Melanoma typically appears as an unusual mole or spot that looks different from the rest of your skin. It can be brown, black, tan, red, pink, or even skin-colored, and it often has irregular borders, uneven coloring, or an asymmetric shape. Most melanomas are larger than 6 millimeters (roughly the size of a pencil eraser), though they can be smaller. What makes melanoma tricky is that it doesn’t always look the same. Its appearance depends on the type, where it is on your body, and your skin tone.
The ABCDE Rule for Spotting Melanoma
The most widely used framework for identifying melanoma is the ABCDE rule, developed by the National Cancer Institute. Each letter corresponds to a visual feature:
- Asymmetry: One half of the mole doesn’t match the other. Normal moles are roughly symmetrical.
- Border: The edges are ragged, notched, or blurred rather than smooth and well-defined. Pigment may spread into the surrounding skin.
- Color: Multiple colors appear within the same spot. You might see shades of brown, black, and tan alongside patches of white, gray, red, pink, or blue.
- Diameter: The spot is larger than 6 millimeters, though melanomas can start smaller.
- Evolving: The mole has changed in size, shape, or color over the past weeks or months. This is often the most important warning sign.
Not every melanoma will check all five boxes. Some early melanomas may only show one or two of these features. The “evolving” criterion is especially worth paying attention to, because any mole that is actively changing deserves a closer look, even if it otherwise appears unremarkable.
The Ugly Duckling Sign
Beyond the ABCDE criteria, there’s a simpler visual test: the ugly duckling sign. Most of your moles tend to look similar to one another in color, size, and shape. If one mole stands out from the rest, looking noticeably different from its neighbors, that outlier deserves attention. It doesn’t need to meet any specific criteria. If it just looks “off” compared to everything around it, that’s reason enough to have it evaluated.
Superficial Spreading Melanoma
The most common type of melanoma is superficial spreading melanoma. It grows outward across the skin’s surface before it begins to grow deeper. Visually, it tends to have uneven borders and color variations within the same spot, mixing shades of brown, black, tan, and sometimes blue or pink. It can appear on any part of the body. In women, it’s frequently found on the legs. In men, it’s more common on the trunk. These melanomas often start as a flat or slightly raised patch and may evolve from an existing mole or appear as a new spot entirely.
Nodular Melanoma: A Faster-Growing Type
Nodular melanoma looks quite different from the flat, spreading type. It typically appears as a raised, dome-shaped bump that is firm to the touch. It’s often uniformly dark brown, black, or blue-black, though it can also be red or skin-colored. What sets nodular melanoma apart is speed. It tends to grow rapidly, with noticeable changes over days to weeks rather than months.
Because nodular melanoma grows vertically into the skin rather than spreading across the surface, it may not trigger the classic ABCDE warning signs. A separate set of criteria, called the EFG rule, was designed to catch it: Elevated, Firm, and Growing. If you notice a new bump on your skin that feels firm, is raised above the surface, and is growing quickly, that combination is concerning even if the bump looks symmetric with smooth borders.
Melanoma on Palms, Soles, and Nails
Melanoma can develop in places you might not think to check. Acral lentiginous melanoma appears on the palms of the hands, soles of the feet, and under fingernails or toenails. On the palms and soles, it looks like a dark or irregularly colored patch, sometimes with uneven borders that blend into the surrounding skin.
Under the nails, melanoma typically shows up as a dark vertical streak running from the base of the nail to the tip, usually brown or black. It’s been described as looking like someone drew a line on your nail with a marker. It most commonly affects the big toe, thumb, or index finger. Over time, the streak may widen, darken, or cause the nail to crack and lift. A single dark band under one nail that wasn’t caused by injury is worth having examined.
Melanoma That Isn’t Dark
About 5 percent of melanomas lack the dark pigment most people associate with skin cancer. These are called amelanotic melanomas, and they appear as pink, red, or skin-colored spots. They can look like a pimple that won’t heal, a small scar, or even a bug bite. Because they don’t match the typical image of melanoma, they’re frequently mistaken for benign skin conditions and diagnosed at a later stage. If you have a pink or red spot on your skin that persists for weeks, doesn’t heal, or slowly grows, it’s worth getting checked, especially since these lesions can easily fly under the radar.
How Melanoma Looks on Darker Skin
Melanoma affects people of all skin tones, but its appearance and location shift in people with darker skin. The most common form of melanoma in people with dark skin is acral lentiginous melanoma, the type that appears on palms, soles, fingers, toes, and nail beds. On dark skin, melanoma can look like a dark or black bump that appears waxy or shiny, or a dark patch on the palm or sole of the foot. Dark bands under the nails are also a key warning sign.
Because melanoma awareness campaigns have historically focused on sun-exposed areas and lighter skin, melanoma in people with darker skin is more likely to be diagnosed late. Checking the hands, feet, and nails regularly matters regardless of your skin tone.
Spots That Fade or Change Color
Melanoma doesn’t always get darker over time. In some cases, the body’s immune system partially attacks the tumor, causing parts of it to fade. This can create patches of white, gray, blue, or pink within a mole or where a mole used to be. The fading may look like a scar forming in the middle of a spot. This process is called regression, and while it might seem like the spot is going away on its own, a partially regressed melanoma can still be dangerous. A mole that develops pale or scar-like areas within it, especially if those areas weren’t there before, should be evaluated.
What a Professional Sees Up Close
When a dermatologist examines a suspicious spot with a dermatoscope (a magnifying tool with polarized light), they look for patterns invisible to the naked eye. One of the most significant is something called a blue-white veil: an area of hazy blue pigment with a whitish film over it, almost like frosted glass. This pattern is highly specific to invasive melanoma and rarely appears in benign moles. They also look for irregular pigment networks, dots, and streaks at the edges of a lesion. These details explain why a mole that looks “probably fine” to you might raise concern for a trained examiner, and why skin checks with a professional add a layer of detection that self-exams alone can’t match.