Melanoma typically shows up as a mole or spot that looks different from the others on your skin, either because it’s changed recently or because its shape, color, or size seems off. Most melanomas share a set of visible warning signs you can check at home, though some forms look nothing like a dark mole. Knowing what to look for, and where to look, can help you catch it early when treatment is most effective.
The ABCDE Rule
Dermatologists use five features to describe early melanoma, and they’re straightforward enough to check on your own skin:
- Asymmetry. One half of the spot doesn’t match the other. A normal mole is roughly symmetrical; melanoma often isn’t.
- Border. The edges are ragged, notched, or blurred rather than smooth. Pigment may seem to bleed into the surrounding skin.
- Color. The color is uneven. You might see a mix of brown, tan, and black, or patches of white, gray, red, pink, or blue within the same spot.
- Diameter. Most melanomas are larger than about 6 millimeters wide (roughly the size of a pencil eraser), though they can be smaller.
- Evolving. The spot has changed in the past few weeks or months. Any shift in size, shape, color, or texture counts.
Not every melanoma checks all five boxes. A spot that meets even one or two of these criteria is worth having a dermatologist examine, especially if it’s evolving.
The Ugly Duckling Sign
If you have many moles or freckles, there’s a simpler way to scan your skin: look for the one that doesn’t match the rest. Maybe it’s darker, more raised, scabbed over, or just visually different from its neighbors. Dermatologists call this the “ugly duckling” sign. Most of your moles tend to look similar to each other. The outlier, the one that stands apart from the pattern, deserves closer attention.
Melanoma That Doesn’t Look Like a Dark Mole
Not all melanomas are brown or black. Amelanotic melanoma appears as a pink or red spot on the skin, with little or no pigment. Because it doesn’t match what most people picture when they think of skin cancer, it’s easy to dismiss as a pimple, scar, or irritation. If you have a pink or reddish bump that doesn’t heal within a few weeks, that’s a reason to get it checked.
Nodular Melanoma
This aggressive type grows fast, usually over several weeks to months. It shows up as a firm, dome-shaped, raised 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 like cauliflower. It may bleed, itch, or sting. Nodular melanomas are typically larger than 1 centimeter across (about the length of a staple). Because they grow outward and downward quickly, they’re one of the most important types to catch early.
Melanoma on Palms, Soles, and Nails
Acral lentiginous melanoma develops in places people rarely think to check: the soles of the feet, the palms of the hands, and under fingernails or toenails. It appears as a black or brown discoloration that may resemble a bruise or stain but grows in size over time. This type occurs equally across all races and skin tones and accounts for the majority of melanoma diagnoses in people of color.
When it develops under a nail, it usually looks like a dark vertical streak running the length of the nail bed. The streak is often less than 3 millimeters wide initially but widens over time. As it progresses, the nail may crack or break. A key warning sign, called Hutchinson’s sign, is when the dark pigment spreads into the skin surrounding the nail. This type is frequently mistaken for a fungal infection or a blood blister under the nail, so new streaks that aren’t linked to an injury are worth showing a doctor.
How to Do a Skin Self-Exam
A monthly self-check is the simplest way to notice changes early. The best time is after a bath or shower, in a well-lit room with a full-length mirror.
Start by looking at the front and back of your entire body in the mirror. Raise your arms and check both sides, including the backs of your upper arms, which are hard to see. Bend your elbows and examine both sides of your forearms. Look at the tops and palms of your hands. Check your face, neck, and the back of your neck. Use a hand mirror and a comb to part your hair and inspect your scalp. Examine your chest, abdomen, and the front and back of both legs. Look at your buttocks, between your buttocks, and your genital area. Finally, sit down and check the soles of your feet, between your toes, and your toenails. Ask someone you trust to help with areas you can’t see well on your own.
The goal isn’t to diagnose anything yourself. It’s to build a mental map of what your skin normally looks like so you notice when something changes.
What Happens if Something Looks Suspicious
A dermatologist will first examine the spot visually, often using a handheld magnifying device called a dermatoscope. This tool reveals structures beneath the skin’s surface that aren’t visible to the naked eye, like irregular pigment patterns or a blue-gray veil over part of the lesion. These details help distinguish melanoma from harmless moles.
If the spot still looks concerning, the next step is a biopsy, which means removing some or all of the tissue so it can be examined under a microscope. There are a few ways this is done:
- Shave biopsy. A blade scrapes off the top layers of skin. No stitches are usually needed. This works for surface-level spots.
- Punch biopsy. A small circular cutting tool removes a deeper core of skin, including layers below the surface. Stitches may be needed depending on the size.
- Excisional biopsy. A scalpel removes the entire suspicious area along with a margin of normal skin around it. This typically requires stitches.
For a suspected melanoma, doctors generally prefer to remove the entire lesion when possible, because measuring its full depth is critical for determining how advanced it is. The procedure is done with local numbing and usually takes less than 30 minutes. Results typically come back within one to two weeks.
What Makes Someone Higher Risk
Certain factors increase your likelihood of developing melanoma: having more than 50 moles on your body, a history of severe sunburns (especially before age 18), fair skin that burns easily, a family history of melanoma, or a personal history of any skin cancer. People who use tanning beds also face elevated risk. But melanoma can develop in anyone regardless of skin tone, which is why self-exams matter for everyone. On darker skin, melanoma is more likely to appear in less sun-exposed areas like the palms, soles, and nail beds rather than on the back or legs.