treatment may involve surgery to remove the mole.

Although not every new or changing mole is cancerous, it is important that people keep track of their moles.

Melanoma is not the most common form of skin cancer, but it is often the most serious. This is because it can quickly spread to other parts of the body, making treatment difficult and often resulting in a poor outlook.

However, getting an early diagnosis and receiving prompt treatment can significantly improve the outlook for people with melanoma. This is why it is important for people to stay vigilant and regularly check their skin.

A common risk factor for cancerous moles is excessive exposure to UV radiation. Therefore, it is vital for people to take precautions such as limiting sun exposure, wearing protective clothing when outside, and using a broad-spectrum sunscreen.

This article will discuss the causes of melanoma, some treatment options, and some prevention tips.

A cancerous mole, or melanoma, is the result of damage to DNA in skin cells. These changes, or mutations, to the genes can result in cells growing rapidly and out of control.

Melanoma is a type of skin cancer that occurs when pigment-producing cells known as melanocytes mutate and begin to divide uncontrollably. Melanocytes produce a pigment called melanin.

Melanin is responsible for the color of the skin. After exposure to sunlight, melanocytes increase the production of melanin to protect the skin against potentially harmful UV rays. This is why some people may tan after exposure to sunlight.

The bodies of people with darker skin naturally produce more melanin than those with lighter skin. This means that people with darker skin have somewhat more natural protection from UV rays.

However, it is still possible for individuals with darker skin to develop cancerous moles, so these groups should also take appropriate precautions. Although cancerous moles are less common in people of color, they usually have worse outcomes, as the melanoma that occurs in darker skin types tends to be more aggressive.

Moles are clusters of melanocytes. This is why the rapid division of damaged melanocytes can result in the development of cancerous moles. However, not every mole is cancerous. In fact, most are harmless.

Excessive exposure to UV light, particularly UVA and UVB, is the most common cause of cancerous moles. The main source of UV light is sunlight, but artificial sources of light, such as tanning beds, also produce UV light.

In some cases, people may also inherit gene mutations from their parents, which can increase their chance of developing cancerous moles.

It can be difficult to identify a cancerous mole in the early stages of melanoma. For this reason, people should check their skin regularly for any signs of change, such as a new mole or a change in the appearance of an existing mole.

If a person suspects that a mole may be cancerous, it is important for them to see their dermatologist for a diagnosis.

The Melanoma Research Foundation list some symptoms that people should be aware of. These include:

  • any changes to the skin, such as a new mole or a change in the color, shape, or size of an existing mole
  • a mole that does not heal or becomes painful or tender
  • a mole that becomes itchy or begins to bleed
  • a mole that has a shiny, waxy, smooth, or pale appearance
  • a firm, red lump that bleeds or appears crusty (this is particularly concerning for amelanotic melanoma, which tends to go unnoticed more often because it lacks pigment)
  • a flat, red spot that is rough, dry, or scaly
  • a black or dark spot or streak under a fingernail or toenail that has not come from previous trauma to the nail (nail melanomas tend to be more aggressive)

People can also follow the ABCDE examination rule to check potentially cancerous moles. This rule describes five simple characteristics of early melanoma. These features are:

  • Asymmetry: One half of a cancerous mole is likely to look different than the other half.
  • Border: This may be irregular, meaning that the edges are ragged, notched, or blurred instead of smooth.
  • Color: They may contain uneven shades and colors, typically black, brown, or tan. Some may include white, gray, red, pink, or blue areas.
  • Diameter: Cancerous moles can change in size, usually growing larger. If a mole becomes larger than 6 millimeters (one-quarter of an inch), it may be cancerous.
  • Evolving: A change in the appearance of a mole over weeks or months may indicate that it is cancerous.

People can also use the “ugly duckling” method. This strategy relies on the notion that any cancerous moles will stand out like an “ugly duckling” in comparison with a person’s other moles. If a person is concerned about a mole’s appearance, they should contact a dermatologist for a full diagnosis.

It is important to note that only about 20–30% of melanomas arise from a preexisting mole. The majority present as a new mole.

People may be able to detect the early symptoms of a cancerous mole by using the ABCDE rule and regularly examining any new and existing moles.

People should try to check all areas of their skin, including their back and other areas that may be difficult to see without assistance. They can use a mirror or phone or ask a partner, family member, friend, or doctor to help with these areas.

If a person has any worries or concerns about a mole, they should see a dermatologist, who can use microscopic or photographic tools to examine a mole in more detail.

Other physicians may not have received the training necessary to identify abnormal moles, potentially leading to unnecessary biopsies and even potentially delaying care.

A dermatologist is specially trained to identify abnormal moles and melanomas. However, even with their years of training, this can sometimes be difficult.

If a dermatologist suspects that a mole may be cancerous, they may perform a biopsy. This is a procedure wherein a healthcare professional takes a sample of a mole and sends it for examination in a laboratory.

The treatment for a cancerous mole is typically the same as it is for other cancers. However, unlike cancers of the internal organs, it will be easier to access the cancerous tissue and remove the mole with surgery. Therefore, surgery is often the main treatment option for most cancerous moles.

The procedure typically involves removing the mole and some of the surrounding noncancerous tissue. In some cases, when a person has received an early diagnosis, surgery may be a sufficient remedy to treat the cancerous mole. If the mole covers a large area of skin, a skin graft may be necessary after the surgery.

Usually, a surgeon will perform the excision while a person is under local anesthetic. This means that a person will be awake during the procedure, but they will not feel any pain, as the surgeon will have numbed the affected area.

The surgeon will send this sample of removed tissue to pathology to determine the extent of the involvement of the cancer.

If there is any risk that the cancer has spread into other organs, bones, or blood, a doctor may perform further exams, such as a lymph node biopsy, radiologic studies, or both.

If the cancer has spread, a doctor will request treatments depending on where in the body it has spread to. These may include:

There is no sure way to prevent cancerous moles. Some risk factors — such as age, fair skin, and family history — can make certain people more likely to develop cancerous moles.

That said, people can take some appropriate precautions to reduce their risk of developing skin cancer.

Most importantly, people should avoid excessive exposure to UV radiation. They can achieve this by seeking shade, using sunscreen, and wearing clothes that protect the body from the sun when outside. Doctors also recommend avoiding tanning booths, lamps, and beds.

People should also regularly check their skin to identify any new or changing moles, especially if they have a family history of melanoma.

Melanoma of the skin is an aggressive type of skin cancer that commonly presents as a cancerous mole.

It is important for people to regularly monitor their moles and seek medical attention for any that are new, changing, irregular, or growing.

People should also take appropriate preventive measures, such as limiting their UV exposure and applying sunscreen.