Melanoma spots typically look different from normal moles in specific, recognizable ways: uneven shape, irregular borders, multiple colors, a size larger than 6 millimeters (about a quarter inch), and visible changes over weeks or months. But not all melanomas follow this pattern. Some are pink instead of dark, some hide under fingernails, and some are smaller than a pencil eraser. Knowing the full range of what melanoma can look like gives you the best chance of catching it early.
The ABCDE Rule for Spotting Melanoma
The most widely used framework for identifying suspicious spots is the ABCDE rule, developed to describe features of early melanoma. Each letter flags a visual warning sign:
- Asymmetry. One half of the spot doesn’t match the other. A normal mole is roughly symmetrical. If you drew a line through the center of a melanoma, the two sides would look noticeably different in shape or thickness.
- Border irregularity. The edges are ragged, notched, or blurred rather than smooth and well-defined. Pigment may visibly spread or fade into the surrounding skin, making the boundary hard to trace.
- Color variation. Instead of a single uniform shade, you see a mix of colors within the same spot. Shades of brown, tan, and black are common, but areas of white, gray, red, pink, or blue can also appear.
- Diameter. Most melanomas are larger than 6 millimeters wide, roughly the size of a pencil eraser. That said, melanomas can be smaller than this, so size alone isn’t a reliable way to rule one out.
- Evolving. The spot has changed in size, shape, color, or texture over recent weeks or months. Any mole that looks different from how it looked before deserves attention, even if it doesn’t meet the other criteria.
No single feature on its own confirms melanoma. A spot with two or three of these features is more concerning than one with a single feature, but any evolving lesion is worth getting checked.
How Melanoma Differs From a Normal Mole
Normal moles are usually round or oval, evenly colored (one shade of brown), and have smooth, distinct edges. They tend to stay the same over time. Atypical moles, sometimes called dysplastic nevi, can blur the line. These moles may be irregularly shaped, larger than a pencil eraser, and contain a mix of colors including pink, red, tan, brown, and black. They can also have blurry or ragged edges and a flat surface with a slightly pebbly or raised center.
Atypical moles share visual features with melanoma, which is exactly why they’re worth monitoring. The key difference is behavior over time. An atypical mole that stays stable for years is less concerning than one that changes in size, color, or texture. If you have many moles, look for the “ugly duckling,” the one mole that stands out from the rest. It might be darker, larger, or shaped differently from your other spots. That outlier is the one most worth showing to a dermatologist.
Melanoma That Doesn’t Look Dark
About 5 percent of melanomas are amelanotic, meaning they lack the dark pigment most people associate with skin cancer. Instead of brown or black, these spots appear pink or red. They can look like a pimple, a scar, or an irritated patch of skin, which is why they’re often overlooked or confused with harmless conditions. Because of this, amelanotic melanoma tends to be diagnosed at a later stage compared to pigmented melanomas.
If you have a pink or reddish bump that doesn’t heal, keeps growing, or feels firm to the touch, it’s worth having it examined. The absence of dark color doesn’t rule out melanoma.
Nodular Melanoma: Fast-Growing and Raised
Nodular melanoma accounts for roughly 9 to 15 percent of all melanoma cases and behaves more aggressively than other types. Instead of spreading outward across the skin’s surface first, it grows downward quickly, penetrating deeper layers of skin in less time. These spots are typically raised, dome-shaped, and firm. They can be brown, black, or blue-black, but up to half of nodular melanomas lack typical dark pigment and may appear pink or skin-colored instead.
The hallmarks to watch for are a spot that is elevated, feels firm when touched, and is actively growing over a period of weeks. Nodular melanomas are also more likely to bleed, crust over, or develop a scaly surface. Because they grow vertically rather than spreading wide, they may not trigger the usual ABCDE warning signs early on, particularly the irregular border and large diameter that people are taught to look for.
Melanoma Under Fingernails and on Palms or Soles
Melanoma can develop in places most people never think to check. Acral lentiginous melanoma appears on the palms of the hands, soles of the feet, and under fingernails or toenails. This subtype accounts for a higher proportion of melanoma diagnoses in Black, Hispanic, and Asian populations, partly because other forms of melanoma (which are linked to UV exposure on lighter skin) are less common in these groups.
On the palms or soles, acral melanoma typically starts as a flat, tan-to-black patch with irregular, asymmetric borders. It grows slowly at first, then can develop into a raised nodule as it becomes more invasive. Under a nail, melanoma most commonly appears as a dark brown or black vertical streak running from the base of the nail to the tip. The streak may be irregular in color, with varying shades of blackish brown. Over time, the streak can widen, multiply, or cause the nail to split, crack, or lift away from the nail bed.
One important sign of nail melanoma is the Hutchinson sign, where the dark pigment extends beyond the nail itself and discolors the surrounding skin at the base or sides of the nail. In about 27 percent of acral melanoma cases, the lesion appears without any dark pigment at all, showing up instead as an unexplained nodule, swelling, or nail damage. This makes it particularly easy to mistake for a fungal infection, bruise, or ingrown nail, which is why subungual melanoma is frequently diagnosed late.
What Changes to Watch Over Time
The “E” in the ABCDE rule (evolving) may be the single most useful warning sign. A spot that changes is more suspicious than a spot that simply looks unusual but has stayed the same for years. Changes worth noting include a mole that gets larger, develops new colors, becomes raised when it was previously flat, starts itching or bleeding, or develops a crusty or scaly surface.
Taking photos of your moles every few months gives you a reliable reference point. Memory alone isn’t enough to track subtle shifts in size or color. Pay particular attention to any new spot that appears after age 30, since most new moles develop earlier in life. A brand-new dark spot in your 40s, 50s, or beyond is more likely to be something that warrants a closer look.
When checking your skin, don’t skip areas that get little sun exposure. Check between your toes, the soles of your feet, your scalp (use a mirror or ask someone to help), and your nail beds. Melanoma can develop anywhere on the body, including places that have never been sunburned.