What causes it?

Basal cells are normal skin cells. They may develop cancerous changes, causing a lump or bump that is painless. A new skin growth that ulcerates, bleeds easily, or does not heal well may indicate development of basal cell skin cancer. This type of skin cancer has a high cure rate, but neglect can allow the cancer to enlarge, causing possible disability or, in rare cases, death.

More than 90% of basal cell carcinomas occur on areas of skin that are regularly exposed to sunlight or other ultraviolet radiation. They may also occur on the scalp. The onset most commonly occurs after age 40.