Melanoma typically appears as an unusual mole or spot with uneven color, irregular borders, and asymmetric shape. It can range from dark brown or black to pink, red, or even skin-colored, which is part of what makes it tricky to spot. Most melanomas are wider than 6 millimeters (about the size of a pencil eraser), though they can be smaller. Knowing the specific visual patterns helps you catch it early, when the cure rate is highest.
The ABCDE Rule
The most widely used framework for spotting melanoma is the ABCDE rule, developed by the National Cancer Institute. Each letter flags a visual feature worth examining:
- Asymmetry: One half of the spot doesn’t match the other. A normal mole is roughly symmetrical. If you drew a line down the middle of a melanoma, the two sides would look different in shape or color.
- Border: The edges are ragged, notched, or blurred rather than smooth and well-defined. Pigment may seem to bleed or spread into the surrounding skin.
- Color: Instead of one uniform shade, you see a mix. Shades of brown, tan, and black are common, but patches of white, gray, red, pink, or blue can also appear within the same spot.
- Diameter: Most melanomas are larger than 6 millimeters wide, roughly a quarter inch. That said, melanomas can be tiny, so size alone isn’t a reliable way to rule one out.
- Evolving: The spot has changed in size, shape, or color over the past few weeks or months. Any mole that looks different from how it looked before deserves attention.
Not every melanoma checks all five boxes. Some check only one or two. The “evolving” criterion is especially important because change over time is one of the strongest warning signs, even in a spot that otherwise looks unremarkable.
How Different Types of Melanoma Look
Superficial Spreading Melanoma
This is the most common type, accounting for about 70% of all melanomas. It starts as a flat or slightly raised brown patch with irregular, asymmetric borders. Over months to years, it grows outward across the skin’s surface before it starts pushing deeper. You might see black, blue, or pink discoloration mixed into the brown. Because it spreads horizontally for a long time before becoming invasive, this type offers a wider window for early detection.
Nodular Melanoma
Nodular melanoma looks different from the flat, spreading type. Its main feature is a bump or dome-shaped node that rises above the skin and feels firm to the touch. It tends to be uniformly dark, sometimes black or blue-black, though it can also be pink or red. This type grows faster than other forms, which makes it more aggressive. It often skips the ABCDE pattern entirely because it doesn’t spread outward first. If a new firm bump appears on your skin and continues to grow over a few weeks, that’s worth having examined quickly.
Lentigo Maligna
This form typically shows up on the face, ears, or neck of older adults with years of sun damage. It appears as a large, flat, blotchy patch with uneven brown or tan coloring. The borders are often hard to make out because they blend gradually into the surrounding sun-damaged skin. It’s frequently mistaken for a harmless age spot or sun spot, which can delay diagnosis. The key difference is that lentigo maligna continues to change and grow, while a benign sun spot stays stable.
Melanoma on Palms, Soles, and Under Nails
Acral lentiginous melanoma develops in places most people don’t think to check: the soles of the feet, palms of the hands, and under fingernails or toenails. It appears as a black or brown discoloration that may look like a bruise or stain at first, but it keeps growing instead of fading. This type occurs equally across all races and skin tones, and it accounts for the majority of melanoma cases in people of color.
When melanoma develops under a nail, it’s called subungual melanoma. It usually looks like a dark vertical streak running the length of the nail bed. A single streak is typically less than 3 millimeters wide initially but gradually widens. Over time, it can crack or break the nail. One important warning sign is when the dark pigment spreads beyond the nail onto the surrounding skin, a feature called Hutchinson’s sign. Subungual melanoma is sometimes mistaken for a fungal infection or dried blood under the nail, so a streak that doesn’t grow out with the nail or doesn’t resolve over several weeks is worth getting checked.
Melanoma That Doesn’t Look Dark
Not all melanomas are dark brown or black. Amelanotic melanoma is a rare subtype that produces little or no pigment. It’s usually pink or light brown, making it easy to dismiss as a pimple, bug bite, or scar. Because it lacks the classic dark coloring, the standard ABCDE criteria don’t always apply. The most useful clue is persistence: inflammatory skin issues like bug bites or ingrown hairs normally clear up within about three weeks, but cancer doesn’t resolve on its own. A pink or flesh-colored bump or patch that sticks around and keeps changing warrants a closer look.
Melanoma vs. Common Benign Growths
Seborrheic keratoses are one of the most common spots people confuse with melanoma. These benign growths are flat, waxy, and painless. They often look like unusual scabs stuck to the skin’s surface. The key visual difference is texture and borders: seborrheic keratoses have a waxy, “pasted on” appearance with relatively defined edges, while melanomas tend to have irregular, jagged borders with color that bleeds into the surrounding skin. A seborrheic keratosis also stays consistent in appearance, while melanoma keeps evolving.
Normal moles are another source of confusion. A healthy mole is generally round or oval, one uniform color, smaller than 6 millimeters, and stable over time. The “ugly duckling” approach is helpful here: if one mole looks noticeably different from all the others on your body, it’s the one to watch.
Why Thickness Matters
Once melanoma is identified, the single most important factor in determining outcomes is how deep it has grown into the skin, measured in millimeters. A melanoma 1 millimeter thick or less is classified as stage 1A, the earliest and most curable stage. Between 1.1 and 2 millimeters reaches stage 1B or 2A, depending on whether the surface skin is broken (ulcerated). Tumors between 2.1 and 4 millimeters are stage 2A or 2B, and anything thicker than 4 millimeters is stage 2B or 2C. The thinner the melanoma at the time it’s removed, the better the chance of a cure. This is the practical reason early detection matters so much: catching it while it’s still thin changes everything.
What to Actually Look For
Rather than memorizing every subtype, focus on a few practical habits. Look for any spot that is asymmetric, multicolored, or has blurry or jagged edges. Pay attention to any mole or mark that has changed in the past few weeks or months. Check places you might overlook: between your toes, on the soles of your feet, under your nails, and behind your ears. For darker skin tones, pay particular attention to the palms, soles, and nail beds, where melanoma is most likely to develop.
Any skin spot that doesn’t heal, keeps growing, or looks different from everything else on your body is the one that deserves professional evaluation. Melanoma is highly treatable when caught early, and spotting it starts with knowing what to look for.