is a major type of cancer that arises from the outer epidermal layer of the skin and mucous membranes and occurs most commonly on areas exposed to the sun. If untreated, squamous cell carcinoma may penetrate and destroy underlying tissue. In a small percentage of cases, this tumor can spread (metastasize) to distant organs and may be fatal.
Chronic sun exposure is the leading cause of squamous cell carcinoma, especially in people with fair skin, light hair and blue, green or grey eyes. Other factors that may contribute to the development of this cancer include burns, scars, exposure to radiation or chemicals, chronic inflammatory conditions and immunosuppression.
Although more likely to develop in fair-skinned individuals, squamous cell carcinoma may occur in dark-skinned people, especially at sites of preexisting inflammatory conditions or burns. Signs that may indicate the presence of squamous cell carcinoma include scaly red patches, elevated growth with a central depression, wart-like growths, nodules and open sores. All of these types of lesions may develop a crusted surface or bleed.