American Melanoma Institute · 5 min read
How to recognize a spot that could be melanoma, and what a doctor does from the first look through the biopsy result.
The American Cancer Society estimates that about 112,000 new melanomas will be diagnosed in the United States in 2026. When melanoma is found while still confined to the skin, the 5-year relative survival rate is above 99%. Once it has reached distant organs, that figure falls to roughly 35%. Those 2 numbers explain why doctors spend so much time teaching people what to look for.
Dermatologists use 5 letters to describe the features that separate many melanomas from ordinary moles.
A spot does not need all 5 features to be worth showing to a doctor. DermNet, a dermatology reference written by physicians, notes that melanoma accounts for fewer than 3% of all changing skin spots. The checklist tells you which spots deserve a trained eye. Only a biopsy can make the diagnosis.
Most people's moles resemble one another, like members of a family. Doctors call a mole that looks different from all the rest the ugly duckling. It may be darker, lighter, larger, or smaller than its neighbors.
Melanoma often causes no sensation at all, so a painless spot gives no reassurance. When symptoms do appear, the American Cancer Society lists these as reasons to have a spot checked:
The Skin Cancer Foundation reports that about 20% to 30% of melanomas develop in an existing mole, while 70% to 80% arise on skin that looked normal before. A brand-new spot in an adult therefore deserves as much attention as a changing old one.
Melanoma also grows in places people rarely check: the scalp, the back, between the toes, the palms and soles, and under a nail, where it can appear as a dark streak. Some melanomas are pink or skin colored and fit none of the ABCDE rules. A raised, firm bump that keeps growing for more than a few weeks belongs on the list of spots to show a doctor, whatever its color.
The visit starts with questions. The doctor will want to know when you first noticed the spot, how it has changed, and whether anyone in your family has had melanoma.
Next comes the skin exam. Expect the doctor to look at far more than the one spot you came in for, and to feel the lymph nodes near it. Many dermatologists use a dermatoscope, a handheld magnifying lens with its own light, which shows pigment patterns under the skin surface that the naked eye can't see.
After this exam, many spots turn out to be harmless growths such as seborrheic keratoses or ordinary moles, and no further step is needed.
A biopsy is the only way to confirm or rule out melanoma. The doctor numbs the skin with a small injection and removes all or part of the spot.
For a suspected melanoma, the American Cancer Society describes the excisional biopsy as the preferred method. It removes the entire spot with a thin rim of normal skin, which lets the pathologist measure the full depth. A punch biopsy uses a small circular blade to take a core through all the skin layers. A deep shave biopsy (also called a saucerization) scoops under the spot with a blade. When a spot is very large or sits on the face or a nail, the doctor may sample only part of it, which is called an incisional biopsy.
The sample goes to a pathologist, a physician who diagnoses disease under the microscope. If the cells are hard to classify, the pathologist may add special stains (immunohistochemistry) or molecular tests, or ask a colleague for a second opinion. These steps add days to the wait. They reflect care, and they say nothing about what the answer will be.
If the spot is melanoma, the report gives its thickness in millimeters, called the Breslow depth. Thickness is the measurement that guides nearly every later decision.
The usual next step is a wide excision, a second, larger surgery that removes the biopsy site with a margin of normal skin. Thicker tumors get wider margins. For very thin melanomas, this surgery is often the only treatment needed.
For melanomas thicker than about 1 mm, and for some thinner ones with higher-risk features, doctors often discuss a sentinel lymph node biopsy. The surgeon injects a tracer near the melanoma site, finds the first lymph node that drains that patch of skin, and removes it for testing.
Questions worth bringing to that conversation include the Breslow depth, whether the biopsy edges were clear, how wide the excision will be, and whether a sentinel node biopsy is being recommended and why.
