Cancerous moles typically look uneven, multicolored, and irregular compared to normal moles, which tend to be round, uniform in color, and smaller than a pencil eraser (6 millimeters). While photos can help you compare, knowing exactly what visual features to look for is more reliable than matching your skin to a single image. Melanoma, basal cell carcinoma, and squamous cell carcinoma each have distinct appearances, and some dangerous skin cancers don’t look like “moles” at all.
The ABCDE Rule for Spotting Melanoma
The most widely used framework for identifying a suspicious mole is the ABCDE rule, developed to describe the visible features of early melanoma. Each letter flags a specific visual warning sign:
- Asymmetry: One half of the mole doesn’t match the other. A normal mole is roughly symmetrical. If you drew a line through the center of a melanoma, the two halves would look noticeably different in shape or thickness.
- Border irregularity: The edges are ragged, notched, or blurred rather than smooth and well-defined. Pigment may appear to “leak” or spread into the surrounding skin, creating a smudged look at the margins.
- Color variation: Instead of one uniform shade of brown, the mole contains multiple colors. You might see a mix of tan, dark brown, and black, or patches of white, gray, red, pink, or blue within the same spot.
- Diameter: Most melanomas are larger than 6 millimeters across, roughly the size of a pencil eraser. That said, melanomas can be tiny, so size alone doesn’t rule one out.
- Evolving: The mole has visibly changed over weeks or months. Any shift in size, shape, color, or texture is a red flag, as is new itching, pain, bleeding, or inflammation.
A normal mole is usually one color, has clean round or oval borders, and stays the same over time. If your mole checks multiple ABCDE boxes, that’s a stronger signal than hitting just one.
The “Ugly Duckling” Sign
Sometimes the most useful test isn’t examining one mole in isolation but comparing it to all the others on your body. If you have many freckles or moles, look for the one that doesn’t match the rest. Maybe it’s darker, more raised, scabbed over, or shaped differently from its neighbors. Dermatologists call this the “ugly duckling” sign, and it’s one of the most practical ways to catch a problem early. The mole that stands out from the crowd deserves a closer look.
Nodular Melanoma Looks Different
Not all melanomas spread outward across the skin first. Nodular melanoma grows downward, forming a raised, dome-shaped bump that can appear quickly. It follows a different set of visual cues known as the EFG criteria: elevated above the skin surface, firm to the touch, and growing over days to weeks rather than months. These can be dark brown or black, but they sometimes look pink or red, making them easy to dismiss as a pimple or bug bite. Their rapid growth is the key distinguishing feature.
Melanomas That Aren’t Dark
About 5 percent of melanomas are “amelanotic,” meaning they lack the dark pigment most people associate with skin cancer. These appear as pink, red, or skin-colored spots that can look like a harmless bump, a small sore, or even a pimple that won’t heal. Because they don’t match the typical image of a dark, irregular mole, amelanotic melanomas are frequently overlooked or confused with benign skin conditions, which often means they’re caught at a later, more advanced stage. If you have a pink or reddish spot that persists, grows, or bleeds without an obvious cause, it warrants attention even though it doesn’t look “cancerous.”
Melanoma in Hidden Locations
Melanoma doesn’t only show up on sun-exposed skin. Acral lentiginous melanoma appears on the palms of the hands, soles of the feet, and under fingernails or toenails. On the palms or soles, it typically looks like an unevenly pigmented black or brown spot that stands out from the surrounding skin and grows over time. Under a nail, it shows up as a dark pigmented streak or band running from the cuticle to the tip.
These melanomas are frequently mistaken for bruises, blood blisters, or warts, which delays diagnosis. Many people don’t seek care until the spot starts bleeding or becomes painful to walk on. A useful screening tool for these locations uses the acronym CUBED: colored lesion, uncertain diagnosis, bleeding, enlargement, and delay in healing. If a mark on your palm, sole, or nail bed matches several of those descriptors, it’s worth having a dermatologist examine it.
What Basal Cell Carcinoma Looks Like
Basal cell carcinoma is the most common form of skin cancer, and it doesn’t look like a mole at all. It often appears as a slightly translucent or pearly bump, almost like a small shiny dome on the skin. On lighter skin, the bump looks pearly white or pink. You may be able to see tiny blood vessels running across its surface. Some basal cell carcinomas show up as flat, scar-like patches or open sores that heal and then reopen. They grow slowly and rarely spread to other parts of the body, but they can damage surrounding tissue if left alone.
What Squamous Cell Carcinoma Looks Like
Squamous cell carcinoma can take several forms. It may appear as a firm, raised nodule that’s the same color as the surrounding skin, or it can look pink, red, brown, or black depending on skin tone. Another common presentation is a flat sore with a thick, scaly, or crusty surface. On the lips, it often starts as a rough, scaly patch that eventually becomes an open sore. It can also develop as a new raised area on top of an old scar, or as a wart-like growth. The common thread is a spot that looks rough, crusty, or raw and doesn’t heal on its own.
Benign Growths That Mimic Skin Cancer
Seborrheic keratoses are among the most common harmless skin growths, and they can look alarming. They range in color from white to black, often appear patchy, and sometimes resemble unusual-looking scabs. They’re typically flat or slightly raised, waxy in texture, and painless. They can show up anywhere on the body and frequently darken with age, which is when people start worrying about melanoma.
The key differences: seborrheic keratoses tend to look “stuck on” to the skin’s surface, like a blob of candle wax, while melanomas grow from within the skin. Seborrheic keratoses stay stable over long periods, while melanomas change in size, shape, or color. A seborrheic keratosis is usually one or two shades of brown without the dramatic color variation (blue, red, white patches) seen in melanoma. Still, even experienced dermatologists sometimes need a biopsy to tell them apart, so if a growth concerns you, getting it checked is reasonable.
How to Check Your Own Skin
A monthly self-exam takes about 10 minutes. Stand in front of a full-length mirror and scan your body systematically: face, scalp (use a handheld mirror or ask someone to help), neck, chest, arms, hands (including between fingers and under nails), legs, feet (including between toes and soles), and your back with the help of a mirror or partner. You’re looking for any spot that fits the ABCDE criteria, any ugly duckling that doesn’t match your other moles, and any new or changing lesion that doesn’t heal within a few weeks.
Photographing your moles every few months gives you a visual record to compare against. Changes that happen gradually can be hard to notice in real time, but a side-by-side photo comparison makes them obvious. Pay extra attention to areas that get a lot of sun, but don’t skip hidden spots like your scalp, the spaces between your toes, and under your nails.