Squamous cell carcinoma is the second most common type of skin cancer in the United States. It develops from the cancerous transformation of the keratinocyte cells from the top-most layer of the skin (epidermis). A squamous cell carcinoma that is confined to the epidermis is referred to as a squamous cell carcinoma in situ (SCCis). This is considered an early stage for squamous cell carcinoma. When the cancerous cells break through the epidermis and grow more deeply, it is referred to as an invasive squamous cell carcinoma. A recent staging system has been developed for squamous cell carcinomas and takes into account the size, depth, location, nerve involvement, spread, and other tumor characteristics. As with basal cell carcinoma, squamous cell carcinomas can also cause local tissue destruction. However, depending on its stage and a variety of other factors, squamous cell carcinomas are thought to have a higher chance of life-threatening spread to the rest of the body than basal cell carcinomas.
Squamous cell carcinoma can be found anywhere on the skin, but is most common on sun-exposed areas. Ultraviolet radiation exposure from sunlight and tanning beds are common risk factors for developing squamous cell carcinomas. Other causes of squamous cell carcinomas include contact with certain toxic chemicals, a suppressed immune system, and infection with certain subtypes of the Human Papilloma Virus (HPV).
The diagnosis of a squamous cell carcinoma will require a biopsy. Many treatment options are available, including but not limited to topical medications, Mohs micrographic surgery, and standard surgical excisions. The most appropriate treatment option will be determined by your dermatologist based on a number of factors including the stage of the squamous cell carcinoma, its location, and other personal medical conditions.