*Risk factor for developing squamous cell carcinoma:

Frequent exposure to sunlight, tanning beds, and/or sunlamps over many years

Pale white skin and tendency to burn or freckle rather than tan

Family history of squamous cell carcinoma

Overexposure or long-term exposure to X-rays

Chronic skin ulcers

Actinic keratoses

Long-term treatment with immunosuppressive drugs, such as those used to prevent organ rejection

Weakened immune system; conditions that weaken the immune system include lymphoma and human immunodeficiency virus (HIV)

Tobacco use

History of exposure to arsenic, coal, industrial tar, or paraffin

Received (PUVA) therapy for treatment of psoriasis

Xeroderma pigmentosum, a rare inherited condition that makes one less able to repair damage caused by sunlight

*Risk factors for basal cell carcinoma:

Chronic sun exposure mainly to UVB radiation but also UVA

A history of repeated sunburns or childhood exposure to the sun

A suppressed immune system

HIV disease

Ionizing radiation used for acne in the 1940's

Fair skin and the propensity to freckle or burn rather than tan

Exposure to arsenic

A condition called granuloma inguinale

Scarred or previously damaged skin, especially radiation damage

Rare genetic diseases such as xeroderma pigmentosa, nevoid basal cell carcinoma syndrome, and albinism