SpotCheck Clinical Staff
Moles are extremely common, and most are completely harmless. But melanoma—a dangerous form of skin cancer—can sometimes start in what looks like an ordinary mole. Knowing what to look for can help you catch concerning lesions early, when treatment is most effective.
Below is a practical, medically grounded guide on how to tell the difference.
Benign (noncancerous) moles—also called nevi—are clusters of pigment-producing cells. They often appear in childhood or early adulthood and may slowly change over time.
Typical features of a benign mole include:
Benign moles tend to look "organized," even if they're darker or raised.
Melanoma is a cancer of pigment-producing cells (melanocytes). It can grow quickly and spread if not treated early. While melanomas can arise in existing moles, most start as new spots on the skin.
Melanoma may look:
Even small melanomas can be dangerous, which is why early detection matters.
Doctors often use the ABCDE rule to help distinguish concerning lesions from benign moles.
Benign moles: One half mirrors the other.
Melanoma: The halves don't match.
Benign moles: Smooth, well-defined edges.
Melanoma: Edges may look jagged, blurred, or scalloped.
Benign moles: One uniform shade.
Melanoma: Multiple colors (brown, black, red, blue, white).
Benign moles: Typically smaller.
Melanoma: Often larger than 6 mm (a pencil eraser), but size alone isn't reliable—some melanomas are tiny.
The most important sign.
Any mole that is changing—growing, darkening, itching, bleeding—deserves prompt evaluation.
This rule can be just as helpful as the ABCDEs.
Most people have a "pattern" to their moles.
A lesion that looks different from all your other spots—darker, lighter, larger, odd-shaped—is the "ugly duckling."
This is often an early clue to melanoma.
You should see a dermatologist if you notice:
Trust your instincts—patients often spot melanoma because something looks off.
Melanoma can show up anywhere, including:
Don't forget to check these "hidden zones."
Some people develop irregular-looking moles that are still benign but mimic melanoma. Dermatologists usually monitor these with photos or periodic exams.
Melanoma is less common but more likely to appear in:
Any new dark streak in a nail should be evaluated.
If you're ever unsure, get it checked. A quick skin exam can offer peace of mind—and early detection saves lives.