What Are the ABCDEs of Melanoma?

Updated on November 18, 2024

Medically reviewed by Gagandeep Brar, MD

The ABCDEs of melanoma stand for Asymmetry, Border irregularity, Color variation, Diameter larger than a pencil eraser (1/4 inch), and Evolving in size, shape, or color. Early-stage melanoma may look like a mole that changes in appearance, with uneven borders or multiple colors.

You can live with melanoma for months or even years without realizing it, as early stages often go unnoticed. However, melanoma can become life-threatening if it spreads to other parts of the body. Regular skin checks and early detection are key to improving survival rates.

1:50

The ABCDE Rule of Melanoma

What Are the ABCDEs of Melanoma?

The ABCDEs of melanoma are a common way to remember the signs of early melanoma. Look out for these signs:

Asymmetry: One half of the mole looks different from the other half.
Border: The edges of the mole are uneven, irregular, or poorly defined.
Color: The color of the mole is not uniform and may include shades of brown, black, tan, red, white, or blue.
Diameter: The mole is larger than 6 mm (1/4 inch) or about the size of a pencil eraser.
Evolving: The mole or spot is changing in size, shape, color, or thickness over time.

You don’t have to have all the ABCDEs for a mole to be melanoma. Even if a mole only exhibits one or a few of these characteristics, it could still be a sign of melanoma.

Can Melanoma Occur Without a Mole?

Not all melanomas begin as moles. In fact, about 20% to 30% of melanomas begin in moles while the rest begin in seemingly normal skin. Some types of melanoma may be confused for acne, age spots, or another benign (non-cancerous) lesion.

A = Asymmetry

Unlike healthy moles, melanomas are not symmetrical. One half does not match the other half in:

Size
Shape
Color
Thickness

In this picture, the left side is much thicker and darker than the right.

B = Border

While a normal mole has a smooth, consistent border, the border of a melanoma can be:

Ragged
Scalloped
Blurred
Poorly defined

The pictured melanoma has a scalloped and notched border.

C = Color

The color of melanoma isn't consistent. It can have shades of:

Tan
Brown
Black
Red
White
Blue

In this picture, the right side is dark black and the left side is tannish-red.

D = Diameter

Melanomas grow. Normal moles don't. Melanomas tend to be larger, with a diameter of more than 6 mm. For perspective, 6 mm is just under 1/4 inch or about the size of a pencil eraser.

If your mole can't be fully covered by a new pencil eraser, it's large enough to be concerned about. However, keep in mind that smaller moles or spots can be melanoma, too.

E = Evolving

Amelanotic nodular melanoma — https://dermnetnz.org/topics/amelanotic-melanoma-images/?stage=Live

The "E" in the ABCDE guide stands for "evolving." That's because melanomas change in size, shape, color, and thickness over time. Different types of melanomas grow at different speeds, so it's important to monitor your skin carefully and frequently for subtle changes.

Ugly Duckling

Most normal moles on your body resemble one another. So along with checking for irregularities in spots on your skin, you should also check for any spots that look different than neighboring moles.

These "ugly duckling" spots can be larger, smaller, lighter, or darker than surrounding moles. It might also be a spot all by itself (isolated) with no moles around it.

Other Warning Signs

Not all melanomas are detectable by ABCDE. Other warning signs include:

Sores that don't heal
Pigment "bleeding" from a border
Redness or swelling beyond the border
Itchiness or pain
Changes in the surface (scales, oozing, bleeding)

How Quickly Does Melanoma Spread?

Melanoma can spread relatively quickly compared to other skin cancers. The cancer is known to invade nearby tissues and metastasize (spread) to other parts of the body within weeks to months if not detected early.

Some types of melanoma, such as nodular melanoma, can grow from nothing to pencil eraser-size in a matter of weeks. Other types of melanoma, such as lentigo maligna, can grow for five to 20 years without being recognized.

The rate of spread varies depending on factors like the type and thickness of the melanoma, and the overall health of the affected individual. Early detection and treatment are crucial for improving outcomes and preventing further spread.

What Organs Does Melanoma Spread to First?

Melanoma usually spread into nearby lymph nodes first before entering the blood and spreading to other organs and tissues. After lymph nodes, common melanoma metastasis sites include lungs, liver, bones, and brain.

When Is Melanoma Too Late?

Melanoma is difficult to cure when it reaches stage IV. By this stage, the melanoma will have spread to other parts of the body, including distant lymph nodes and organs.

Approximately 50% of people with stage IV melanoma develop metastasis to the brain. The prognosis for brain metastasis is quite poor, with a median overall survival of about three months.

Overall, about 15% to 28% of people diagnosed with stage IV melanoma survive five years after their diagnosis.

How to Check Yourself for Skin Cancer

The American Cancer Society recommends doing a skin self-exam once a month, especially if you are at a higher risk of skin cancer. This includes:

People with reduced immunity
People who have had skin cancer before
People who have lots of moles or other skin spots
People with a strong family history of skin cancer

Before you start the self-exam, make sure you have the following:

Well-lit room
Full-length mirror
Hand-held mirror to check skin areas that are hard to see
Spouse, partner, or close friend or family member to help you check hard-to-see areas like your back and scalp

Then, follow these steps to do the self-exam:

Use the full-length mirror: Check your face, ears, neck, chest, and belly. If you have breasts, lift them and check underneath. If you have body hair, look through it as best you can. Check your underarm areas, the sides of your arms, both sides of your hands, between your fingers, and under your fingernails.
Sit on a chair: Sit and check the front and inner sides of your thighs, shins, tops of your feet, between your toes, and under your toenails.
Use the hand-held mirror: Sit and check the bottoms of your feet, your calves, around your genital area, and the backs of your thighs. Stand and check your buttocks, lower and upper back, and the back of your neck and ears. You can also do this by positioning the hand mirror so that it reflects your back into the full-length mirror.
Check your scalp: Use your mirrors to look through the hair on your scalp. It may help to make parts in your hair with a comb or blow dryer. You may need a partner to check the back of your head.

Trust your instincts. Don't hesitate to see a healthcare provider if something seems off.

When to See a Healthcare Provider

Any skin abnormality—whether mole, pimple, wart, or something else—should be evaluated by a healthcare provider or dermatologist if it:

Has any ABCDE characteristics
Grows or takes on an irregular shape
Itches
Crusts or bleeds
Doesn't heal

The appearance of a new, unusual spot or mole should also be checked out. Such changes can be signs of melanoma and other forms of skin cancer, including basal cell and squamous cell carcinomas.

Summary

Normal moles are symmetrical, small, and usually flat. They have a smooth border and consistent coloration. Melanomas are often asymmetrical, larger than 6mm, and elevated. They have irregular borders and inconsistent coloring. Melanomas change over time. Normal moles don't.

You should keep an eye on your moles. But don't trust your health to a self-exam. If anything about a mole seems off or changes, get it checked. An early melanoma diagnosis means early treatment which gives you a better outlook.