If you’ve had a basal cell carcinoma you may be more likely to develop a squamous cell carcinoma, as is anyone with an inherited, highly UV-sensitive condition such as xeroderma pigmentosum. Chronic infections, skin inflammation, HIV and other immune deficiency diseases, chemotherapy, anti-rejection drugs used in organ transplantation, and excessive sun exposure can all lead to a risk of squamous cell carcinoma.
Occasionally, squamous cell carcinomas arise spontaneously on what appears to be normal, healthy skin. Some researchers believe the tendency to develop these cancers can be inherited.
SCCs may occur on all areas of the body including the mucous membranes and genitals, but are most common in areas frequently exposed to the sun: the ear, lower lip, face, bald scalp, neck, hands, arms and legs. Often the skin in these areas also reveals telltale signs of sun damage, such as wrinkling, changes in pigmentation, and loss of elasticity, especially as the patient gets older.