Cancer spots on the skin don’t all look the same. They can appear as pearly bumps, scaly red patches, dark irregular moles, or sores that won’t heal, depending on the type of skin cancer. The key to spotting them early is knowing what each type tends to look like and watching for any spot that changes over time.
Melanoma: The Most Dangerous Type
Melanoma is the skin cancer most people worry about, and for good reason. It’s the most likely to spread to other organs. The classic way to spot it is the ABCDE rule developed by the National Cancer Institute:
- Asymmetry: One half of the mole doesn’t match the other.
- Border: The edges are ragged, notched, or blurred rather than smooth and round. Pigment may spread into the surrounding skin.
- Color: The spot has uneven color, with mixtures of black, brown, tan, white, gray, red, pink, or blue.
- Diameter: Most melanomas are larger than 6 millimeters (about the size of a pencil eraser), though they can start smaller.
- Evolving: The spot has changed in size, shape, or color over the past weeks or months.
Not every melanoma follows these rules, though. Nodular melanoma, a fast-growing subtype, often skips the typical flat, irregular shape. Instead, it appears as a firm, dome-shaped bump that can look like a blood blister. It may be red, pink, brown, black, blue-black, or even the same color as your surrounding skin. The texture ranges from smooth to crusty to rough, almost like cauliflower. These growths are usually hard to the touch, generally larger than 1 centimeter across (about the length of a staple), and they develop rapidly over several weeks. They can bleed, itch, or sting.
Because nodular melanoma doesn’t always look like a “typical” mole, dermatologists also use the “ugly duckling” sign. If one spot on your body looks noticeably different from all your other moles, that outlier deserves attention, even if it doesn’t check every ABCDE box.
Basal Cell Carcinoma: The Most Common Type
Basal cell carcinoma accounts for the majority of skin cancers. It grows slowly and rarely spreads to distant organs, but it can cause significant damage to surrounding tissue if left untreated. The most common subtype, nodular basal cell carcinoma, makes up over 60% of cases.
A typical basal cell carcinoma looks like a small, flesh-colored or pink bump with a pearly, waxy sheen. Tiny blood vessels are often visible across its surface. As it grows, the center frequently breaks down into an ulcer or depression, leaving a raised, rolled border around the edges. Some spots bleed after minor bumps or scrapes and then seem to heal, only to bleed again. Others appear as flat, pale, firm patches that look slightly translucent. Basal cell carcinomas can also contain dark areas of black-blue or brown pigment, which can make them look more alarming.
Squamous Cell Carcinoma: Scaly and Persistent
Squamous cell carcinoma is the second most common skin cancer. It tends to appear on areas that get the most sun exposure: the face, ears, neck, hands, and forearms. It can show up in several forms. A firm bump or nodule that may be pink, red, brown, or black. A flat sore topped with a scaly crust. A rough, scaly patch on the lip that may develop into an open sore. A new raised area on an old scar or wound. It can also occur inside the mouth as a sore or rough patch.
The hallmark of squamous cell carcinoma is persistence. These spots don’t heal on their own the way a normal scrape would. They may crust over, partially clear, then return. A sore that keeps coming back in the same spot is worth getting checked.
Precancerous Spots: Actinic Keratosis
Not every suspicious spot is cancer yet. Actinic keratoses are precancerous patches caused by years of sun exposure. They feel rough and sandpapery, like a patch of dry skin that won’t go away no matter how much moisturizer you use. They’re usually less than 2.5 centimeters across and can be pink, red, or brown. Some develop a hard, wart-like surface. Left untreated, a small percentage of actinic keratoses progress to squamous cell carcinoma, which is why dermatologists typically treat them early.
How Cancer Spots Look on Darker Skin
Skin cancer looks different on darker skin tones, and those differences matter because they can delay diagnosis. Basal cell carcinoma may appear as a brown, glossy black, or tan bump with a rolled border rather than the pink, pearly bump seen on lighter skin. Squamous cell carcinoma can be the same color as the surrounding skin, or pink, red, black, or brown, making it easy to overlook. Melanoma on dark skin often appears as a dark or black bump that may look waxy or shiny.
The most common melanoma subtype in people with dark skin is acral lentiginous melanoma, which occurs in places that don’t typically get much sun: the palms, soles of the feet, fingers, toes, and under the nails. It can look like a dark patch on the palm or sole, or a dark band running lengthwise under a fingernail or toenail. If a dark band under your nail begins to widen or spread, that’s a significant warning sign.
Spots That Look Suspicious but Aren’t
Seborrheic keratoses are extremely common benign growths that can look alarming. They appear as slightly raised, discolored patches that range from white to tan to dark brown or black. They have a waxy appearance and often look like they’ve been pasted or “stuck on” the skin’s surface. People frequently mistake them for unusual scabs. The key differences from melanoma: seborrheic keratoses are painless, tend to look patchy but evenly textured, and don’t follow the ABCDE pattern. Melanomas are typically asymmetrical, more than one color, larger than 6 millimeters, and change over time.
That said, telling the difference between a dark seborrheic keratosis and a melanoma can be genuinely difficult without a trained eye. When in doubt, have it examined.
What to Watch For Overall
Skin cancer doesn’t always announce itself with dramatic symptoms. Many dangerous spots are painless. In fact, 88% of Merkel cell carcinomas, a rare but aggressive skin cancer, cause no pain at all despite growing rapidly. A red or pink bump that expands quickly yet doesn’t hurt is actually more concerning than a tender one.
The most reliable approach is knowing what’s normal for your skin and noticing when something changes. The American Academy of Dermatology recommends performing regular self-exams using a body mole map so you can track your spots over time. Men over 50 face a particularly elevated risk for melanoma. Any spot that is new and growing, changing in color or shape, bleeding without clear cause, or looking different from everything else on your body warrants a closer look from a dermatologist.