Skin cancer doesn’t always look like what you’d expect. Melanoma, the most dangerous type, often resembles an unusual mole with uneven color, irregular borders, or a diameter larger than 6 millimeters (about the size of a pencil eraser). But other skin cancers can appear as pearly bumps, scaly patches, or sores that won’t heal. Knowing what to look for across all three major types gives you the best chance of catching something early.
Melanoma and the ABCDE Rule
Melanoma is the skin cancer most likely to develop in or near an existing mole, and the ABCDE rule is the standard framework for spotting it early.
- Asymmetry: One half of the mole doesn’t match the other. Normal moles are roughly symmetrical.
- Border: The edges are ragged, notched, or blurred rather than smooth. Pigment may spread into the surrounding skin.
- Color: Multiple shades appear within the same spot. You might see black, brown, and tan alongside areas of white, gray, red, pink, or blue. A normal mole is typically one uniform color.
- Diameter: Most melanomas are larger than 6 millimeters wide, though they can be smaller. Any mole that’s growing deserves attention regardless of size.
- Evolving: The mole has changed in size, shape, color, or texture over the past few weeks or months.
In more advanced melanoma, the surface of the mole may break down and look scraped. It can become hard or lumpy, and it may ooze, bleed, itch, or feel tender.
Nodular Melanoma Grows Fast
Not all melanomas spread outward first. Nodular melanoma grows downward into the skin rapidly, sometimes changing noticeably over days or weeks. It often appears as a raised, firm bump that can be dark brown, black, or even skin-colored. Because it doesn’t always follow the classic ABCDE pattern, a separate set of warning signs applies: the lesion is elevated, firm to the touch, and growing quickly. If you notice a new bump that feels solid and seems to be getting bigger fast, that’s reason enough to have it checked.
What Basal Cell Carcinoma Looks Like
Basal cell carcinoma is the most common skin cancer, and it rarely looks like a mole. On lighter skin, it typically appears as a slightly translucent or pearly bump that’s skin-colored or pink. You might notice tiny blood vessels running through it. On brown and Black skin, the same bump often looks brown or glossy black with a rolled border.
Basal cell carcinoma can also show up as a flat, scaly patch with a raised edge, a brown or blue lesion with dark spots and a translucent border, or a white, waxy, scar-like area without a clear boundary. These bumps sometimes bleed and scab over, then seem to heal, then bleed again. That cycle of bleeding and scabbing is a hallmark worth paying attention to.
What Squamous Cell Carcinoma Looks Like
Squamous cell carcinoma tends to appear on sun-exposed areas like the face, ears, hands, and lips. It can look like a firm nodule that’s pink, red, brown, or black depending on your skin tone. It can also appear as a flat sore with a scaly crust, a rough patch on the lip that becomes an open sore, or a wart-like bump that crusts or bleeds. A new sore or raised area developing on an old scar is another presentation. Unlike basal cell carcinoma’s pearly quality, squamous cell carcinoma tends to look rougher and more textured on the surface.
When Skin Cancer Has No Color
About 2% of melanomas produce little to no pigment. These amelanotic melanomas typically appear as pink to red spots or bumps rather than the dark brown or black lesions most people associate with skin cancer. Because they lack the obvious color changes described in the ABCDE rule, they’re easy to dismiss as a pimple, bug bite, or minor irritation. A pink or reddish bump that persists for weeks, doesn’t respond to typical treatments, or slowly grows is worth having evaluated.
Skin Cancer Under the Nails
Subungual melanoma shows up as a dark, vertical streak running from the base of the nail to the tip. The streak is usually blackish-brown with irregular, uneven pigment, and it tends to widen over time, especially at the base of the nail near the cuticle. In some cases, the discoloration spreads beyond the nail onto the surrounding skin, a feature called the Hutchinson sign that strongly suggests melanoma.
Not every dark line under a nail is cancer. People with darker skin tones commonly develop harmless pigmented bands in their nails. But a single streak that’s new, widening, or accompanied by nail cracking, lifting, bleeding, or swelling should be examined. Some nail melanomas don’t produce color at all and instead form a small nodule that lifts or damages the nail.
Skin Cancer on Palms, Soles, and Darker Skin
Acral lentiginous melanoma appears on the palms of the hands, soles of the feet, and under the nails. It’s the most common type of melanoma in people with darker skin tones, and it often goes undiagnosed because these are areas people don’t think to check. It typically looks like an unevenly pigmented black or brown spot that stands out from the surrounding skin and grows over time.
People frequently mistake it for a bruise, blood blister, or wart, which is why it’s often not caught until it starts bleeding or causes discomfort. The CUBED memory tool can help: look for unusual Color, an Uncertain diagnosis (it doesn’t clearly look like something benign), Bleeding, Enlargement, and Delay in healing. Any persistent dark spot on your palms or soles that doesn’t resolve in a few weeks deserves a closer look.
Normal Moles vs. Atypical Moles vs. Melanoma
A normal mole is round or oval, one uniform color (usually tan or brown), smaller than 6 millimeters, and has a smooth, distinct border. It looks the same month after month.
Atypical moles, sometimes called dysplastic nevi, sit in a gray zone. They’re usually wider than 5 millimeters, may have a mixture of pink, tan, and brown shades, and have irregular edges that fade into the surrounding skin. Their surface can be smooth, slightly scaly, or pebbly. Some have a raised center with a flat rim, giving them a “fried egg” appearance. Having atypical moles doesn’t mean you have cancer, but having many of them increases your melanoma risk.
Melanoma pushes further along the spectrum. The color variation is more dramatic, potentially including black, blue, white, or red. The borders are more ragged and notched rather than simply fading at the edges. And critically, melanoma changes, while an atypical mole that’s been stable for years is far less concerning than one that shifted in color or size last month.
The Ugly Duckling Sign
Beyond the ABCDE rule, one of the most practical ways to spot a problem is the “ugly duckling” sign. Most of your moles share a family resemblance. They tend to be roughly the same color, size, and shape. The ugly duckling is the one mole that looks nothing like the others. It stands out. That outlier, regardless of whether it checks every ABCDE box, is the one worth showing to a dermatologist. Sometimes the most useful screening tool is simply knowing what’s normal for your own skin and noticing when something breaks the pattern.