These are the two most common skin cancers, and both are usually curable when they are found early. Neither one is melanoma, which is the rarer and more dangerous type.
Basal cell carcinoma is the most common and the least aggressive. It grows slowly and almost never spreads elsewhere in the body. Left alone for years, though, it keeps growing outward and downward and can do real local damage.
Squamous cell carcinoma grows faster and can spread. Spread is still uncommon, but it is possible, which is why this one is treated with more urgency.
If you are reading this because of a spot you have, the useful summary is: anything that bleeds, scabs, heals, and comes back in the same place needs to be looked at. That pattern is the most reliable warning sign either one gives.
About 8 in 10 skin cancers that are not melanoma.
About 2 in 10.
A small raised bump with a glossy or waxy surface, sometimes with tiny visible blood vessels running across it. Can also look like a pale flat scar, or a sore that will not heal.
A firm red bump, a scaly patch, or a sore with a raised, hard edge. Often has a thick crust that keeps coming back.
May bleed easily from minor contact, then scab, then bleed again.
More likely to be sore or painful to touch, and more likely to feel firm and fixed.
Face, nose, ears, scalp, neck, shoulders. The nose is the single most common spot.
Face, ears, lips, backs of hands, forearms. Also on scars, chronic wounds, and inside the mouth or on the genitals.
Spread beyond the original site is very rare. The damage it does is local.
Higher risk on the lip and ear, in large or deep tumours, and in people whose immune systems are suppressed.
A small rough, scaly, sandpapery patch on sun-damaged skin. A small fraction of these turn into SCC, which is why they get treated.
Most are removed with a simple excision under local anaesthetic. On the face, and anywhere the edges are unclear, Mohs surgery is common — the surgeon removes thin layers and checks each one under the microscope until no cancer remains, which spares the most healthy skin.
Same approach, with a wider margin. For higher-risk tumours a doctor may also examine nearby lymph nodes or order imaging.
Most skin cancers are not found because someone recognised the medical description. They are found because of one of these:
Any of those is worth an appointment. None of them means you have cancer — most turn out to be something harmless — but they are exactly the things worth checking.
Sunscreen every day on your face, ears, neck and the backs of your hands, whatever the weather. A hat with a real brim beats sunscreen on the scalp and ears, which are the two places people always miss. No tanning beds.
And if you have had one skin cancer already, keep the follow-up appointments. The strongest predictor of a future skin cancer is having had one.
Do not wait to see whether it settles. These do not go away on their own, and every one of them is easier to treat small.