A concerning mole is one that looks different from your other moles, has changed recently, or shows specific visual warning signs like uneven color, irregular borders, or a diameter larger than 6 millimeters (about the size of a pencil eraser). The good news: when melanoma is caught while still localized to the skin, the five-year survival rate is above 99%. Knowing what to look for makes early detection far more likely.
The ABCDE Rule for Spotting Suspicious Moles
Dermatologists use a five-feature checklist to evaluate moles. Each letter flags a characteristic of early melanoma:
- Asymmetry: One half of the mole doesn’t match the other. Normal moles tend to be roughly symmetrical.
- Border: The edges are ragged, notched, or blurred rather than smooth. Pigment may spread into the surrounding skin.
- Color: The mole contains uneven shades of brown, black, or tan. Areas of white, gray, red, pink, or blue are especially suspicious.
- Diameter: The mole is wider than 6 millimeters, roughly the width of a pencil eraser. That said, melanomas can be smaller, so size alone isn’t enough to rule one out.
- Evolving: The mole has changed in size, shape, color, or texture over the past few weeks or months. Any noticeable change counts.
No single feature confirms melanoma on its own. A mole with one or two of these traits may still be benign. But the more features present, the more reason to have it evaluated by a dermatologist.
Physical Symptoms That Go Beyond Appearance
Not all warning signs are visual. A mole that bleeds without being scratched or injured, feels itchy or sore for no clear reason, becomes crusty or scaly on the surface, or appears swollen and inflamed deserves attention. These symptoms can indicate that cells within the mole are behaving abnormally, even if the mole doesn’t look dramatically different from before. Melanoma that has progressed may also appear hard or lumpy, or ooze fluid.
The Ugly Duckling Sign
Most people’s moles share a general “family resemblance.” They tend to be similar in size, shape, and color. The ugly duckling sign is a screening approach based on a simple idea: the mole that looks nothing like the others is the one most worth watching. If you have a dozen small, round, light brown moles and one that’s darker, larger, or shaped differently, that outlier is the one to show a dermatologist. This method catches melanomas that might not clearly meet every ABCDE criterion but still stand out as unusual in the context of your skin.
Atypical Moles vs. Melanoma
Some people have what are called atypical (or dysplastic) moles. These are moles that look a bit unusual, often wider than 5 millimeters, with irregular edges and a mix of tan, brown, and pink shades. They can look alarming, but they are not cancer. Only rarely does an atypical mole turn into melanoma, and most melanomas don’t start from atypical moles at all.
The distinction matters, though, because having many atypical moles raises your overall risk. Someone with more than five atypical moles has roughly ten times the melanoma risk of someone with none. If your dermatologist has told you that you have atypical moles, regular skin checks become especially important.
One practical way to tell the difference: atypical moles may have an uneven surface texture, but they don’t break down, bleed, or ooze. Melanoma can. An atypical mole that stays stable over time is generally not a problem. One that starts evolving is.
What Looks Different on Darker Skin
The ABCDE rule was developed primarily from melanomas on lighter skin, so it can miss a specific subtype called acral melanoma that disproportionately affects people with darker skin tones. This type appears on the palms, soles of the feet, and under the nails, areas that are easy to overlook during a skin check.
On the palms and soles, these lesions often show up as dark brown or black spots with relatively even pigmentation. Sometimes they’re pink or red instead, which makes them even harder to recognize. Under a nail, acral melanoma typically appears as a dark streak running the length of the nail, sometimes extending into the surrounding skin or causing the nail to split.
A separate screening tool called CUBED has been proposed for these hard-to-spot locations. It flags lesions that are colored (pigmented), ulcerated or bleeding, uncertain in diagnosis, enlarged, or deteriorating with delayed healing. If you notice a sore on your palm, sole, or nail bed that isn’t healing or a new dark streak under a fingernail or toenail, it’s worth getting checked.
Concerning Moles in Children
Pediatric melanoma is rare, but it doesn’t always follow the adult playbook. In younger children, warning signs include a pale or red bump (rather than the dark, irregular mole adults typically look for), a mole or bump that itches or bleeds, and any mole that changes noticeably or appears unusually large or oddly shaped. In adolescents, the signs look more like adult melanoma: asymmetry, color changes, growing size, and irregular borders. The takeaway is that a bump or mole on a child that seems “off” warrants evaluation, even if it doesn’t match the classic ABCDE description.
How to Check Your Skin at Home
A monthly self-exam is the simplest way to catch changes early. The best time is after a bath or shower, when your skin is bare and well-lit. Work systematically from head to toe so you don’t skip areas.
The spots people miss most often are the ones they can’t easily see: the back, buttocks, genital area, the skin beneath the breasts, the scalp, the soles of the feet, and between the toes. Use a handheld mirror combined with a wall mirror to check your back and scalp. Sit down to inspect the bottoms of your feet and between each toe. If you have a partner, ask them to check your scalp and back.
What you’re looking for isn’t perfection in identifying melanoma. You’re looking for change. A new mole that wasn’t there before, an existing mole that looks different than it did a few months ago, or one mole that simply doesn’t look like the rest. Taking photos of moles you’re monitoring can help you track subtle shifts in size or color over time. If something looks different, let a dermatologist take a closer look with a dermoscope, a magnifying instrument that reveals patterns beneath the skin’s surface invisible to the naked eye.