The seven warning signs of skin cancer come from a clinical screening tool called the 7-point checklist, developed to help identify melanoma and other suspicious skin changes. The checklist divides warning signs into three major signs and four minor signs, each pointing to a lesion that needs professional evaluation. Understanding all seven can help you catch skin cancer early, when it’s most treatable.
The 3 Major Warning Signs
These carry the most weight in clinical screening. Any one of them on its own is reason to have a spot checked by a dermatologist.
- Change in size. A mole or spot that’s getting bigger over weeks or months is one of the strongest red flags. Growth can happen gradually or rapidly, so comparing a spot to how it looked a few months ago matters.
- Irregular shape or border. Healthy moles tend to be roughly symmetrical. If one half doesn’t match the other, or the edges look ragged, notched, or blurred rather than smooth, that’s a concern. Pigment that seems to spread or bleed into the surrounding skin is especially suspicious.
- Irregular color. A single uniform shade of brown is typical for a normal mole. Warning signs include a mix of brown, black, tan, white, gray, red, pink, or blue within the same spot. The more colors present, the more attention it deserves.
The 4 Minor Warning Signs
These are less predictive on their own but add up. When a spot has one or more minor signs alongside a major sign, the concern increases significantly.
- Diameter of 7 mm or more. That’s slightly larger than a pencil eraser. While melanomas can be tiny, size matters as a screening tool. A spot that’s grown past this threshold warrants closer inspection.
- Inflammation. Redness, swelling, or puffiness around a mole or lesion that isn’t explained by an injury or infection can signal that something underneath is triggering an immune response.
- Oozing or crusting. A spot that bleeds, scabs over, or develops a crust without being scratched or injured is behaving abnormally. This is especially relevant if the crusting happens repeatedly.
- Change in sensation. Itching, tingling, or tenderness in a mole that previously felt like nothing is a subtle but meaningful clue. Many people dismiss itch as dry skin, but persistent itch localized to a single spot is worth noting.
How This Relates to the ABCDE Rule
You may also encounter the ABCDE rule, which is the most widely taught self-check method in the United States. It overlaps heavily with the 7-point checklist but organizes the information differently: Asymmetry, Border irregularity, Color variation, Diameter (usually larger than 6 mm, about a quarter inch), and Evolving (any change over weeks or months). The National Cancer Institute uses this framework as its primary screening tool.
The 7-point checklist adds symptoms the ABCDE rule doesn’t cover, specifically inflammation, oozing or crusting, and changes in sensation. Those additions make the 7-point list particularly useful for spots that don’t look like a classic dark mole but are still behaving suspiciously.
What Skin Cancer Actually Looks Like
Skin cancer doesn’t always match the textbook image of a dark, irregular mole. The appearance varies depending on the type and your skin tone.
Melanoma is the most dangerous form and the one the 7-point checklist was designed to catch. It often shows multiple colors and irregular borders. But some melanomas, called amelanotic melanomas, have little or no pigment at all. They can appear pink, red, or skin-colored, which means they don’t trigger the usual “dark mole” alarm. Adding three additional red flags helps catch these: red coloring, raised texture, and recent change.
Basal cell carcinoma is the most common skin cancer. On lighter skin, it often looks like a firm, shiny, pink or red bump, sometimes with a dip in the center that scabs over and bleeds. It can also appear as a rough, scaly patch that feels different from the skin around it. On darker skin tones, these bumps tend to look brown, glossy black, or tan with a rolled border. A sore that heals and then returns, or never fully heals, is a hallmark sign.
Squamous cell carcinoma frequently shows up as a flat sore with a scaly crust, a firm bump, or a wart-like raised area. It can develop on old scars or chronic sores. On the lips, it may start as a rough, scaly patch that eventually opens. The color varies widely: pink, red, brown, black, or the same shade as your surrounding skin.
Signs That Are Easy to Miss on Darker Skin
Most skin cancer images online show lesions on light skin, which creates a real detection gap. On darker skin tones, the most common melanoma type is acral lentiginous melanoma, which doesn’t develop on sun-exposed areas at all. It appears on the palms of the hands, the soles of the feet, under fingernails and toenails, and on fingers and toes. It can look like a dark patch on your palm or sole, or a dark band running lengthwise under a nail.
Basal cell and squamous cell carcinomas also look different on darker skin. They’re more likely to appear brown, black, or skin-colored rather than the classic pink or red. Because these colors blend more easily with surrounding skin, they’re often caught later. Checking areas that don’t get sun exposure, including your feet, nail beds, and palms, is especially important.
The “Ugly Duckling” Sign
Beyond checklists, one of the most intuitive screening methods is simply looking for the outlier. If you have many moles or freckles, most of them probably share a similar look. The “ugly duckling” is the one that doesn’t match: it’s scabbed when the others aren’t, it’s grown when the others haven’t, or it’s more raised than the rest. That mismatch, even if the spot doesn’t check every box on a formal checklist, is worth getting evaluated.
How to Use These Signs Practically
A monthly self-check is the simplest way to catch changes early. You’re not trying to diagnose anything. You’re looking for change. Use your phone to photograph moles or spots that you want to track, and compare them month to month. Pay attention to the soles of your feet, between your toes, your scalp, behind your ears, and your nail beds, since these are spots people tend to skip.
An estimated 112,000 new melanoma cases will be diagnosed in the U.S. in 2026 alone, and that doesn’t include the far more common basal cell and squamous cell cancers. Early-stage melanoma that’s still localized to the skin has a dramatically better prognosis than melanoma that has spread. The difference between those outcomes often comes down to catching a suspicious spot weeks or months sooner.
If a spot on your skin hits any of the major signs on the 7-point checklist, or combines a couple of minor signs, a dermatologist can evaluate it quickly. Most suspicious spots turn out to be benign, but the ones that aren’t are far easier to treat when they’re found early.