Melanoma typically appears as an unusual mole or spot with irregular shape, uneven color, and blurred or ragged edges. It can be brown, black, tan, or sometimes pink or red, and most are larger than 6 millimeters (about the size of a pencil eraser). But melanoma doesn’t always look the way you’d expect, and some forms break the usual rules entirely.
The ABCDE Rule
The most widely used framework for spotting melanoma is the ABCDE rule, which describes five features common in early melanoma:
- Asymmetry: One half of the mole doesn’t match the other. A normal mole is roughly symmetrical. If you drew a line down the center of a melanoma, the two sides would look noticeably different.
- Border: The edges are ragged, notched, or blurred rather than smooth and well-defined. The pigment may spread or fade into the surrounding skin.
- Color: Instead of one uniform shade, melanoma often contains a mix of colors. You might see brown, tan, and black within the same spot, sometimes alongside areas of white, gray, red, pink, or blue.
- Diameter: Most melanomas are larger than 6 millimeters wide, roughly the size of a pencil eraser. That said, melanomas can be smaller than this, especially when caught early.
- 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.
These criteria work well for the most common type, superficial spreading melanoma, which tends to grow outward across the skin surface before growing deeper. Early on, it looks like a flat or slightly raised patch with irregular color and shape. Over time it may become thicker, develop a bumpy or uneven surface, or start to bleed or itch.
How Early Melanoma Differs From Advanced
The earliest form, called melanoma in situ, is confined entirely to the top layer of skin. It looks like a flat, irregularly colored patch. At this stage, the spot tends to have a relatively simple appearance under magnification, with fewer internal structures visible.
As melanoma becomes invasive and starts growing deeper, the visual complexity increases. Dermoscopy studies show that invasive melanomas are significantly more likely to contain irregular dots or clusters of pigment, a blue-white veil (a hazy whitish-blue film over part of the lesion), and visible red or pinkish areas caused by new blood vessel growth. Roughly three-quarters of thin invasive melanomas show that blue-white veil, compared to about 40% of in situ lesions. These changes reflect the tumor recruiting its own blood supply and pushing deeper into the skin.
More advanced melanomas can become raised, firm, or nodular. They may ulcerate, meaning the surface breaks down and bleeds or crusts over. Some develop satellite spots, small new pigmented areas near the original lesion.
Nodular Melanoma Looks Different
Not all melanomas follow the ABCDE pattern. Nodular melanoma, the second most common subtype, often appears as a raised, dome-shaped bump rather than a flat spreading patch. It can be evenly shaped and may even have a regular border, which means it can pass the standard ABCDE test while still being dangerous.
Because nodular melanoma grows vertically into the skin rather than outward, it tends to progress quickly. The warning signs to watch for use a different shorthand: elevated, firm, and growing. The bump feels solid to the touch, and changes are noticeable over days or weeks rather than months. It can be dark brown or black, but it can also be skin-colored, pink, or red, making it easy to mistake for a pimple, cyst, or insect bite that won’t heal.
Melanoma Without Color
About 5% of all melanomas are amelanotic, meaning they produce little or no pigment. Instead of the dark brown or black spot most people picture, amelanotic melanoma appears as a pink, red, or skin-colored spot. It can look like a small sore, a pimple, or a patch of irritated skin.
Any subtype of melanoma can show up without pigment, including superficial spreading and nodular forms. Because it doesn’t look like what most people think of as a “suspicious mole,” amelanotic melanoma tends to be diagnosed at a later stage. If you have a pink or reddish spot that persists for several weeks, doesn’t heal, or slowly grows, it’s worth having a dermatologist examine it.
Melanoma on Hands, Feet, and Nails
Acral lentiginous melanoma develops on the palms, soles of the feet, fingers, toes, and under the nails. It’s the most common form of melanoma in people with darker skin tones, and it shows up in places many people never think to check.
On the palms or soles, it starts as a dark or brown discoloration that can look like a bruise or stain. Unlike a bruise, though, it doesn’t fade. Over time it grows in size and may develop irregular borders or uneven coloring.
Under a fingernail or toenail, this melanoma typically appears as a dark vertical streak or band running the length of the nail. It’s sometimes mistaken for blood under the nail or a fungal infection. As it progresses, the nail may crack or split, and pigment can spread into the skin around the nail. A key distinction: a bruise under the nail grows out with the nail over weeks, while a melanoma streak stays in place or widens.
Melanoma on Darker Skin
Melanoma is less common in people with darker skin but tends to be diagnosed later, partly because the warning signs look different and occur in less obvious locations. Rather than appearing as a changing mole on sun-exposed skin, melanoma in people with dark skin often shows up on the palms, soles, or nail beds.
It can also look like a dark or black bump that appears waxy or shiny. Because many darker-skinned individuals have more pigmented moles to begin with, the key is watching for the same evolution signals: a spot that’s changing, growing, or looks different from your other spots.
The Ugly Duckling Sign
Beyond examining any single spot for the ABCDE features, one of the most practical things you can do is compare your moles to each other. Most people have a “signature” mole pattern: their moles tend to look roughly similar in color, size, and shape. A melanoma often stands out as the outlier, the one spot that doesn’t look like the rest.
This is called the ugly duckling sign. The suspicious lesion might be larger, darker, lighter, or just visually “off” compared to its neighbors. An isolated spot with no similar moles nearby for comparison also counts as an ugly duckling and deserves a closer look. This approach is especially useful because it can flag melanomas that don’t neatly fit the ABCDE criteria, including small lesions, nodular types, and amelanotic forms.
Regression and Disappearing Color
Sometimes a melanoma partially destroys itself through a process called regression. This doesn’t mean the cancer is going away on its own. Visually, regression shows up as areas within a mole where color has faded or disappeared, leaving behind patches of white, gray, blue, or pink within an otherwise pigmented lesion. A mole that once had even coloring and now has pale or washed-out zones may be regressing, and this is considered a warning sign rather than a reassuring one.
What to Actually Look For
The practical takeaway is simpler than memorizing every subtype. You’re looking for any spot on your skin that is new and unusual, looks different from your other moles, or has changed in any way over recent weeks or months. Changes in size, shape, color, elevation, or texture all count. So do new symptoms in an existing mole: itching, burning, crusting, or bleeding.
Check your whole body, including places that don’t get sun exposure. Examine between your toes, on the soles of your feet, on your palms, and under your nails. Use a mirror or ask someone to look at your back and scalp. Taking photos of your moles every few months gives you a reliable comparison point, since it’s hard to notice gradual changes from memory alone.