Most melanomas announce themselves through visible changes you can spot on your own skin. The key is knowing what to look for: asymmetry, irregular borders, multiple colors, a size larger than 6 millimeters (about the width of a pencil eraser), and any change over time. When melanoma is caught early and still confined to the skin, the five-year survival rate is above 99%. That number drops significantly once it spreads, which is why recognizing the warning signs matters so much.
The ABCDE Rule
Dermatologists use a five-letter framework to describe the features of early melanoma. Each letter flags a specific trait that separates suspicious spots from ordinary moles.
- Asymmetry. If you drew a line through the middle of the spot, the two halves wouldn’t match. Normal moles are roughly symmetrical.
- Border. The edges are ragged, notched, or blurred rather than smooth. Pigment may seem to bleed into the surrounding skin.
- Color. Instead of one uniform shade, you see a mix of brown, tan, black, or even patches of white, gray, red, pink, or blue within the same spot.
- Diameter. Most melanomas are larger than 6 millimeters across, roughly the size of a pencil eraser. But melanomas can be smaller, especially early on.
- Evolving. The mole has changed in size, shape, or color over the past few weeks or months. This is often the single most important sign.
A spot doesn’t need to check every box to be concerning. Even one of these features, particularly a mole that is clearly evolving, is worth getting examined.
The “Ugly Duckling” Approach
Your moles generally share a family resemblance. They tend to be similar in size, shape, and color. The ugly duckling method takes advantage of this: instead of evaluating each mole in isolation, you scan your skin and look for the one that doesn’t match the rest. It’s the spot that stands out from its neighbors, the mole that looks like it doesn’t belong. Dermatologists use this comparison technique alongside the ABCDE criteria, and research from Harvard’s Wyss Institute found that a quantified version of the ugly duckling metric matched the consensus of three dermatologists 88% of the time. In practice, this means you don’t need to memorize a checklist for every mole on your body. You just need to notice the outlier.
Melanoma That Doesn’t Look Like a Mole
Not all melanomas follow the textbook pattern. Some types are easier to miss because they don’t look like the dark, irregularly shaped mole most people picture.
Nodular Melanoma
This type often grows as a raised, dome-shaped bump rather than a flat, spreading spot. It may be uniformly dark or even skin-colored. Because it grows downward into the skin rather than outward, it can be more dangerous by the time it’s noticed. The warning signs go by a separate set of letters: EFG. The spot is elevated above the skin surface, firm to the touch (more solid than soft), and growing over weeks or months.
Amelanotic Melanoma
About 5% of melanomas lack the dark pigment people associate with skin cancer. These appear as pink or red spots on the skin and are frequently mistaken for a pimple, rash, or scar that won’t heal. Because they’re so easy to overlook, amelanotic melanomas tend to be diagnosed at a later stage than their darker counterparts. If you have a pinkish bump or sore that persists for more than a few weeks without a clear explanation, that’s worth attention.
Melanoma on Palms, Soles, and Under Nails
Acral lentiginous melanoma shows up in places people rarely think to check: the palms of the hands, the soles of the feet, and under the nails. On the palms or soles, it typically starts as a brown or black discoloration that resembles a bruise or stain but grows over time rather than fading.
Under the nails, melanoma usually appears as a dark vertical streak running from the base of the nail to the tip. The streak may be irregular in color and can widen over time. One important clue is the Hutchinson sign, where the dark pigment extends beyond the nail itself and discolors the surrounding skin. As the melanoma progresses, the nail may split, crack, lift from the nail bed, or develop a nodule underneath. These changes are sometimes mistaken for a fungal infection or an old injury, so any persistent dark streak under a nail that you can’t trace to a specific trauma deserves a closer look.
Symptoms Beyond Appearance
Visual changes are the primary warning, but melanoma can also produce physical sensations. A mole that itches persistently, bleeds without being scratched or bumped, or feels tender is more suspicious than one that’s painless. Some melanomas develop a crust on the surface or become a sore that refuses to heal. These symptoms don’t always mean cancer, but they do signal that something in the skin is actively changing, and that change needs an explanation.
The ABCDE criteria capture most melanomas, but not all of them. Any new bump, rash, or sore that persists without a clear cause is worth having examined, even if it doesn’t fit neatly into the standard framework.
How to Do a Self-Exam
A thorough skin check takes about 10 to 15 minutes. You’ll need a full-length mirror, a hand mirror, and good lighting. Start with your face, ears, and neck. Move to your chest, abdomen, and arms, checking both the tops and undersides. Use the hand mirror to examine your back, buttocks, and the backs of your legs. Check your palms, the spaces between your fingers, your fingernails, the soles of your feet, your toenails, and the skin between your toes.
The point isn’t to diagnose yourself. It’s to build a mental map of what your skin normally looks like so you’ll notice when something changes. Taking photos of moles you want to track can make it much easier to spot subtle shifts in size, shape, or color over the following months.
What Happens If a Spot Looks Suspicious
A doctor who suspects melanoma will typically want to biopsy the spot, which means removing all or part of it so a pathologist can examine the cells under a microscope. The preferred approach is an excisional biopsy, where the entire lesion is removed along with a small margin of normal skin around it. For smaller spots (under 4 millimeters), a punch biopsy, which takes a small cylindrical core of tissue, is sometimes used instead.
The biopsy matters because visual inspection alone can’t confirm melanoma. It also determines how deep the melanoma has grown into the skin, which is the most important factor in staging and treatment planning. Partial biopsies can sometimes underestimate depth, which is why full removal of the suspicious spot is preferred when it’s practical.
Why Early Detection Changes the Outcome
Melanoma survival depends heavily on how far it has progressed at diagnosis. Based on data from patients diagnosed between 2015 and 2021, the five-year survival rate for localized melanoma (still confined to the original site) is above 99%. Once it spreads to nearby lymph nodes, that drops to 76%. If it reaches distant organs, the rate falls to 35%. These numbers make a strong case that the few minutes it takes to examine your skin regularly can be genuinely lifesaving. The difference between a localized melanoma and one that has spread is often just a matter of months.