Melanoma typically appears as an unusual mole or dark spot on the skin that stands out because of its uneven shape, mixed colors, or irregular edges. It can look very different depending on the type, ranging from a flat brown patch with blurry borders to a firm, dome-shaped bump that resembles a blood blister. Knowing what to look for helps you catch it early, when treatment is most effective.
The ABCDE Features of Early Melanoma
The most widely used framework for spotting melanoma is the ABCDE rule, developed by the National Cancer Institute. Each letter flags a specific visual warning sign:
- Asymmetry: One half of the mole doesn’t match the other. Normal moles tend to be roughly symmetrical.
- Border irregularity: The edges look ragged, notched, or blurred rather than smooth and well-defined. Pigment may seem to spread or bleed into the surrounding skin.
- Color variation: Instead of one uniform shade, you see a mix of brown, tan, and black, sometimes with patches of white, gray, red, pink, or blue within the same spot.
- Diameter: Most melanomas are larger than 6 millimeters across (about the width of a pencil eraser), though they can be smaller when first developing.
- Evolving: The spot has visibly changed in size, shape, color, or texture over recent weeks or months.
Not every melanoma will check all five boxes. A spot that clearly meets even one or two of these criteria, especially “evolving,” deserves a closer look from a dermatologist.
The Most Common Type: Flat and Spreading
Superficial spreading melanoma is the most frequently diagnosed form. It starts as a slowly growing or changing flat patch of discolored skin. Early on, the surface is smooth. Over time, part of the patch may thicken and become raised while the rest stays flat, creating an uneven texture you can feel with your fingertip.
The borders are often ill-defined and smudgy in places rather than sharply outlined. Color tends to be uneven, with darker and lighter zones within the same lesion. Because it grows outward along the skin’s surface before pushing deeper, this type gives you a wider window to notice changes and act.
Nodular Melanoma: Raised and Firm
Nodular melanoma looks quite different from the flat, spreading type. It appears as a firm, dome-shaped growth that can be red, pink, brown, black, blue-black, or even the same color as your surrounding skin. The texture may be smooth, crusty, or rough (sometimes described as cauliflower-like), and it feels hard or firm when you press on it.
This type is often mistaken for a blood blister or a harmless bump. It grows downward into the skin faster than other melanomas, which makes recognizing it quickly more important. Because it doesn’t always follow the classic ABCDE pattern (it can be symmetrical, evenly colored, and smaller than 6 mm), any new, firm, dome-shaped growth that persists beyond a few weeks warrants attention.
When Melanoma Doesn’t Look Dark
Not all melanomas are brown or black. Amelanotic melanoma lacks the pigment most people associate with skin cancer, so it can appear pink, red, or skin-colored. A typical early lesion looks like an asymmetrical flat spot that is uniformly pink or red, sometimes with a faint ring of light tan, brown, or gray pigment around the edges.
Because it doesn’t fit the standard mental image of melanoma, amelanotic melanoma is frequently mistaken for a pimple, scar, or minor irritation. Dermatologists sometimes use the “3 R’s” alongside the ABCDE rule to catch these cases: Red, Raised, and Recent change. If you have a pink or red spot that is raised and appeared recently or keeps growing, treat it with the same seriousness as a dark mole.
Melanoma in Hidden Locations
Under the Nail
Subungual melanoma shows up as a dark, vertical streak running from the base of the nail to the tip. The streak is usually narrow at first (under 3 mm wide) but gradually widens over months. In more advanced cases, the pigment spreads beyond the nail onto the surrounding skin, a feature called Hutchinson’s sign. This type is more common on the thumb or big toe and occurs at higher rates in people with darker skin tones.
In the Eye
Melanoma can also develop inside the eye, most often in the layer beneath the white of the eye but sometimes as a growing dark spot on the iris (the colored part). Symptoms may include flashes of light, new floaters, a change in pupil shape, blurry vision in one eye, or loss of side vision. Many eye melanomas cause no symptoms at all and are found during routine eye exams.
The “Ugly Duckling” Test
Beyond examining individual moles, one of the most effective visual checks is the “ugly duckling” sign. Most of your moles tend to resemble one another in color, size, and shape. A melanoma often stands out as the one spot that simply looks different from all the rest.
In a study published in the Journal of the American Academy of Dermatology, this approach caught 86% of melanomas, and it worked nearly as well for non-clinicians (85% sensitivity) as it did for expert dermatologists (89%). All five melanomas in the study set were identified as obvious “ugly ducklings,” while only about 3% of benign moles triggered a false alarm. If one spot on your body looks nothing like its neighbors, that mismatch itself is a meaningful warning sign.
Melanoma vs. Harmless Lookalikes
Seborrheic keratoses are one of the most common benign growths mistaken for melanoma. They appear as waxy, flat or slightly raised spots that can be tan, brown, or nearly black. The key differences: seborrheic keratoses typically look “stuck on” the skin’s surface, have a uniform waxy texture, and stay the same over time. Melanoma, by contrast, tends to have irregular borders, uneven color, and visible change in size or shape over weeks to months.
If a growth that previously looked like a harmless keratosis starts changing in color, shape, or texture, that shift is exactly the kind of evolution that distinguishes melanoma from a benign spot.
Physical Sensations That Accompany Visible Changes
Melanoma isn’t always painless. As it progresses, a spot may start to itch, feel tender, or bleed without being bumped or scratched. Crusting or oozing can develop on the surface. These sensations don’t appear in every case, but new itchiness or spontaneous bleeding in a mole that is also changing visually adds another reason to have it evaluated promptly.
How Quickly Melanoma Changes
Growth rate varies widely. Some melanomas, particularly nodular types, can change noticeably within weeks to months. Others, like lentigo maligna melanoma (common on sun-damaged skin in older adults), can grow slowly over years or even decades. There is no reliable way to predict how fast a specific melanoma will progress, which is why any new or changing spot is worth checking sooner rather than later.