The most common types are as follows:

• Basal Cell Carcinoma (also known as epithelial carcinoma). These carcinomas are more localized and develop more slowly. As regards prognosis, they can be cured if diagnosed early. Basal cell carcinoma is by far the most common type, but it is also less likely to spread. Its risk derives mainly from localized invasion and destruction of tissue that leads to its growth.
• Spinocellular carcinoma (squamous cell carcinoma). Though less common, this type is more aggressive and is liable to develop quickly. It may affect regional ganglia and thereafter become generalized.
• Melanoma (known as malignant mole) is the most serious type and is liable to spread easily. Prognosis depends on early detection.