A physician should be consulted if a person experiences skin changes, such as a new lump or an abnormally shaped mole. In general, skin lesions that remain more than two months are more likely to be skin cancer than those that go away in that time. If cancer is suspected, the patient will need to undergo a biopsy; a dermatologist takes a tissue sample, and a dermatopathologist examines the tissue under a microscope.
If a cancer covers an extensive area of skin, or is suspected of invading underlying tissues or structures, CT scan, MRI and other tests may be needed to determine how far the cancer has spread.