Skin cancer can often look similar to a mole, but there are some key differences to look out for. A person can use the ABCDE rule to help distinguish between a mole and melanoma. However, a person should contact a doctor if they notice a new mole or any changes to current moles.

A mole, also known as a nevus, is a common skin growth made up of melanocytes, which produce pigment in the skin. Most moles are harmless and do not require treatment, but they can develop into melanoma in some instances.

Melanoma is a type of skin cancer that arises from the melanocytes, the same cells that produce pigment in moles. Melanoma can be life threatening if not detected and treated early.

Moles on a person's back -1Share on Pinterest
W2 Photography/Stocksy

The ABCDE rule is a helpful tool for identifying potential signs of melanoma, a type of skin cancer:

  • A Asymmetry: The two halves of a mole do not match.
  • B Border irregularity: The edges of the mole or spot are uneven or blurred.
  • C — Color: The mole or spot has varying shades of color or is an unusual color, such as blue or red.
  • D Diameter: The mole or spot is larger than 6 millimeters or about the size of a pencil eraser.
  • E Evolution: The mole or spot changes in size, shape, color, or texture or looks different from other moles or spots on the skin.

Not all melanomas follow these guidelines, and some may not have all of these features.

If someone notices any changes in a mole or spot on their skin or has any concerns, it is important to get it checked by a doctor or a dermatologist. Early detection and treatment of melanoma are crucial for a good outcome.

Symmetry refers to the uniformity of shape and appearance on either side of an object or structure.

Moles are typically symmetrical in shape. This means that if someone were to draw a line through the middle of the mole, both sides would appear the same, or very similar.

Melanomas may have an asymmetrical shape, so the two halves of the mole or spot do not match each other.

Moles typically have a well-defined and even border that separates the mole from the surrounding skin. The border of a mole is usually smooth and regular.

Moles may be slightly raised or flat, but the mole’s border is usually distinct from the surrounding skin.

Melanomas may have an irregular or poorly defined border that blends into the surrounding skin. The border of a melanoma may be uneven, notched, or blurred.

The color of the growth can be an indicator of melanoma.

Moles are usually uniform in color and can be brown, black, or skin-colored. They may have a smooth surface and a clearly defined border.

Melanomas may have an unusual coloring or variation in color, which can be a warning sign of the disease.

They may have multiple colors or shades within the same mole or spot, such as black, brown, red, white, or blue. The coloring of melanoma may also appear to be uneven or change over time.

It is important to note that some harmless moles, such as Spitz nevus, can have more than one color.

The American Cancer Society notes that moles are typically small, usually no larger than 6 mm, or about the size of a pencil eraser. Most moles are not a cause for concern unless they change in appearance or size over time.

Melanomas may be larger than 6 mm in diameter. The size of a melanoma can vary, but any new mole or spot larger than 6 mm in diameter, or any existing mole that has grown larger, calls for an investigation.

Moles typically remain the same in appearance over time and do not change in size, shape, color, or texture.

However, some moles develop in childhood or adolescence and fade or disappear as a person ages. Some moles can change in color, shape, size, and texture for various reasons, including hormonal changes, sun exposure, and aging.

Moles may become darker, lighter, or even disappear over time, while others may raise or become more prominent but still be benign.

Melanomas may evolve or change in appearance over time. This change can include a mole or spot that grows larger, changes in shape or color, becomes raised or bumpy, or develops new symptoms, such as bleeding, itching, or crusting.

A doctor or dermatologist should evaluate any changes in a mole or spot on the skin, as they can be a warning sign of melanoma.

People may mistake a dysplastic nevus as a sign of skin cancer. A dysplastic nevus is a type of benign mole that appears different from common moles.

A person has a greater chance of developing melanoma if they have many dysplastic nevi. However, most do not turn into cancer.

A dysplastic nevus:

  • is large
  • can have a mixture of colors, including pink, tan, or brown
  • does not have an oval or round shape
  • does not have a defined edge

Performing regular self-screenings for skin cancer is an important step for individuals in detecting any changes in moles or spots on their skin.

People can use the ABCDE rule to assess each mole or spot for potential signs of melanoma.

The American Academy of Dermatology Association (AAD) recommends:

  • standing in front of a full-length mirror and examining the skin for any new or changing moles, spots, or lesions, checking the entire body, including the scalp, back, and soles of the feet
  • using a handheld mirror to examine areas that are hard to see, such as the backs of the thighs or the back
  • paying attention to the size, shape, color, and texture of each mole or spot and noting any changes since the last self-screening

Individuals who notice any unusual or changing moles or spots on their skin, or have any concerns about a spot on their skin, should make an appointment with a doctor or dermatologist for a professional evaluation.

Ugly duckling test

One helpful technique for self-screening is the ugly duckling test. This test involves identifying any moles or spots that look different from other moles or spots on the body.

If someone notices a mole or spot that looks significantly different from their other moles or spots, this could be a warning sign of melanoma.

Learn more

Learn more about the appearance of moles and skin cancer:

If a person develops a new mole or notices changes to their existing moles, they should contact a doctor. More changes to watch out for include a mole or spot that bleeds or becomes itchy and painful.

If an individual has a family history of melanoma or has a high risk of developing the disease, such as having fair skin or a history of sunburns, a doctor or dermatologist should check their skin regularly.

Learn more about screening for skin cancer.

Skin cancer is a condition that a person can mistake for a mole because of its similar appearance. However, it is important for a person to be aware that there are some key differences between the two.

People can use the ABCDE rule to help distinguish between a common mole and skin cancer.