Melanoma typically appears as an unusual mole or spot with uneven color, irregular borders, and an asymmetrical shape. Most are larger than 6 millimeters (about the size of a pencil eraser), though they can start smaller. What makes melanoma tricky is that it doesn’t always look the same. It can be dark brown, multicolored, or even pink, and it can show up in places you’d never think to check.
The ABCDE Rule for Spotting Melanoma
The most widely used framework for identifying melanoma is the ABCDE rule, developed by the National Cancer Institute. Each letter describes a visual feature to watch for:
- Asymmetry: One half of the mole doesn’t match the other. Normal moles tend to be roughly symmetrical.
- Border: The edges are ragged, notched, or blurred rather than smooth and well-defined. Pigment may spread into the surrounding skin.
- Color: The color is uneven. You might see shades of brown, tan, and black within the same spot, sometimes with patches of white, gray, red, pink, or blue mixed in.
- Diameter: Most melanomas are larger than 6 millimeters wide (about 1/4 inch), though they can be smaller when first detected.
- Evolving: The spot has changed in size, shape, or color over the past few weeks or months. This is often the single most important warning sign.
A mole doesn’t need to hit all five criteria to be concerning. Any one of these features, especially rapid change, is worth getting checked. Normal moles do change over the course of years, but melanoma-related changes happen quickly, on the order of weeks to months rather than years.
How Melanoma Differs From Harmless Spots
The spot most commonly confused with melanoma is a seborrheic keratosis, a harmless growth that can appear dark, patchy, and slightly raised. Seborrheic keratoses tend to look waxy or scab-like with a “stuck on” appearance. They can be dark enough to look alarming, but they’re usually symmetrical and uniform in texture. Melanomas, by contrast, have uneven coloring and irregular, jagged borders. Even dermatologists sometimes can’t tell the difference by eye alone and need to take a small biopsy to confirm.
A dysplastic (atypical) mole is another lookalike. These moles share some features with melanoma, like irregular borders or mixed colors, but they’re benign. Having many atypical moles does increase your melanoma risk, so if your body is covered in odd-looking moles, establishing a baseline with a dermatologist through full-body photography or regular skin checks makes it easier to spot something new or changing.
Nodular Melanoma: The One That Breaks the Rules
Not all melanomas follow the ABCDE pattern. Nodular melanoma, which accounts for a significant share of thick melanomas at diagnosis, often looks like a raised, dome-shaped bump rather than a flat, irregular mole. It can be dark or skin-colored and tends to grow outward from the skin surface rather than spreading sideways first.
For this type, clinicians use the “EFG” rule: Elevated above the skin surface, Firm to the touch (more solid than soft), and Growing progressively over weeks or months. If you notice a new bump that feels firm and keeps getting bigger, that combination of features is a red flag even if the spot looks nothing like a typical flat melanoma.
Pink and Skin-Colored Melanoma
One of the most dangerous presentations is amelanotic melanoma, which lacks the dark pigment most people associate with skin cancer. Instead, it appears as a pink, red, or skin-colored spot. Because it doesn’t look “cancerous” to most people, amelanotic melanoma is frequently overlooked or mistaken for a pimple, scar, or irritated patch of skin. It’s often diagnosed at a later stage compared to darker melanomas for exactly this reason.
If you have a pink or reddish spot that persists for several weeks, doesn’t heal, and slowly changes in size, it deserves attention regardless of how harmless it appears.
Melanoma on Palms, Soles, and Nails
Acral lentiginous melanoma develops exclusively on the palms of the hands, soles of the feet, or under the nails. It’s the most common type of melanoma in people with darker skin tones, and it doesn’t follow the typical ABCDE appearance the way other melanomas do.
On the palms or soles, it usually shows up as an unevenly pigmented black or brown spot that looks different from the rest of your skin and grows over time. People frequently dismiss it as a bruise, blood blister, or wart. Many don’t seek care until the spot starts bleeding or becomes painful to walk on.
Under the nail, melanoma appears as a dark pigmented streak running from the cuticle to the tip of the nail. A single streak is often less than 3 millimeters wide initially but gets wider over time. One key warning sign is called Hutchinson’s sign: the pigment bleeds beyond the nail into the surrounding skin at the cuticle or nail fold. A dark line under one nail that wasn’t caused by trauma and doesn’t grow out with the nail over several months should be evaluated.
What Changing Looks Like in Practice
The “evolving” criterion is worth understanding in detail because it’s the feature that catches melanomas other criteria might miss. Change can mean a mole getting larger, but it can also mean a flat spot becoming raised, a single-color mole developing a second color, a smooth border becoming jagged, or a spot starting to itch, bleed, or crust over.
The speed of change matters. Moles naturally shift in appearance over years, gradually getting lighter or slightly larger as you age. That slow drift is normal. Melanoma-related changes happen in weeks to months. If you can look at a spot and notice it’s different from what it looked like a month or two ago, that pace of change is what separates a spot worth monitoring from one worth getting biopsied promptly.
Why Early Detection Changes the Outcome
Melanoma caught while it’s still confined to the skin has a five-year survival rate of 97.6%. Once it spreads to nearby lymph nodes, that drops to 60.3%. If it reaches distant organs, the five-year survival rate falls to 16.2%. The overall survival rate across all stages is 90.5%, largely because most cases are caught early.
The practical takeaway is that a melanoma found when it’s thin and localized is a very treatable cancer. The visual features described above exist specifically to help catch it at that stage. Knowing what to look for, and doing a quick self-check of your skin every month or so, is genuinely one of the most effective things you can do to protect yourself. Pay special attention to areas you don’t normally see: your back, the soles of your feet, between your toes, and under your nails.