Melanoma is a type of skin cancer that develops in the cells responsible for skin color. Its symptoms often start as changes in an existing mole or the appearance of a new, unusual spot on the skin. When caught early (stage I or II), the five-year survival rate is 97.6%. When it spreads to distant parts of the body, that number drops to 16.2%. Knowing what to look for makes a real difference.
The ABCDE Rule for Spotting Melanoma
The most widely used framework for evaluating a suspicious mole is the ABCDE rule, developed 40 years ago and still the global standard for initial screening. Each letter describes a specific warning sign:
- Asymmetry: One half of the mole doesn’t match the other. Most normal moles are roughly symmetrical.
- Border irregularity: The edges are ragged, notched, or blurred rather than smooth. The pigment may seem to spread or fade into the surrounding skin.
- Color variation: The mole isn’t one uniform shade. You might see a mix of brown, tan, black, or even patches of white, gray, red, pink, or blue within the same spot.
- Diameter: Most melanomas are larger than 6 millimeters across, roughly the size of a pencil eraser. That said, melanomas can be smaller, so size alone isn’t a reason to dismiss a suspicious spot.
- Evolving: The mole has changed in size, shape, or color over the past few weeks or months. Any noticeable change is worth attention.
A mole doesn’t need to check every box. Even one or two of these features is reason enough to have it evaluated.
The “Ugly Duckling” Sign
The ABCDE rule evaluates a single mole in isolation. The ugly duckling sign takes the opposite approach: it compares a spot to all the others on your body. Most of your moles tend to look similar to each other. The one that stands out, the spot that looks nothing like the rest, is the one most likely to be suspicious. These two methods complement each other. A mole that passes the ABCDE test might still be the ugly duckling, and vice versa. Using both together gives you the best chance of catching something early during a self-exam.
Secondary Physical Symptoms
Beyond visual changes, a melanoma can produce physical sensations that a normal mole typically doesn’t. New itching in a mole that was previously painless is one common signal. Bleeding, oozing, or crusting that doesn’t heal is another. Some melanomas become tender or inflamed. These symptoms don’t always mean cancer, but a mole that starts itching, bleeding, or forming a scab deserves prompt evaluation, especially if it’s also showing any ABCDE features.
Nodular Melanoma Looks Different
Not all melanomas spread outward across the skin surface first. Nodular melanoma grows downward into the skin from the start, making it more aggressive and harder to catch with the standard ABCDE criteria. It often appears as a raised, dome-shaped bump rather than a flat, irregularly shaped spot.
For this type, a separate set of warning signs applies, known as the EFG rule:
- Elevated: The lesion is raised above the skin surface. While plenty of benign bumps are also raised, a new elevated spot that wasn’t there before warrants attention.
- Firm: It feels solid or hard when pressed, unlike the soft give of a normal mole.
- Growing: It enlarges noticeably over days to weeks. Normal moles stay stable or change very slowly over years. Rapid growth is one of the most reliable red flags.
Nodular melanomas can be dark brown or black, but they can also be pink, red, or skin-colored, which makes them easy to mistake for a pimple or insect bite that won’t go away.
Melanoma Without Color
Most people picture melanoma as a dark, pigmented spot. But amelanotic melanoma produces little to no pigment, and it can catch people off guard. These lesions often appear as pink, red, or flesh-colored bumps. Some look like pearly nodules, others like non-healing ulcers or bleeding red bumps. In a series of cases reviewed in the medical literature, half of amelanotic melanomas presented as reddish spots and some appeared as yellow plaques. Descriptions ranged from “bleeding non-healing ulcer” to “rapidly enlarging yellow nodule.”
Because they lack the dark color people associate with melanoma, these lesions are frequently mistaken for other conditions. Any new bump that bleeds repeatedly, won’t heal, or keeps growing over weeks, even if it’s pink or colorless, should be checked.
Symptoms on Darker Skin Tones
Melanoma in people with darker skin often shows up in places that get little sun exposure: the palms of the hands, soles of the feet, and under fingernails or toenails. This type, called acral lentiginous melanoma, appears as an unevenly pigmented black or brown spot on the palm or sole that looks distinctly different from the surrounding skin and grows over time.
When it develops under a nail, it typically shows up as a dark streak or band of color running from the cuticle to the tip of the nail. The streak may widen over time, and pigment can spread into the skin surrounding the nail, which is a particularly telling sign. This type of melanoma is proportionally more common in Black, Hispanic, and Asian populations, and it’s often diagnosed later because people aren’t checking these areas.
Melanoma Beyond the Skin
Melanoma doesn’t always start on the outer skin. Uveal melanoma develops inside the eye and may first appear as a dark spot on the iris, the colored ring around your pupil. It can also cause blurred vision, flashing lights, or a gradual loss of peripheral vision. Routine eye exams can catch it before symptoms become obvious.
Mucosal melanoma forms on the moist lining tissues inside the body. It can develop as dark, irregular patches in the mouth, nasal passages, or genital area. Because these locations aren’t visible during a typical skin check, mucosal melanomas are often found at a more advanced stage.
Who Needs to Be Most Vigilant
Some people carry a higher baseline risk, which means even subtle mole changes deserve closer attention. Having a large number of moles is one of the strongest risk factors, with the total count mattering more than the size of individual moles. People with atypical mole syndrome (characterized by many irregular-looking moles, often with a family history of melanoma) face a 10.7% risk of developing melanoma over 10 years, compared to 0.62% in the general population. When two or more close family members have both atypical moles and melanoma, the lifetime risk approaches nearly 100%.
A weakened immune system also raises risk. This includes organ transplant recipients on immune-suppressing medications and people with certain blood cancers. A personal history of melanoma is another significant factor, which is why some clinicians advocate expanding the ABCDE rule to ABCDEF, with “F” standing for family or personal history. If you fall into a higher-risk category, the threshold for getting a spot checked should be lower. A mole that might be “probably fine” for someone with few risk factors is worth a closer look for you.