Often appears as a nodular lesion of the "wart", "lozenge" or "horn" type. These lesions are hard, reddish in color, opaque, surrounded by slight inflammation and have faster growth. They are commonly found on sun-exposed areas of the body, such as the back of the hands, the lower lip, the lower neckline, the ears, the forehead, and the scalp in bald patients.
The cancerous cells are sometimes confined for a while to the epidermis (the outermost layer of the skin). They have a slower growth rate without invasion. These spinocellular carcinomas in situ go by the name of Bowen's disease or erythroplasia of Queyrat (when they appear on the glans penis).
Other flat lesions, reddish in color, with scaling and spicules, and found on the same areas of the body of people with fair skin, may be the forerunners of this type of cancer. Regarded by some authors as true superficial spinocellular carcinomas, they are known as actinic or solar keratoses (AK). They have a very high incidence rate and are likely to reappear. Although they are benign, their importance as lesions signalling the appearance of spinocellular carcinomas makes them the target of tests for multiple treatments aimed at tackling skin cancer at its inception: before it appears.

Actinic keratoseson the back of the hands of a patient with fair skin (illustration above). Detaii of the same lesions.Scaling with spike-like spicules can be seen, with surrounding inflammation (illustration below).