Melanoma typically appears as an unusual mole or dark spot that stands out from the rest of your skin. It can be flat or raised, and it often has uneven coloring, irregular edges, or an asymmetric shape. But melanoma doesn’t always look the way people expect. Some forms are pink or skin-colored, some hide under fingernails, and others resemble a harmless age spot for years before becoming dangerous. Knowing the full range of what melanoma can look like gives you a real advantage in catching it early.
The ABCDE Checklist
Dermatologists use five visual features to evaluate suspicious spots. These aren’t a diagnosis on their own, but they’re a reliable starting framework for deciding whether a mole deserves a closer look.
- Asymmetry: One half of the spot doesn’t match the other. A normal mole is usually roughly symmetrical.
- Border irregularity: The edges are ragged, notched, or blurred rather than smooth. Pigment may seem to bleed into the surrounding skin.
- Color variation: 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 lesion.
- Diameter: Most melanomas are larger than 6 millimeters at diagnosis, roughly the size of a pencil eraser. Lesions above that threshold are significantly more likely to be melanoma on biopsy than smaller ones. That said, melanomas can be tiny, so size alone shouldn’t reassure you.
- Evolving: The spot is changing in size, shape, or color over weeks or months. Any new or shifting mole is worth having examined.
The Four Main Types and How They Differ
Superficial Spreading Melanoma
This is the most common form. It starts as a flat or slightly raised brown spot and grows outward across the skin surface for months or even years before it begins to invade deeper tissue. It’s typically larger than 6 millimeters, with irregular, asymmetric borders and patches of black, blue, or pink mixed into the brown. Because it stays relatively flat for a long time, people sometimes dismiss it as a changing freckle or age spot.
Nodular Melanoma
Nodular melanoma looks and behaves very differently. Instead of spreading outward, it grows downward into the skin almost immediately after appearing. It usually shows up as a dome-shaped bump or raised nodule, most often dark brown to black. About 5% of nodular melanomas have no dark pigment at all, appearing pink or red, which makes them especially easy to mistake for a blood blister or a small benign growth. This type is more dangerous precisely because it skips the slow horizontal phase and becomes invasive quickly.
Lentigo Maligna
Lentigo maligna develops on sun-damaged skin, most often on the face or neck of people over 60. It starts looking like an ordinary freckle or brown sun spot, then slowly becomes larger and more irregular over years or even decades. By the time it’s diagnosed, it’s often several centimeters across. The color is variable: light tan, dark brown, pink, red, or white patches within the same lesion. Its surface stays smooth and flat. Because it appears on skin that’s already covered in sun damage spots, it blends in easily and gets overlooked.
Acral Lentiginous Melanoma
This type appears on the palms of the hands, soles of the feet, or under the nails. On the palm or sole, it looks like a dark brown or black discoloration that resembles a bruise or stain, but unlike a bruise, it doesn’t fade. It grows in size over time. Under a nail, it shows up as a dark streak or band running vertically along the nail bed. As it progresses, the nail may crack or break. This form is sometimes mistaken for a fungal infection or an injury. It’s the most common type of melanoma in people with darker skin tones, partly because other types are harder to spot on darker skin and partly because this location gets less routine screening.
Melanoma Without Dark Pigment
About 5% of all melanomas are amelanotic, meaning they produce little or no pigment. These appear as pink, red, or skin-colored spots rather than the dark brown or black lesions most people associate with melanoma. They can look like a pimple that won’t heal, a small scar, or an irritated patch of skin. Because they lack the visual cues people are taught to watch for, amelanotic melanomas tend to be diagnosed at a later, more advanced stage. If you have a pink or reddish spot that persists for several weeks, doesn’t heal, or slowly grows, it’s worth getting checked even though it doesn’t look “typical.”
The Ugly Duckling Sign
The ABCDE criteria work well when you’re evaluating a single spot, but there’s a complementary approach that’s just as effective: looking at all your moles together. Most people’s moles share a general family resemblance. They tend to be roughly the same color, size, and shape. The “ugly duckling” is the one mole that doesn’t fit the pattern. It might be darker than the rest, a different shape, or just visually out of place.
A study published in collaboration with French researchers tested this approach by having nine dermatologists examine images of over 2,000 moles from 80 patients. The doctors flagged melanomas just as accurately using the ugly duckling method as they did evaluating each mole individually against diagnostic criteria. The ugly duckling approach actually reduced unnecessary biopsies. So when you’re doing a self-check, step back and look at the big picture. The spot that looks nothing like your other moles is the one that deserves attention.
What Melanoma Doesn’t Look Like
One of the trickiest parts of spotting melanoma is distinguishing it from harmless growths. Seborrheic keratoses are an extremely common example. These are raised, waxy, slightly discolored patches that look like they’ve been stuck onto the skin surface. They can be dark brown and rough-textured, which sometimes causes alarm. But they tend to be painless, have a well-defined “pasted on” quality, and their surface often looks scaly or crumbly rather than smooth. Melanoma, by contrast, tends to have irregular borders that blend into surrounding skin, uneven pigmentation with multiple colors, and an asymmetric shape.
A normal mole is usually one consistent color, has smooth and even borders, is roughly symmetrical, and stays the same over time. It can be flat or raised, light or dark brown, but the key is stability. A mole that has looked exactly the same for years is far less concerning than one that appeared recently or started changing.
What “Evolving” Actually Means
The “E” in ABCDE is arguably the most important letter because it captures something the other four don’t: change over time. A perfectly round, evenly colored mole that suddenly starts growing or darkening is more concerning than an oddly shaped mole that’s looked the same for a decade. Evolution can mean a spot that’s gotten bigger, shifted in color, developed a new border irregularity, or started itching, bleeding, or crusting. There’s no single threshold of weeks or months that makes a change dangerous. The relevant question is whether something is different from how it used to look. Taking photos of your moles every few months gives you an objective record to compare against, which is far more reliable than memory.
Pay particular attention to any spot that is entirely new, especially after age 30, when new moles become less common. A brand-new dark spot on previously clear skin is worth examining more carefully than a mole you’ve had since childhood.