More than 100,000 new squamous cell carcinomas appear each year. Most arise from sun-damaged skin, often in precancerous lesions called actinic keratoses. Men are more commonly affected than women, and increasing age increases the risk of developing a squamous cell carcinoma.
Tumors commonly arise in areas of sun damage, and are common on the head, neck, and hands.
Squamous cell carcinomas usually grow slowly, beginning as in situ tumors which may progress to an invasive or metastatic tumor. Her past medical history was remarkable for cadaveric renal transplantation 4 years earlier. She had had no episodes of rejection and was being maintained on chronic immunosuppressive therapy. She complained about the recent appearance of several scaly, erythematous plaques on her upper extremity. Physical examination revealed several well-demarcated erythematous papules and plaques on both upper extremities.