The type of skin cancer you develop depends on the type of cell it started in. For example, if the cancer begins in the round basal cells below the skin’s surface, it’s known as basal cell skin cancer. The three most common types of skin cancer are, in order from most to least: basal cell carcinoma, squamous cell carcinoma, and melanoma. While these make up most of the cases, there are other, rarer forms of cancer that can also affect the skin. No matter what kind, skin cancer should be diagnosed and treated quickly to avoid complications. (1,2) RELATED: Types of Skin Cancer: Do You Know How to Spot Them? Rates of basal cell carcinoma have been increasing. Experts believe this is due to more sun exposure, longer lives, and better skin cancer detection methods. (4) This type of cancer begins in the skin’s basal cells, which are found in the outermost layer, the epidermis. Basal cell carcinomas usually develop on areas that are exposed to the sun, like the face, head, and neck. (5) They may look like: (2,6)

A flesh-colored, round growthA pearl-like bumpA pinkish patch of skinA bleeding or scabbing sore that heals and then comes back

Basal cell carcinomas typically grow slowly and don’t spread to other areas of the body. But, if these cancers aren’t treated, they can expand deeper and penetrate into nerves and bones. (2) Though it’s rare, basal cell carcinoma can be life-threatening. Experts believe that about 2,000 people in the United States die each year from basal cell carcinoma or squamous cell carcinoma. (4) Some risk factors that increase your chances of having a basal cell carcinoma include: (7,8)

Being exposed to the sun or indoor tanningHaving a history of skin cancerBeing over age 50Having fair skin with light eyes and blond or red hairBeing maleHaving chronic infections, skin inflammation, or a weakened immune systemBeing exposed to industrial compounds, radiation, coal tar, or arsenicHaving an inherited disorder, such as nevoid basal cell carcinoma syndrome or xeroderma pigmentosum

People who develop a basal cell carcinoma have a higher risk of having another one. This usually happens within three to five years of the first one. (3,9) RELATED: New AAD Guidelines Address Best Practices for Preventing and Treating Basal Cell and Squamous Cell Skin Cancer This type of cancer starts in flat cells in the outer part of the epidermis. It commonly crops up on sun-exposed areas, such as the face, ears, neck, lips, and hands. It can also develop on scars or chronic sores. Squamous cell carcinomas may develop from precancerous skin spots, known as actinic keratosis (AK). These cancers might look like: (2,6)

A firm, red bumpA flat lesion with a scaly, crusted surfaceA sore that heals and then reopens

People with lighter skin are more at risk for developing squamous cell carcinoma, but the skin cancer can also affect those with darker skin. (2) Other risk factors include: (10)

Having light eyes, blond or red hair, or frecklesBeing exposed to the sun or tanning bedsHaving a history of skin cancerHaving a history of sunburnsHaving a weakened immune systemHaving the genetic disorder xeroderma pigmentosum

RELATED: 10 Things You May (or May Not) Know Cause Skin Cancer This cancer starts in the melanocytes — cells in the epidermis that make pigment. About 100,000 new melanomas are diagnosed each year. (11) Risk factors for melanoma include: (12)

Having fair skin, light eyes, freckles, or red or blond hairHaving a history of blistering sunburnsBeing exposed to sunlight or tanning bedsLiving closer to the equator or at a higher elevationHaving a family history of melanomaHaving many moles or unusual-looking molesHaving a weakened immune system

Melanoma can develop within a mole that you already have, or it can pop up as a new dark spot on your skin. (2) This cancer can form anywhere on your body, but it most often affects areas that have had sun exposure, such as the back, legs, arms, and face. Melanomas can also develop on the soles of your feet, palms of your hands, or fingernail beds. (12) Signs to watch out for include: (12)

A mole that changes in color, size, or how it feelsA mole that bleedsA large brownish spot with darker specksA lesion with irregular borders or parts that appear red, white, blue, pink, or bluish-blackA mole that’s asymmetricalA painful lesion that burns or itchesDark spots on the soles of your feet, palms, fingertips, toes, or the lining of your mouth, nose, vagina, or anusA very large mole

RELATED: The Difference Between Chemical and Mineral Sunscreen Though it’s an uncommon skin cancer, cases of Merkel cell carcinoma have increased rapidly in the past couple of decades. (13) This type of cancer starts when certain cells in the skin — Merkel cells — start to grow out of control. Merkel cell carcinomas typically grow quickly and can be difficult to treat if they spread. (14) They can start anywhere on the body, but Merkel cell carcinomas commonly affect areas exposed to the sun, such as the face, neck, and arms. They may look like pink, red, or purple lumps that are firm when you touch them. Sometimes, they can open up as ulcers or sores. (6) Risk factors include: (15)

Being exposed to excessive amounts of ultraviolet light via the sun or tanning bedsHaving a weakened immune systemHaving a history of other skin cancersBeing older than 50Having light skin

RELATED: Beating the Odds Against Merkel Cell Carcinoma

Kaposi Sarcoma

Kaposi sarcoma forms in the skin’s blood vessels and is caused by human herpesvirus 8. This type of skin cancer mainly affects people with weakened immune systems, such as those with acquired immunodeficiency syndrome (AIDS) or individuals who take immune-suppressing medicines. Other forms of Kaposi sarcoma commonly affect young men living in Africa or older men with Mediterranean or Jewish heritage. Kaposi sarcoma appears as red or purple patches on the skin. Lesions might also form in the lining of the mouth, lungs, anus, or digestive tract. (1,6,16)

Actinic Keratosis

Actinic keratosis (AK), also known as solar keratosis, is a precancerous lesion that can develop into squamous cell carcinoma. The condition is caused by excessive exposure to UV radiation from the sun or indoor tanning. AK may look like a small, dry, scaly, or crusty patch of skin. These spots can appear red, tan, white, pink, flesh-toned, or a mix of colors. About 58 million people in the United States have one or more AKs. Only around 5 to 10 percent of AKs turn into skin cancer, but most squamous cell carcinomas start off as AKs. (17)

Lymphoma of the Skin

Cutaneous lymphoma is a type of non-Hodgkin lymphoma that affects the skin. It begins in white blood cells called T cells, which normally help your body fight germs. This type of cancer can cause a rash, raised or scaly patches on the skin, or skin tumors. There are several different types of cutaneous T-cell lymphomas, and some are more aggressive than others. (1,18)

Keratoacanthoma

Keratoacanthomas are tumors that develop slowly and may even go away on their own without any treatment. If they continue to grow, they’re treated like a form of squamous cell carcinoma. These tumors are usually dome-shaped and found on areas of the skin that are exposed to the sun. (1,3)

Sebaceous Gland Carcinoma

Sebaceous gland carcinomas are uncommon but aggressive cancers that start in the oil glands of the skin. They usually appear as hard nodules that are painless. These cancers can develop anywhere but most often are found on the eyelid. (6)

Dermatofibrosarcoma Protuberans (DFSP)

Dermatofibrosarcoma protuberans (DFSP) is a rare type of skin cancer that begins in the middle layer of the skin. It typically grows slowly and doesn’t spread to other parts of the body. The first sign of DFSP is usually a small bump that looks like a deep-seated pimple or rough patch of skin. It can also look like a scar; in children, it may resemble a birthmark. (19)