What skin cancer looks like and when to see a doctor

Skin cancer usually shows up as a new spot on your skin, or a change to a spot you've had for years. The most common sign is a mark that looks different from your other moles or freckles—either in color, size, shape, or the way it feels. Not every unusual spot is cancer, but any mark that changes or doesn't match the pattern of your other skin should be checked by a dermatologist or your primary care doctor.

The key is noticing what's new or different on your own skin. Most people have dozens of moles and spots; skin cancer usually announces itself by standing out from the rest. If you've never had a particular spot before, or if one you've ignored for years suddenly starts changing, that's the moment to schedule an appointment.

Key Takeaways

  • The ABCDE rule—Asymmetry, Border irregularity, Color variation, Diameter larger than a pencil eraser, and Evolving (changing)—helps you spot melanoma, the most dangerous form of skin cancer.
  • Basal cell carcinoma often appears as a shiny bump or a sore that doesn't heal, usually on the face, ears, or neck.
  • Squamous cell carcinoma typically shows up as a scaly, crusty, or bleeding patch, often on sun-exposed areas.
  • Any spot that itches, bleeds, oozes, or changes in size, shape, or color within weeks or months warrants a doctor's visit.
  • A dermatologist can usually diagnose skin cancer with a visual exam, though a biopsy (removing a small sample) confirms the diagnosis.

The ABCDE rule for melanoma

Melanoma is the most serious form of skin cancer, and doctors teach the ABCDE rule to help people spot it early. Each letter stands for a warning sign:

Asymmetry means one half of the spot doesn't match the other half. Draw an imaginary line through the middle; if the two sides look different, that's a red flag. Border refers to edges that are jagged, notched, or blurry rather than clean and even. Color variation means the spot contains more than one shade—browns, blacks, tans, reds, or even white or blue mixed together. Diameter larger than a pencil eraser (about 6 millimeters) is concerning, though melanoma can be smaller. Evolving means the spot is changing—getting bigger, darker, itching, or bleeding.

A spot doesn't need to have all five signs to be melanoma, but any one of them is worth showing to a doctor. The ABCDE rule catches most melanomas, but it's not perfect; some early melanomas are small and uniform in color, so any new or changing spot deserves attention.

Basal cell carcinoma: the most common type

Basal cell carcinoma accounts for about 80 percent of all skin cancers and grows slowly. It usually appears on the face, ears, scalp, or neck—areas that get sun exposure—but can show up anywhere.

Common signs include a shiny, waxy bump that may be pink, red, or skin-colored; a sore that bleeds, oozes, or crusts over but doesn't heal within a few weeks; or a flat, scaly patch that may be red or brown. Some basal cell carcinomas look like a small scar. The spot may itch or bleed if you pick at it, but often it causes no pain or other symptoms, which is why people sometimes ignore it for months.

Because basal cell carcinoma grows slowly and rarely spreads to other parts of the body, catching it early is less urgent than with melanoma—but early treatment still prevents scarring and disfigurement, especially on the face.

Squamous cell carcinoma: scaly and crusty

Squamous cell carcinoma is the second most common skin cancer. It typically appears as a firm, scaly, or crusty bump on sun-exposed skin like the face, ears, lips, hands, or forearms. The spot may be red, pink, or skin-colored.

You might notice it bleeds easily, doesn't heal, or keeps coming back after you think it's gone. Some squamous cell carcinomas look like a wart or a rough patch of skin. Unlike basal cell carcinoma, squamous cell carcinoma can spread to lymph nodes or other parts of the body if left untreated, though this is still uncommon when caught early.

Any persistent sore or scaly patch on sun-exposed skin that lasts more than a few weeks should be checked. Squamous cell carcinoma grows faster than basal cell carcinoma, so earlier diagnosis matters more.

Changes that warrant a doctor visit

You don't need to memorize every warning sign. The simplest rule is this: if a spot on your skin is new, or if a spot you've had for years suddenly starts changing, make an appointment. Changes to watch for include growth in size, darkening or lightening in color, bleeding or oozing without injury, itching or tenderness, or a change in texture (becoming scaly, bumpy, or crusty).

Pay special attention to spots on your face, ears, scalp, hands, feet, or genitals—areas that either get heavy sun exposure or are often overlooked. A spot that's been stable for years and then changes is sometimes more concerning than a new spot, because it suggests something has shifted in that area of skin.

If you're unsure whether a spot needs checking, the safest choice is to show it to a doctor. A dermatologist can evaluate dozens of spots in one visit and will tell you which ones, if any, need monitoring or removal.

What happens at a skin cancer check

A dermatologist or primary care doctor usually diagnoses skin cancer by looking at the spot with the naked eye or with a magnifying tool called a dermatoscope. In many cases, a visual exam is enough to identify basal cell or squamous cell carcinoma.

If the doctor suspects melanoma or is uncertain about a spot, they will perform a biopsy—removing a small sample of skin under local anesthesia and sending it to a lab for examination under a microscope. A biopsy is the only way to confirm skin cancer and determine exactly what type it is. The procedure takes a few minutes, leaves a small mark, and results usually come back within one to two weeks.

If skin cancer is confirmed, your doctor will discuss treatment options, which vary depending on the type, size, and depth of the cancer. Early-stage skin cancers are almost always curable with outpatient treatment.

Frequently Asked Questions

Can I tell if a spot is skin cancer just by looking at it?

No. While the ABCDE rule and other signs raise suspicion, only a doctor can diagnose skin cancer. Many benign spots look concerning, and some early skin cancers look harmless. If you're unsure, have it checked rather than watching and waiting.

Does skin cancer always itch or hurt?

No. Many skin cancers cause no symptoms at all. Some itch or bleed, but plenty don't. The absence of pain or itching doesn't mean a spot is safe—appearance and change are what matter most.

What if I have a lot of moles—how do I know which ones to worry about?

Focus on spots that are new or changing, or that look noticeably different from your other moles. If you have many moles, a dermatologist can photograph them and track changes over time, which is especially useful if you have a family history of melanoma.

How quickly does skin cancer grow?

It varies. Basal cell carcinoma grows slowly over months or years. Squamous cell carcinoma grows faster, over weeks to months. Melanoma can grow quickly, which is why any changing spot should be checked promptly rather than monitored at home.

If I had a spot removed years ago, can skin cancer come back in the same place?

Recurrence at the exact same spot is rare if the entire lesion was removed. However, people who've had one skin cancer are at higher risk for developing another one elsewhere on their body, so ongoing skin checks are important.