Melanoma typically appears as an unusual mole or spot that looks different from others on your skin, often with uneven color, irregular edges, and an asymmetrical shape. Most are larger than 6 millimeters (about the size of a pencil eraser), though they can be smaller. The key distinguishing feature is change: a spot that’s growing, shifting color, or evolving in any way over weeks or months deserves a closer look.
The ABCDE Rule for Spotting Melanoma
Dermatologists use a five-feature checklist to describe the warning signs of early melanoma. Not every melanoma will have all five, but any one of them is worth paying attention to.
- Asymmetry: One half of the spot doesn’t match the other. Normal moles tend to be roughly symmetrical.
- Border irregularity: The edges are ragged, notched, or blurred rather than smooth and well-defined. 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 spot.
- Diameter: Most melanomas are larger than 6 millimeters wide when diagnosed, though they can start smaller. Any mole that’s growing in size is concerning regardless of how big it currently is.
- Evolving: The spot has changed in size, shape, color, or texture over the past few weeks or months. This is often the single most useful clue.
The “Ugly Duckling” Sign
If you have many moles or freckles, you may find it hard to evaluate each one individually. In that case, look for the outlier. Most of your moles probably share a similar appearance: roughly the same size, color, and shape. A mole that clearly stands out from the rest, whether because it’s darker, larger, more raised, or scabbed over, is what clinicians call the “ugly duckling.” That one spot that just doesn’t match the others is worth getting checked, even if it doesn’t obviously meet every ABCDE criterion.
Flat, Spreading Melanoma
The most common type is superficial spreading melanoma, which starts as a slowly growing flat patch of discolored skin. It can appear anywhere on the body but is most frequent on the trunk in men and the legs in women. Early on, it looks like an irregularly shaped, asymmetrical patch with smudgy or ill-defined borders. The color tends to be uneven, mixing light brown, dark brown, black, blue, gray, pink, or red within the same lesion. Some areas within the patch may be skin-colored or show white spots where the melanoma has partially regressed, which can make it look even more irregular.
Because this type grows outward across the skin surface before growing deeper, it often stays flat for months or even a couple of years. That slow initial phase is actually an advantage: it gives you more time to notice the changes.
Raised, Dome-Shaped Melanoma
Nodular melanoma looks very different from the flat spreading type. It appears as a firm, dome-shaped bump that’s usually hard to the touch. Colors range from dark brown or black to blue-black, red, or pink. Some are the same color as your surrounding skin. The texture can be smooth, crusty, or rough (sometimes described as cauliflower-like), and it can resemble a blood blister.
This type is more dangerous because it grows downward into the skin quickly rather than spreading outward first. It may not follow the ABCDE pattern neatly since it can be symmetrical and uniform in color. If you notice a new, firm bump on your skin that’s growing over a few weeks, that rapid change alone is a red flag.
Melanoma on Palms, Soles, and Nails
Acral lentiginous melanoma develops in places people rarely think to check: the palms of the hands, soles of the feet, and under fingernails or toenails. On the palms or soles, it appears as a black or brown discoloration that can resemble a bruise or stain. The key difference from an actual bruise is that it doesn’t fade over time. Instead, it slowly grows larger.
Under the nails, this type (called subungual melanoma) shows up as dark vertical streaks or bands running the length of the nail. It’s often mistaken for a fungal infection or dried blood under the nail. As it progresses, it can cause the nail to crack, break, or lift away from the nail bed. This subtype is more common in people with darker skin tones, who are less likely to develop melanoma on sun-exposed areas but face the same risk on these hidden surfaces.
Melanoma That Isn’t Dark
One of the most easily missed forms is amelanotic melanoma, which lacks the dark pigment most people associate with skin cancer. Instead of a brown or black spot, it appears as a pink or red patch on the skin. It can look like a pimple, a scar, or an irritated bump, which is why it often goes undiagnosed longer than pigmented types.
Because it doesn’t look “dangerous” in the traditional sense, amelanotic melanoma is a good reason to pay attention to any new or persistent skin irregularity, not just dark-colored ones. A pink spot that won’t heal, keeps growing, or feels different from the skin around it warrants evaluation.
How to Tell Melanoma From Harmless Spots
Several benign skin growths can look alarming. Seborrheic keratoses, the waxy, stuck-on-looking bumps that become more common with age, are among the most frequently confused with melanoma. Both can appear dark and irregularly shaped. Under magnification, seborrheic keratoses tend to show tiny cyst-like structures and pore-like openings within the lesion. Melanomas lack those features and instead display structural patterns visible only with a dermatoscope, which is one reason a professional evaluation matters when you’re unsure.
A few practical distinctions can help at home. Normal moles are usually one color, symmetrical, and stable over time. Seborrheic keratoses often look like they’ve been stuck onto the skin surface and have a rough, waxy texture. Melanoma, by contrast, tends to show multiple colors, irregular borders, and most importantly, visible change. If a spot on your skin is doing something new, growing, darkening, bleeding, itching, or changing shape, that evolution is the most reliable signal that it needs professional attention.
How Fast Melanoma Changes
The speed of visible change depends on the type. Superficial spreading melanoma can evolve gradually over months, slowly shifting in color or creeping outward. Nodular melanoma is more aggressive, sometimes growing noticeably within just a few weeks. In general, any mole or spot that looks different from how it looked a month or two ago is changing fast enough to take seriously. Taking photos of spots you’re monitoring, with a ruler or coin next to them for scale, gives you an objective way to track changes rather than relying on memory.