A cancerous mole typically looks different from your other moles and changes over time. The most reliable way to spot one at home is to look for five specific warning signs, known as the ABCDE features, and to pay attention to any mole that stands out from the rest. No self-check replaces a biopsy, which is the only way to confirm melanoma, but knowing what to look for can help you catch it early when it’s highly treatable.
The ABCDE Features of Melanoma
Dermatologists use a five-letter framework to describe the visual features of early melanoma. Each letter flags a specific trait worth watching for:
- Asymmetry: One half of the mole doesn’t mirror the other. Normal moles tend to be roughly symmetrical.
- Border: The edges are ragged, notched, or blurred rather than smooth. Pigment may appear to spread into the surrounding skin.
- Color: Instead of a single uniform shade, you see a mix of brown, tan, black, or even patches of white, gray, red, pink, or blue within the same mole.
- Diameter: The mole is larger than about 6 millimeters, roughly the size of a pencil eraser. That said, melanomas can be smaller than this, so size alone isn’t a reliable rule-out.
- Evolving: The mole has changed in size, shape, color, or height over the past few weeks or months. New symptoms like itching, bleeding, or scabbing also count.
A mole doesn’t need to check every box to be suspicious. Even one of these features, especially “evolving,” is enough reason to have it examined. Changes over weeks to months are particularly concerning, according to oncologists at MD Anderson Cancer Center.
The Ugly Duckling Sign
Beyond the ABCDE checklist, there’s a simpler instinct worth trusting: does the mole look like your other moles? Most of the moles on your body share a general “family resemblance” in color, size, and shape. A mole that stands out from its neighbors, whether it’s noticeably larger, darker, lighter, or just different in texture, is called an “ugly duckling.” A spot that sits alone on your skin with no surrounding moles for comparison also qualifies. This pattern-recognition approach catches melanomas that might not obviously fit the ABCDE criteria on their own.
Types That Don’t Follow the Usual Rules
Not all melanomas are dark, irregular spots. Nodular melanoma, one of the more aggressive forms, often grows as a raised, firm bump rather than a flat, spreading mole. It may be uniform in color and have smooth borders, so it can slip past the standard ABCDE checklist entirely. The warning signs for this type are different: elevated from the skin surface, firm to the touch, and growing rapidly, with visible changes in days to weeks rather than months.
Amelanotic melanoma is another exception. It appears pink or red rather than brown or black because it lacks the pigment most people associate with skin cancer. Because it looks so much like a harmless bump or irritated patch, it’s often diagnosed later than pigmented melanomas. If you have a new pink or red spot that persists and grows, treat it with the same suspicion you’d give a dark mole.
Benign Growths That Mimic Melanoma
Plenty of harmless skin growths can look alarming. Seborrheic keratoses are one of the most common look-alikes. These are waxy, slightly raised spots that often appear “stuck on” to the skin surface, almost like a drop of candle wax. They can be dark brown or black and sometimes develop a rough, scaly texture. Under magnification, they contain tiny cyst-like structures that melanomas lack. Still, some seborrheic keratoses look convincingly suspicious even to trained eyes, so getting a professional opinion is reasonable if you’re unsure.
Other benign moles can also darken, become raised, or develop hairs over time. These changes tend to happen slowly, over years to decades. The key distinction is speed: benign moles evolve gradually, while cancerous changes typically progress over weeks to months.
How to Do a Self-Exam
The American Academy of Dermatology recommends checking your skin regularly. You don’t need special equipment, just good lighting and a full-length mirror, with a hand mirror for hard-to-see areas like your back, scalp, and the soles of your feet.
Work systematically so you don’t miss anything. Check your face, ears, and neck first, then move to your chest, torso, and arms (including under the nails). Use the hand mirror to examine your back, buttocks, and the backs of your legs. Finish with your feet, including between the toes. The goal isn’t to diagnose anything yourself. It’s to build a mental map of what your moles normally look like so you notice when something changes. Taking photos of moles you want to track can make comparison easier over time.
Adults over 40 should pay particular attention to new moles. It’s uncommon for new moles to appear after this age, and existing moles generally shouldn’t be growing. A new or growing spot in midlife or later warrants a closer look.
What Happens at the Dermatologist
A dermatologist will examine suspicious spots using a dermatoscope, a handheld magnifying device with its own light source. This tool reveals structural details invisible to the naked eye, and it improves diagnostic accuracy by roughly 49% compared to looking at a mole without magnification. That said, the accuracy depends heavily on the examiner’s experience, so a dermatologist trained in dermoscopy is the right person for the job. Visual inspection alone, even by a doctor, is only about 60% accurate.
If a mole looks concerning under the dermatoscope, the next step is a biopsy. For suspected melanoma, dermatologists typically perform an excisional biopsy, which removes the entire mole along with a small margin of surrounding skin using a scalpel. This approach ensures the lab gets the full picture of the lesion’s depth and structure. The procedure is done under local anesthesia in the office and usually takes less than 30 minutes. You’ll have a small wound closed with stitches, and results typically come back within one to two weeks.
For spots more likely to be a basal or squamous cell carcinoma, a shave biopsy (removing the top layers with a blade) or punch biopsy (using a small circular tool to take a deeper core sample) may be used instead. The type of biopsy depends on what the dermatologist suspects and where the spot is located.
How Fast Melanoma Can Progress
Growth rate varies widely depending on the type. Metastatic melanomas have been documented to double in size in as little as 30 days, while basal cell carcinomas grow very slowly over months to years. Most dermatologists consider mole changes visible within weeks to months a cause for concern. The bottom line: don’t take a “wait and see” approach with a mole that’s actively changing. Earlier detection leads to thinner tumors, which directly translates to better outcomes.