In situ SCC. This is the mildest type. The tumour is confined to the outer layer of the skin (epidermis). This type of cancer is also sometimes called Bowen’s Disease. Patients often grow many of these mild skin cancers. Surgery is not always required. Some can be treated with creams such a 5 Fluorouracil or by curettage. Almost all these cancers are cured with treatment. In situ SCCs often appear as a thick scaly red rash. The lesion slowly expands in size.
Well differentiated SCC. This is the commonest type. The SCC has grown into the deeper layers of the skin (dermis). Now there is a small risk that the cancer has spread elsewhere in the body. Treatment of these cancers is almost always surgical with a healthy margin of normal skin removed surrounding the cancer. Creams are not used. Follow up visits involve checking for other skin cancers as well as checking for the risk of tumour spread. Well differentiated SCCs often appear as very thick crusty lesions on the skin. Often the top falls off. Sometimes patients think they may have gone away. But invariably the scaly crusty top returns.
Keratoacanthoma. This is a particular type of SCC that grows very quickly yet is not very dangerous. Often they appear and grow large in 6 to 10 weeks. They can look like a mini volcano. The foothills of the volcano can look like stretched skin. The centre of the crater is often full of loose tissue. In most cases treatment is surgical excision. Usually the only way one can be sure a lesion is a keratoacanthoma and not a more serious SCC is by the pathologist making the diagnosis under the microscope following excision. These cancers almost never spread elsewhere in the body.
Aggressive SCCs. There are several types of SCC in this category. They include poorly differentiated and spindle cell types. These SCCs have a greater tendency to spread elsewhere in the body. Surgery with a wide margin of apparently normal skin is required. Sometimes scans of the lymph nodes or other organs are needed to check for any evidence of tumour spread. These SCCs have a variable appearance of the skin. Some are soft and others are hard. Some bleed on and off. They usually grow quickly and may double in size over months.
Actinic keratoses. These are at the opposite end of the spectrum to aggressive SCCs. These are merely sunspots. They are very common. The skin is severely sun damaged and the cells in the outer epidermis layer are now quite abnormal. There is controversy as to whether we should even call these lesions “cancers” in this early phase. Treatment is not surgical. We treat these lesions with creams or cryotherapy. For some thicker lesions curettage is used. However, sometimes the only way to distinguish thick actinic keratoses from well differentiated SCCs is to biopsy or excise them.
Dr. Anthony Dixon