Your skin is made up of different cells that play distinct roles from each other. The round basal cells just below the surface help replace dead and flaky squamous cells on the surface of the skin. Merkel cells enable the sense to touch, and melanocytes help tan the skin. Skin cancers often begin in the cells of the superficial layers of the skin called the epidermis.

While most skin cancers rarely spread to other parts of the body, specific skin cancer types like malignant melanoma can metastasize and become life-threatening.

The out-of-control growth of abnormal cells in the epidermis is often the result of DNA damages. The mutations can cause the skin cells to multiply rapidly to form tumors. The main causes of skin cancers are harmful ultraviolet rays of the sun and using UV tanning machines.

The different types of skin cancer are divided into four main types and they are:

Basal cell carcinoma
This cancer develops within the base cell layers of the skin below the epidermis. It’s that area of the skin that receives maximum sun exposure. It’s a very slow-growing cancer, and it’s even for this cancer to metastasize or spread. However, leaving it untreated for a long time can spread elsewhere, including nearby lymph nodes. This cancer can recur in the same location where it had developed earlier. In fact, developing a new basal cell cancer is very likely in individuals who had developed it earlier. It can also develop in new areas of the body. The most common areas affected by this cancer are the face, neck, ears, scalp, shoulders, and back.

Squamous cell carcinoma
This type of skin cancer develops in the flat squamous cells that form the largest part of the outermost layer of your skin, the epidermis. It’s also very common in areas that are constantly exposed to the sun. This type of skin cancer can invade the fatty tissues under the skin and spread further.

Melanoma
This is the most serious type of skin cancer that develops in the cells, melanocytes. While it’s less common than basal cell carcinoma and squamous cell carcinoma, this condition can be dangerous due to its ability to spread rapidly to other organs. Melanocytes are the skin cells that produce melanin pigment that gives your skin its color. This skin cancer often triggers due to recurrent sun exposure that causes sunburn. Frequent use of tanning beds also significantly increases the risk of developing melanoma.

Merkel cell carcinoma
This rare and very aggressive type of skin cancer affects the Merkel cells that have nerve endings. These cells give you the sense of touch, and this condition predominantly affects the face or the scalp due to excessive sun exposure. It’s a dangerous type of skin cancer that can metastasize and spread to the bones, brain, lungs, and liver. These tumors are painless, firm lesions that also appear as nodules on the sun-exposed areas.