Melanoma is a type of skin cancer, and it’s the most dangerous one. It starts in melanocytes, the cells that produce the pigment giving your skin its color. While other skin cancers like basal cell and squamous cell carcinoma are far more common, melanoma stands apart because of its ability to spread to other parts of the body. The good news: when caught early and still confined to the skin, the five-year survival rate is 100%.
How Melanoma Differs From Other Skin Cancers
Not all skin cancers behave the same way. Basal cell carcinoma, the most common type, rarely spreads beyond its original site and has an excellent prognosis. Squamous cell carcinoma can occasionally spread but is still highly treatable in most cases. Melanoma is a different story. It is one of the most lethal malignancies, with a high chance of regional and distant spread if not caught early.
That distinction matters because it changes the urgency. A basal cell carcinoma found on your nose is serious and needs treatment, but it’s unlikely to threaten your life. A melanoma of similar size could potentially send cancer cells to your lymph nodes, lungs, liver, or brain if left untreated. This is why early detection is so critical for melanoma specifically.
What Melanoma Looks Like: The ABCDE Rule
The most widely used framework for spotting a suspicious mole is the ABCDE rule:
- Asymmetry: One half of the mole doesn’t match the other.
- Border: The edges are ragged, notched, or blurred, and pigment may spread into the surrounding skin.
- Color: The color is uneven, with shades of black, brown, and tan. You may also see areas 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.
Any single one of these features warrants a closer look. A mole that checks multiple boxes deserves prompt evaluation.
Forms That Are Easy to Miss
Not every melanoma follows the textbook pattern. Acral lentiginous melanoma appears on the palms, soles, fingers, toes, and under the nails, areas that get little sun exposure and that people rarely think to check. Under the nail, it often shows up as a dark streak running from the cuticle to the tip. A key warning sign is pigment spreading from the nail bed onto the surrounding skin of the cuticle or nail fold.
About 25% of these under-the-nail melanomas are amelanotic, meaning they show little or no dark pigment at all. They may look like a stubborn sore or a discolored patch that won’t heal. This makes them particularly easy to overlook or mistake for a fungal infection or injury. Melanoma on the soles of the feet is also commonly missed, especially in people with darker skin tones, for whom acral sites are a more common location for the disease.
The Four Main Subtypes
Melanoma isn’t one uniform disease. It takes several distinct forms, each with different growth patterns and typical locations.
Superficial spreading melanoma is the most common type. It grows slowly in a horizontal direction across the skin before pushing deeper. In women it tends to appear on the lower legs; in men, on the back. These are often caught as thinner lesions because the horizontal growth phase gives a wider window for detection.
Nodular melanoma is more aggressive. It develops over just weeks to months and grows vertically into the skin from the start, appearing as a dark, raised nodule. It’s most often found on the head, neck, and back in men, and on the legs in women. Because it skips the slow horizontal phase, it’s frequently diagnosed at a greater depth.
Lentigo maligna melanoma appears as a large, flat, irregularly bordered patch that grows very slowly. About 78% of cases occur on the head and neck, areas with years of accumulated sun exposure. It’s most common in older adults.
Acral lentiginous melanoma, described above, is the subtype found on palms, soles, and nail beds. It begins with a flat, spreading phase before eventually growing deeper into the tissue.
Survival Rates by Stage
How early melanoma is caught makes an enormous difference. National Cancer Institute data breaks down five-year survival by how far the cancer has spread at the time of diagnosis:
- Localized (confined to the skin): 100% five-year survival
- Regional (spread to nearby lymph nodes): 76% five-year survival
- Distant (spread to other organs): 34% five-year survival
The jump from localized to regional is striking. A melanoma that has only penetrated the skin layers is essentially curable with surgery alone, while one that has reached the lymph nodes requires more intensive treatment and carries meaningfully higher risk. This is why dermatologists emphasize regular skin checks and quick follow-up on anything that looks suspicious.
What Causes Melanoma
Ultraviolet radiation from the sun and tanning beds is the primary environmental driver. UV light damages the DNA in melanocytes, and over time those mutations can trigger uncontrolled cell growth. But genetics play a significant role too. About 38.5% of melanomas carry a mutation in the BRAF gene, which normally helps regulate cell growth. When that gene malfunctions, cells can multiply without the usual brakes. Another 16% carry mutations in NRAS, a different growth-signaling gene.
These genetic details matter practically because they determine treatment options if the cancer does advance. Targeted therapies exist that specifically block the effects of a BRAF mutation, which is why tumor samples are routinely tested for these markers.
Fair skin, a history of blistering sunburns (especially in childhood), a large number of moles, and a family history of melanoma all increase your risk. But melanoma can occur in anyone, including people with darker skin tones, where it tends to appear in acral locations or mucosal surfaces.
How Melanoma Is Diagnosed
If a dermatologist spots a suspicious lesion, the preferred approach is an excisional biopsy, which means removing the entire mole along with a small margin of surrounding skin and a layer of fat beneath it. This gives the pathologist the complete picture: whether it’s melanoma, how deep it has grown (measured as Breslow thickness), and whether the edges are clear of cancer cells. All of those details determine what happens next.
Punch biopsies and shave biopsies, which only sample part of the lesion, are not recommended for suspected melanoma because they can miss the deepest portion of the tumor. Without seeing the base, a pathologist can’t accurately measure how far the cancer has invaded. The exception is large lesions in cosmetically sensitive areas like the face, where removing the whole thing upfront may not be practical. In those cases, a partial biopsy of the most concerning area can be a reasonable first step.
Reducing Your Risk
Routine sunscreen use cuts melanoma risk substantially. Research tracking sun protection habits over two decades found that people who used sunscreen consistently had a 56% lower likelihood of developing melanoma compared to those who didn’t. That’s not occasional beach-day application. It’s daily, habitual use over years.
Other sun protection methods, like wearing hats, seeking shade, and covering up with clothing, were associated with a 41% reduction in melanoma risk. The strongest protection comes from combining these strategies rather than relying on any single one. Avoiding tanning beds is equally important, as artificial UV exposure carries the same DNA-damaging effects as natural sunlight, often at higher intensity.
Monthly self-exams are a practical habit. Check your entire body, including your scalp, between your toes, and the soles of your feet. Use a mirror for hard-to-see areas like your back. If you notice a new mole, a mole that’s changing, or a spot that looks different from everything else on your skin, get it evaluated promptly. The difference between localized and regional melanoma can be a matter of months.