What Do I Need to Know About the Different Types of Skin Cancer?

Basal Cell Carcinoma

Starting in the basal cells in the lower epidermis (outer layer of the skin), basal cell carcinoma is the most common type of skin cancer. In fact, it accounts for about 80% of all cases of skin cancer, according to the American Cancer Society. This type of skin cancer is more likely to occur in people with fair skin, but anyone can develop basal cell carcinoma. The most significant risk factor is frequent exposure to the sun or tanning beds.

Basal cell carcinoma is very treatable and has a good prognosis, but early diagnosis and treatment are important to prevent it from spreading to surrounding tissues. Common characteristics of basal cell carcinoma include raised patches that may itch, pearly looking bumps, pale patches that resemble a scar, and open sores that won’t heal. In most cases, it’s found on the face, neck, arms and other areas frequently exposed to the sun, but it could also appear on the torso and legs.

Squamous Cell Carcinoma

Squamous cell carcinoma is the second most common type of skin cancer, accounting for about 20% of cases. Unlike basal cell carcinoma, which typically affects the outer layers of the skin, squamous cell carcinoma can grow in deeper layers of the skin. This type of skin cancer also occurs most often on parts of the body that are frequently exposed to the sun, such as the ears, face, neck and arms.

A more troublesome form of squamous cell carcinoma that is linked to the human papillomavirus (HPV) affects the mucous membranes or the genital area. Left untreated, squamous cell carcinoma can spread to other parts of the body and cause severe damage and disfigurement due to deeper penetration into the skin. Common characteristics include raised lumps, scaly red patches, growths that resemble warts, and sores that heal but then re-open.

Melanoma

Accounting for only about 1% of all skin cancer cases, melanoma is not a common type of skin cancer, but it’s definitely the deadliest form because of its fast growth and ability to spread to other organs. It starts in the melanocytes, usually on the back, chest or legs, but it can develop anywhere on the body. The face, neck, hands, feet and nail beds can also be sites for melanoma. This type of skin cancer typically starts in an existing mole or first appears as a new dark spot or mole on the skin, which is why moles should always be monitored carefully.

Doctors use the ABCDE warning sign model to help patients identify potential problem moles: Asymmetry, Border, Color, Diameter and Evolving. An asymmetrical mole is misshapen with sides that don’t match. A problem mole doesn’t have a clearly defined border and could have jagged, uneven edges with pigment that spreads into the surrounding skin. Moles should only be a single color. If a mole isn’t the same color throughout and includes shades of tan, brown, black and even red or white, it could signal a problem. If the mole is greater than 6 mm in diameter or suddenly increases in size, it should be checked. Evolving refers to changes; if the mole has changed in appearance in the past weeks or months, it could be cause for concern.

Rare Skin Cancers

Several other types of skin cancer exist but are extremely rare, accounting for less than 1% of all skin cancers when grouped together. Merkel cell carcinoma affects neuroendocrine (Merkel) cells near the nerve endings in the epidermis. Although it’s rare, this type of skin cancer is dangerous due to its ability to spread to other organs and the difficulty of treating it after it spreads.

Kaposi sarcoma is a rare form of cancer that often appears as red, purple or brown tumors on the skin or in the mouth. The cells that form the cancer originate in the lining of the lymph nodes or blood vessels. If the tumors spread to critical organs like the lungs or liver, it could be life threatening.

Skin lymphoma is a type of non-Hodgkin’s lymphoma. To be a skin lymphoma, the cancer must start in the lymphocytes in the skin and not travel to the skin from other organs. Survival rates for skin lymphomas vary, depending on the exact type and the response to treatment.  

Squamous Cell Precancers

Squamous cell precancers serve as warning signs for skin conditions that could potentially turn into skin cancer. Nearly all of them are linked to UV sun exposure, and it's important to monitor them closely to ensure an early diagnosis and treatment if the precancers become malignant.

Actinic keratoses look like dry, scaly patches that develop on older adults who have had decades of sun exposure. Keratoacanthoma tumors are dome-shaped and grow quickly at first but then stabilize. They closely resemble squamous cell carcinoma. Bowen disease looks similar to eczema or psoriasis, forming red-brown, scaly patches on the surface of the skin.

Resource Links:

https://www.cancer.org/cancer/skin-cancer.html

https://www.cancer.org/cancer/basal-and-squamous-cell-skin-cancer/about/what-is-basal-and-squamous-cell.html

https://www.cancer.org/cancer/basal-and-squamous-cell-skin-cancer/detection-diagnosis-staging/signs-and-symptoms.html

https://www.cancer.org/cancer/melanoma-skin-cancer/about/what-is-melanoma.html

https://www.cancer.org/cancer/melanoma-skin-cancer/about/key-statistics.html

https://www.cancer.org/cancer/merkel-cell-skin-cancer/about/what-is-merkel-cell-carcinoma.html

https://www.cancer.org/cancer/kaposi-sarcoma/about/what-is-kaposi-sarcoma.html

https://www.cancer.org/cancer/skin-lymphoma/about/what-is-lymphoma-of-the-skin.html