Melanoma typically appears as an unusual mole or spot that looks different from the rest of your skin. It may be dark brown or black with uneven coloring, irregular borders, and an asymmetric shape. But melanoma doesn’t always fit that description. Some forms are pink, red, or even skin-colored, and others show up under nails, on the soles of your feet, or inside your mouth. Knowing the full range of what melanoma can look like is what makes early detection possible, and early detection matters: when caught before it spreads, the five-year survival rate is essentially 100%.
The ABCDE Rule for Spotting Melanoma
Most dermatologists teach the ABCDE framework as a starting point for identifying suspicious spots. Each letter flags a specific visual warning sign:
- Asymmetry: One half of the mole doesn’t mirror the other. A normal mole is roughly symmetrical; melanoma tends to grow unevenly.
- Border irregularity: The edges look ragged, notched, or blurred rather than smooth and well-defined. Pigment may seem to bleed into the surrounding skin.
- Color variation: Instead of a single uniform shade, the spot contains a mix of brown, tan, and black. You might also see patches of white, gray, red, pink, or blue within the same lesion.
- Diameter: Most melanomas are larger than 6 millimeters across, roughly the size of a pencil eraser. That said, melanomas can be smaller, especially when caught early.
- Evolving: The spot has changed in size, shape, or color over recent weeks or months. Any mole that looks different from how it looked before deserves attention.
These criteria catch the majority of melanomas, particularly the most common type called superficial spreading melanoma. But not every melanoma checks all five boxes, and some dangerous forms break these rules entirely.
The “Ugly Duckling” Sign
Sometimes the most useful clue isn’t what a single mole looks like on its own, but how it compares to the moles around it. The ugly duckling sign refers to a spot that simply looks different from all the others on your body. Most people’s moles share a general family resemblance in color, size, and shape. If one mole stands out as the odd one, that outlier deserves a closer look, even if it doesn’t obviously meet the ABCDE criteria.
Flat vs. Raised: How Melanoma Changes Shape
In its earliest stage, melanoma is usually flat. It starts by spreading outward across the surface of the skin, staying confined to the outermost layer. During this phase it looks like a flat, irregularly shaped spot, and it’s the easiest time to treat.
Over time, genetic changes can push the cancer to grow downward into deeper tissue. When that happens, the melanoma becomes thickened, raised, and firm to the touch. A spot that was once flat and is now developing a bump or dome-shaped area is a serious warning sign. This transition from flat to raised often signals a more advanced and harder-to-treat stage.
Nodular Melanoma: The Fast-Growing Exception
Nodular melanoma skips the flat stage almost entirely. Instead of spreading outward first, it grows downward from the start, forming a firm, dome-shaped bump that develops rapidly over just weeks or months. It can look like a blood blister, a small round dome, or a raised sore. The surface may be smooth, crusty, or rough like cauliflower.
What makes nodular melanoma tricky is that it often doesn’t follow the ABCDE rules. It can be symmetrical and uniform in color. The more useful warning signs are that it’s elevated, firm to the touch, and actively growing. It may bleed, itch, or sting. Colors range widely: it can be red, pink, brown, black, blue-black, or even the same shade as your surrounding skin. Because it grows so quickly and can look like something harmless, nodular melanoma is frequently caught at a later stage.
Pink and Skin-Colored Melanoma
When most people picture melanoma, they think of a dark spot. Amelanotic melanoma breaks that expectation. It appears as a pink or red spot on the skin, sometimes with no dark pigment at all. It can look like a pimple, a scar, or an irritated patch of skin.
Because it doesn’t have the telltale dark coloring people associate with skin cancer, amelanotic melanoma is frequently mistaken for a harmless lesion. That confusion leads to later diagnoses on average compared to pigmented melanomas. If you have a pink or reddish spot that isn’t healing, is growing, or just seems “off,” it’s worth having it checked.
Melanoma Under Nails
Subungual melanoma develops under a fingernail or toenail and looks quite different from melanoma on exposed skin. The most common early sign is a dark vertical streak running from the base of the nail to the tip, as if someone drew a line with a brown or black marker. The streak typically starts out narrow, less than 3 millimeters wide, but gradually widens and may eventually cover the entire nail.
The coloring is often uneven, with varying shades of brown and black. As the melanoma progresses, it can cause the nail to crack, lift away from the nail bed, or develop a sore that bleeds. One particularly telling sign is when the dark pigment spreads beyond the nail onto the surrounding cuticle and skin. This is known as the Hutchinson sign, and it strongly suggests melanoma rather than a bruise or fungal infection, which are common lookalikes.
Melanoma on Palms, Soles, and Darker Skin
Acral lentiginous melanoma is the type most commonly found on the palms of the hands, soles of the feet, and under nails. It’s also the most common form of melanoma in people with darker skin tones, though it can affect anyone.
On the palms or soles, it appears as a black or brown discoloration that may initially resemble a bruise or a stain. Unlike an actual bruise, it doesn’t fade over time. Instead, it gradually grows larger. The borders are often irregular, and the color may be uneven. Because these locations aren’t spots people typically monitor for skin cancer, and because the early appearance can seem so benign, acral lentiginous melanoma is often caught later than other types.
Melanoma in the Mouth and Other Hidden Areas
Mucosal melanoma develops on moist tissue lining the inside of the body rather than on the skin’s surface. The most common locations are the nasal passages, lips, and mouth, followed by the anorectal area and the vulvovaginal region. These melanomas are rare but easily missed because they form in places you can’t see during a typical skin check.
In the mouth, mucosal melanoma may appear as a dark spot or lump on the tongue, gums, or inner cheek. It can also present as a sore that won’t heal, unexplained mouth bleeding, or dentures that suddenly fit poorly. In the nasal passages, it often causes repeated nosebleeds from one side or a persistent feeling of obstruction. In the anorectal area, it can look like a lump or cause bleeding, pain, or itching. On the vulva or in the vagina, signs include unusual bleeding, a visible growth, or persistent itching that doesn’t respond to treatment.
What Dermatologists See Up Close
When a dermatologist examines a suspicious spot with a dermatoscope (a magnifying tool with a built-in light), they look for features invisible to the naked eye. One of the strongest indicators of invasive melanoma is something called a blue-white veil: an area of hazy blue pigmentation with a whitish, frosted-glass film over it. This feature is highly specific to melanoma. Dermatologists also look for irregular pigment patterns, unusual dot and blotch structures, and other microscopic clues that help distinguish melanoma from a harmless mole.
This is worth knowing because it explains why a spot that looks “probably fine” to you might still warrant a professional evaluation with proper tools. The naked eye can only catch so much.
Why Timing Matters
The visual changes you notice, or miss, directly correlate with how treatable melanoma is. When melanoma is caught while still localized to the skin, the five-year survival rate is 100%. Once it spreads to nearby lymph nodes, that drops to 76%. If it reaches distant organs, the rate falls to 34%. The difference between these outcomes often comes down to recognizing a suspicious spot while it’s still flat, small, and confined to the surface. Regular self-checks that include your nails, the soles of your feet, and hard-to-see areas like your scalp and back give you the best chance of catching something early.