Skin cancer shows up in several distinct ways depending on the type, and knowing what to look for can help you catch it early. The three main types, melanoma, basal cell carcinoma, and squamous cell carcinoma, each have their own visual signatures. A monthly self-check that covers your entire body, including spots you wouldn’t expect, is the most practical thing you can do at home.
The ABCDE Rule for Melanoma
Melanoma is the most dangerous form of skin cancer, but it’s also the one with the clearest set of warning signs. Dermatologists use the ABCDE framework, developed by the National Cancer Institute, to describe the features of early melanoma:
- Asymmetry: One half of the mole doesn’t match the other half in shape.
- Border: The edges are ragged, notched, or blurred rather than smooth. Pigment may spread into the surrounding skin.
- Color: Instead of a uniform shade, you see a mix of brown, tan, and black, sometimes with patches of white, gray, red, pink, or blue.
- Diameter: Most melanomas are larger than 6 millimeters (about the size of a pencil eraser), though they can be smaller.
- Evolving: The mole has changed in size, shape, or color over the past few weeks or months.
The “E” was added after the original criteria because research confirmed that change over time is one of the strongest signals. A mole that looked fine six months ago but now looks different deserves attention, even if it doesn’t tick every other box. And while 6 millimeters is still the standard diameter guideline, melanomas can occasionally be smaller, so size alone shouldn’t reassure you if other features are present.
The Ugly Duckling Sign
Beyond the ABCDE checklist, there’s a simpler pattern-recognition approach. Most of your moles tend to look like each other in color, size, and shape. If one mole clearly stands out from the rest, that’s what dermatologists call the “ugly duckling sign.” It’s the one that doesn’t belong, and it should raise suspicion even if it doesn’t meet every ABCDE criterion. This method is especially useful for people with many moles, where evaluating each one individually can feel overwhelming.
What Basal Cell Carcinoma Looks Like
Basal cell carcinoma is the most common skin cancer, and it rarely spreads to other parts of the body, but it can grow into surrounding tissue if left alone. It typically appears as a change in the skin that won’t heal, and it takes several forms:
- A shiny, translucent bump that looks pearly white or pink on lighter skin. On brown or Black skin, the bump often appears brown or glossy black. You may see tiny blood vessels running through it. It can bleed and scab over repeatedly.
- A dark lesion (brown, black, or blue) with a slightly raised, translucent border.
- A flat, scaly patch with or without a raised edge, which can grow quite large over time.
- A white, waxy, scarlike area without a clearly defined border.
The hallmark of basal cell carcinoma is a sore that cycles through bleeding and healing without ever fully resolving. If you have a spot that scabs over, seems to improve, then opens up again over weeks or months, that pattern alone is worth getting checked.
What Squamous Cell Carcinoma Looks Like
Squamous cell carcinoma is the second most common skin cancer. It often appears as a firm bump, a flat sore, a scaly patch, or a raised area on an existing scar. The color can vary: it may match your skin tone or appear pink, red, black, or brown. These lesions tend to show up on sun-exposed areas like the face, ears, neck, hands, and forearms, though they can also develop near the genitals, particularly in people who have been exposed to HPV.
Pre-Cancerous Patches to Watch
Actinic keratoses are rough, scaly patches that develop from years of sun exposure, and they’re worth knowing about because 5% to 10% of them eventually progress to squamous cell carcinoma. They typically appear on the head, neck, hands, and forearms, and they’re usually less than an inch across.
These patches can be flat or slightly raised, sometimes with a hard, wartlike surface. Colors range from pink to red to brown. They may itch, burn, bleed, or crust over. If you run your hand over sun-exposed skin and feel a rough, sandpapery patch that doesn’t go away, that’s the classic presentation. Catching and treating these early prevents them from becoming cancerous.
How Skin Cancer Appears on Darker Skin
Skin cancer looks different on darker skin tones, and these differences contribute to later diagnoses. Basal cell carcinoma can appear as a brown, glossy black, or tan bump with a rolled border. Melanoma may look like a dark or black bump that seems waxy or shiny. These variations mean the “pearly pink bump” description found in most guides doesn’t always apply.
The most common form of melanoma in people with dark skin is acral lentiginous melanoma, which develops in places that have little to do with sun exposure: the palms of the hands, the soles of the feet, and under the fingernails or toenails. It can look like a dark patch on your palm or the bottom of your foot, or a dark band running lengthwise under a nail. If a dark band under your nail begins to widen or spread, that’s a significant warning sign. Checking your nails, palms, and soles is especially important if you have darker skin.
Places Skin Cancer Hides
Most people check the obvious spots: arms, legs, face. But skin cancer develops in areas you might never think to look. Between your toes is one of the most commonly overlooked locations, and cancers there tend to be more advanced by the time they’re found simply because no one was looking. The scalp is another vulnerable area, particularly where you part your hair, since that strip of skin gets consistent sun exposure. People with lighter or thinning hair are at higher risk.
Eyelids, nail beds, the soles of your feet, your palms, your genitals, and the skin between your buttocks are all places where skin cancer can develop. These aren’t areas most people associate with sun damage, and some of them (like nail beds and soles) aren’t related to UV exposure at all.
How to Do a Full-Body Self-Check
A thorough self-exam takes about 10 minutes and works best right after a shower, in a well-lit room with a full-length mirror and a hand mirror. Do it once a month so you learn what’s normal for your skin and can spot changes quickly.
Start by facing the full-length mirror and scanning the front of your body: face, neck, chest, and abdomen. Raise your arms and check both sides of each arm, including the often-missed backs of your upper arms. Bend your elbows and inspect your forearms, then examine the tops and palms of your hands.
Turn around and use the hand mirror to see your back, the back of your neck, your buttocks, and the backs of your legs. Check the fronts of your legs, your genital area, and your feet, including the soles and the spaces between each toe. Use a comb to part your hair in sections and examine your scalp, or ask someone you trust to help with areas that are hard to see on your own.
What you’re looking for is anything new, anything that has changed, and anything that looks different from the spots around it. A new mole, a sore that doesn’t heal, a scaly patch that keeps coming back, a dark streak under a nail. Taking photos of moles you want to track makes it easier to notice subtle changes from month to month.
What Warrants a Professional Look
Any lesion that is actively changing in size, shape, or color should be evaluated. So should any sore that bleeds, crusts, or oozes and doesn’t heal within a few weeks. Itching or a change in sensation around a mole is another reason to get it examined. A rapidly enlarging bump, a new dark band under a nail, or any spot that clearly stands out as the ugly duckling among your other moles all deserve professional assessment.
There’s no universal recommendation for routine skin cancer screening by a doctor in people who have no symptoms. The U.S. Preventive Services Task Force says the evidence is currently insufficient to recommend for or against it. That means your own monthly self-checks are one of the most important tools available. If you have risk factors like a history of sunburns, fair skin, many moles, or a family history of melanoma, a dermatologist can help you decide on a screening schedule that makes sense for your situation.