If a mole is cancerous, the next steps depend on the type of skin cancer and how deep it has grown. The good news: when melanoma, the most serious form, is caught while still confined to the skin, the five-year survival rate is above 99%. Even a mole that looks suspicious may turn out to be benign after testing. Here’s what to expect from the first warning signs through diagnosis, treatment, and beyond.
Signs That a Mole May Be Cancerous
Dermatologists use a set of five visual features, often called the ABCDE rule, to spot moles that need a closer look:
- Asymmetry: One half of the mole doesn’t match the other.
- Border irregularity: The edges are ragged, notched, or blurred rather than smooth and round.
- Color variation: Instead of a single shade of brown, you see a mix of brown, black, tan, white, red, pink, or blue.
- Diameter: The mole is larger than about 6 millimeters (roughly the size of a pencil eraser), though melanomas can be smaller.
- Evolving: The mole has changed in size, shape, or color over recent weeks or months.
Not every mole with one of these features is cancer, and not every skin cancer follows these rules neatly. Nodular melanoma, for instance, can appear as a small, dome-shaped bump that doesn’t look like a typical irregular mole. The most reliable warning sign is change. A mole that looks different from how it looked a few months ago deserves attention.
What Happens During the Biopsy
A mole can’t be diagnosed as cancerous just by looking at it. The only way to know for sure is a biopsy, where a sample of skin is removed and examined under a microscope. The procedure is done under local anesthesia in a doctor’s office and typically takes just a few minutes.
For a suspected melanoma, the preferred approach is an excisional biopsy, meaning the entire visible mole is removed along with a thin margin of normal skin beneath it. This gives the pathologist the full depth of the lesion, which is critical for accurate staging. For moles in difficult locations or very large moles, a punch biopsy (a small cylindrical core of tissue) may be used instead. A shave biopsy, which skims a thin layer from the surface, is generally reserved for suspected non-melanoma skin cancers because it can miss deeper features.
Results usually come back within one to two weeks. If the mole is benign, no further treatment is needed. If it’s cancerous, the pathology report will contain details that guide everything that comes next.
Understanding Your Pathology Report
The single most important number in a melanoma pathology report is the Breslow depth: how far the cancer cells extend downward from the skin surface, measured in millimeters. This measurement is the strongest predictor of outcome and determines the treatment plan.
Thin melanomas (less than 0.8 mm deep with no ulceration) are classified as T1a and carry an excellent prognosis. Between 0.8 and 1.0 mm, or any thin melanoma with ulceration (broken skin over the tumor), the classification shifts to T1b. As thickness increases through T2, T3, and T4 categories, the risk of the cancer having spread rises.
The report will also note whether the tumor is ulcerated and may include information about the rate at which cells are dividing. Together, these details tell your care team how aggressively to treat and how closely to monitor you going forward.
Not All Skin Cancers Are Melanoma
Melanoma gets the most attention because it’s the most dangerous, but two other types of skin cancer are far more common. Basal cell carcinoma and squamous cell carcinoma both arise from different cells in the outer layer of skin and are generally much less likely to spread to other parts of the body.
Basal cell carcinoma often appears as a pearly or waxy bump, while squamous cell carcinoma tends to look like a firm, red nodule or a flat lesion with a scaly crust. Neither typically develops from an existing mole the way melanoma sometimes does. In about 10 to 30 percent of cases, melanoma arises from a pre-existing mole or pigmented spot; the rest appear as entirely new growths. Notably, in people with dark skin, melanoma most commonly appears on areas not typically exposed to the sun, like the soles of the feet and the palms of the hands.
Surgery to Remove the Cancer
If a biopsy confirms melanoma, the standard next step is a wider surgical excision. Even if the entire mole was removed during the biopsy, surgeons go back and take a larger margin of normal-looking skin around the site to make sure no microscopic cancer cells remain at the edges.
How much skin is removed depends on the Breslow depth. For melanomas less than 1 mm thick, a 1 cm margin around the original site is typical. For thicker tumors (1 mm and above), margins of up to 2 cm are used. Research has shown that margins larger than 2 cm on the trunk and extremities don’t improve outcomes. This surgery is usually done as an outpatient procedure, and the wound is closed with stitches. Recovery time depends on the location and size of the excision, but most people return to normal activities within a few weeks.
Checking the Lymph Nodes
For melanomas thicker than 1.0 mm (T2 and above), doctors typically recommend a sentinel lymph node biopsy. This procedure identifies the first lymph node where cancer cells would travel if they left the skin. A tracer is injected near the melanoma site, and the surgeon removes the one or two lymph nodes that pick up the tracer. If those nodes are clear, the cancer is very likely still localized. If cancer cells are found, it changes the staging and may mean additional treatment is needed.
For very thin melanomas (under 0.8 mm without ulceration), a lymph node biopsy is not routinely recommended because the risk of spread is extremely low. For melanomas between 0.8 and 1.0 mm, or thin melanomas with ulceration, the decision is made on a case-by-case basis.
Treatment Beyond Surgery
Most early-stage melanomas are cured with surgery alone. When the cancer has spread to nearby lymph nodes (regional disease) or to distant organs, additional treatments come into play.
Immunotherapy uses medications that help your immune system recognize and attack melanoma cells. These drugs have transformed outcomes for advanced melanoma over the past decade. They work by releasing the “brakes” that cancer puts on immune cells, allowing your body to mount a stronger response against the tumor.
About 40 to 60 percent of melanomas carry a specific genetic mutation (in the BRAF gene) that fuels tumor growth. If testing shows this mutation is present, targeted therapy drugs can block that growth signal directly. These are typically taken as pills and are often combined in pairs to improve effectiveness and reduce the chance of resistance. For the roughly 40 percent of melanomas without this mutation, immunotherapy is the primary option for advanced disease.
Survival Rates by Stage
Melanoma survival rates are strongly tied to how far the cancer has spread at the time of diagnosis. Based on data from patients diagnosed between 2015 and 2021:
- Localized (confined to the skin): greater than 99% five-year survival
- Regional (spread to nearby lymph nodes): 76% five-year survival
- Distant (spread to other organs): 35% five-year survival
The overall five-year survival rate across all stages is 95%, reflecting the fact that most melanomas are caught early. Tumor thickness remains the single strongest factor in predicting outcome. Other factors that influence prognosis include age at diagnosis, the location of the tumor on the body, whether the tumor is ulcerated, and sex (women tend to have slightly better outcomes than men at similar stages).
What Follow-Up Looks Like
After treatment, you’ll enter a surveillance schedule designed to catch any recurrence or new skin cancers early. For early-stage melanomas (stage IA through IIA), this means skin exams and physical checkups every 3 to 12 months for the first five years, then annually after that. For higher-stage melanomas, visits are more frequent: every 3 to 6 months for the first two years, then every 3 to 12 months for years three through five, with lifelong annual skin checks recommended from that point on.
During these visits, your doctor will carefully examine your skin and feel your lymph nodes. Having had one melanoma increases your risk of developing another, so regular self-checks between appointments matter. Get familiar with your moles and look for the same ABCDE features that flagged the first one. Photographs of your skin can help you track changes over time.