Cancer doesn’t have one single look. It shows up differently depending on where it forms, and many cancers produce no visible changes at all until they’re advanced. But several types do create changes you can see or feel, and knowing what to watch for makes a real difference in catching them early. Here’s what cancer can look like on different parts of the body.
Skin Cancer: The Most Visible Type
Skin cancers are the easiest to spot because they grow right on the surface. The three main types each have a distinct appearance.
Melanoma
Melanoma is the most dangerous skin cancer, and dermatologists use five visual features (called the ABCDE criteria) to identify it. Asymmetry means one half of the spot doesn’t match the other. Border irregularity shows up as ragged, notched, or blurred edges where pigment may spread into surrounding skin. Color variation is a major red flag: instead of one uniform shade, melanomas often contain mixed shades of black, brown, and tan, sometimes with areas of white, gray, red, pink, or blue. Diameter is typically larger than 6 millimeters (about the width of a pencil eraser), though melanomas can be smaller. And evolving means the spot has changed in size, shape, or color over the past few weeks or months.
Basal Cell and Squamous Cell Carcinoma
These are far more common than melanoma and tend to look less dramatic. Early squamous cell changes often appear as reddish, scaly patches that may be crusted on the surface. Some squamous cell growths take a dome shape with a crater-like depression in the center, resembling a small volcano. Precancerous patches called actinic keratoses are usually small (under a quarter inch), rough or scaly, and pink-red or flesh-colored. They often show up on sun-exposed areas like the face, ears, and hands.
Moles That Change
Most moles are harmless, and having a lot of them doesn’t mean you have cancer. What matters is change. A mole that was flat and starts to become raised, one that develops uneven coloring, or one that grows noticeably over a few months deserves attention. The key distinction is that normal moles tend to be symmetrical, evenly colored, and stable over time. A mole that breaks any of those patterns, especially one that looks different from all your other moles, is worth having checked.
Lumps Under the Skin
Not every lump is cancer. Lipomas (fatty lumps) feel soft and doughy and move freely when you press on them. Cysts are also mobile under the skin and sometimes change in size. Cancerous lumps tend to behave differently. They’re more likely to be firm, feel fixed to deeper tissue rather than sliding around, and they don’t fluctuate in size the way cysts do. A lump that appears suddenly without explanation, feels deep, and doesn’t move easily is more concerning. That said, cancerous lumps can also be painless, so pain alone isn’t a reliable way to tell the difference.
Breast Changes You Can See
Breast cancer sometimes produces visible skin changes before you feel a lump. One of the most distinctive is dimpling, where a section of skin develops tiny indentations that make it resemble the surface of an orange peel. Your breast skin may also look rough, uneven, scaly, or reddened. Nipple changes matter too: a nipple that suddenly becomes inverted (pulled inward) when it wasn’t before, or one that produces discharge, can signal a problem. These skin-level changes happen because a tumor growing underneath pulls on the connective tissue that anchors skin to deeper breast tissue.
Changes Inside the Mouth
Oral cancers often start as patches on the tongue, gums, inner cheeks, or floor of the mouth. White patches are one warning sign, but red patches are actually more concerning. Red lesions typically have a velvety or granular texture, can be flat or slightly raised, and may bleed when scraped. Some lesions are mixed red and white. A sore anywhere in the mouth that doesn’t heal within two to three weeks is a classic early warning sign, particularly if you smoke or drink alcohol regularly.
Nail Changes Worth Noticing
Cancer can form under fingernails or toenails, and it’s easy to miss. Subungual melanoma typically appears as a dark vertical streak running from the base of the nail to the tip, looking like someone drew a line with a black or brown marker. The discoloration can be irregular with varying shades of blackish brown. These streaks usually start narrower than 3 millimeters but widen over time, often starting at the base of the nail first. The streaks can also multiply. This type of melanoma is more common on the thumb and big toe and occurs at higher rates in people with darker skin tones.
A White Glow in a Child’s Eye
One of the most striking visual signs of cancer appears in children. Retinoblastoma, a cancer of the eye, can cause the pupil to reflect white, silvery, or yellowish instead of the normal faint red glow. You might notice this in flash photography: one eye shows the typical red-eye effect while the other glows white. This happens because the tumor reflects light instead of the retina behind it. About 1 in 5 cases of this white pupil reflex in children are caused by cancer. If a white reflection appears in multiple photos and fills the entire pupil, that warrants a prompt visit to a pediatrician.
What Cancer Looks Like on a Scan
Many cancers grow deep inside the body where you can’t see or feel them. These are found through imaging like CT scans or MRIs. Radiologists look for several features that suggest a mass is cancerous rather than harmless. Malignant tumors tend to be larger, have irregular borders, and show signs of dead tissue inside them (necrosis has an 85% positive predictive value for malignancy). Cancerous masses also tend to cause swelling in the surrounding tissue and lack certain features common in benign growths, like a clear rim of fat around the edges or calcification within the mass. A benign lump is more likely to have smooth, well-defined borders and a visible capsule separating it from surrounding tissue.
General Warning Signs Across Cancer Types
Beyond what you can see on the surface, several changes can signal cancer developing anywhere in the body:
- A sore that won’t heal after several weeks, whether on skin, lips, or inside the mouth
- Unusual bleeding or discharge from any body opening
- A thickening or lump in the breast, testicles, or elsewhere
- Difficulty swallowing or persistent indigestion that’s new
- Obvious changes in a wart or mole in size, color, or shape
- A persistent cough or hoarseness lasting more than a few weeks
- Unexplained weight loss of 10 pounds or more without changes in diet or exercise
None of these guarantee cancer. Most of the time, these symptoms have ordinary explanations. But when a change is persistent, unexplained, and doesn’t resolve on its own within a few weeks, it’s the kind of thing worth bringing up at your next appointment.