Skin cancers originate in the skin due to abnormal cell growth. Skin cancer is the most common form of cancer and can be cured effectively if diagnosed and treated early.
Skin cancers originate in the skin due to abnormal cell growth. Skin cancer is the most common form of cancer and can be cured effectively if diagnosed and treated early.

Skin cancers originate in the skin due to abnormal cell growth. Skin cancer is the most common form of cancer and can be cured effectively if diagnosed and treated early. Most often, skin cancer develops in parts of the body exposed to the sun, such as the scalp, face, lips, ears, neck, chest, arms, hands, and legs (in women). Sometimes, it forms in places that are not exposed to the sun, such as palms, under fingernails or toenails, and genital areas.

Skin cancer is caused by the damage and subsequent changes to the deoxyribonucleic acid (DNA) that trigger mutations. DNA mutations are induced by the sun’s harmful ultraviolet (UV) rays in the cells of the epidermis (outer layer of skin). These mutations cause the skin cells to grow rapidly and form malignant tumors.

What are the risk factors for skin cancer?

Factors that increase the risk of developing skin cancer include:

  • Excessive exposure to ultraviolet rays from the sun, tanning lamps, or other sources
  • History of sunburn
  • Living in tropical or high-altitude regions
  • Family history of skin cancer
  • History of any skin cancer
  • Age older than 50 years
  • Pale or freckled skin
  • Natural blond or red hair
  • Blue or green eyes
  • Male gender
  • Chronic infections and skin inflammation from scars and other conditions
  • Sun-sensitive conditions, including xeroderma pigmentosum
  • Extensive burns
  • Precancerous skin growths, including actinic keratosis
  • Human papillomavirus (HPV) infection
  • Weakened immune system due to illness (human immunodeficiency virus infection and acquired immune deficiency syndrome or HIV/AIDS)
  • Taking certain immunosuppressive medications
  • Radiation exposure
  • Exposure to chemicals, such as arsenic, pitch, or creosote
  • Multiple, large, or irregular moles


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What are the signs and symptoms of skin cancer?

The common symptoms of skin cancer include:

  • Unusual changes in the skin
  • Skin lesions that don’t go away, such as new mole, unusual growth, sore, scaly patch, or dark spot
  • Lesions with ragged edges
  • Asymmetrical lesions
  • Lesions with unusual colors, such as white, pink, black, blue, or red
  • Large lesions
  • Evolving lesions or moles that change their size, color, or shape

What are the types of skin cancer?

Basal cell carcinomas arise from the basal cells in the epidermis (outer layer of skin). It appears as a painless raised area on the skin that may be shiny with small blood vessels running over it or as a raised area with an ulcer. This is the most common type of skin cancer and is usually treatable because it doesn’t spread far.

Squamous cell carcinoma arises from the squamous cells in the epidermis. It usually appears as a hard lump with a scaly top but may also form an ulcer. They are more likely to metastasize if they are not detected and treated early.

Melanoma is cancer that develops from melanocytes, the skin cells that produce melanin pigment. Melanomas resemble moles and sometimes arise from them. Melanoma is less common than other types of skin cancer but is more likely to grow and spread.

Merkel cell carcinoma is rare, aggressive skin cancer. The tumors appear as firm, painless lesions or nodules beneath the skin and in hair follicles on sun-exposed areas. They are usually associated with Merkel cell polyomavirus and have high risks of recurring and metastasizing.

Skin lymphomas or cutaneous lymphomas arise in cells of the immune system in the skin.

This is a rare skin cancer that develops in lymph nodes or blood vessels in the skin. They appear as red, brown, or purple patches or tumor on the skin or mucous membranes. It is seen in people with severely compromised immune systems, such as AIDS or inborn defects in white blood cells.

Sebaceous gland carcinoma is an uncommon, aggressive cancer that develops from the sebaceous (oil) glands in the skin. They usually appear as hard, painless nodules.

What are the stages of skin cancer?

Skin cancer is staged based on the extent of cancer spread:

  • Stage 0: Cancer cells have not spread beyond the epidermis.
  • Stage I: Cancer spreads to the next layer of skin, the dermis.
  • Stage II: Tumor is larger than 2 cm.
  • Stage III: Cancer has spread to nearby tissue, lymph node, or bone and is larger than 3 cm.
  • Stage IV: Cancer has metastasized and spread beyond the primary tumor site to lymph nodes, muscles, nerves, bone, or other organs of the body.

How is skin cancer treated?

Treatment options for skin cancer depend on the size, location, type, and stage of cancer:

  • CryotherapyThe tumor is frozen with liquid nitrogen, and then, the dead tissues are removed when the tumor thaws.
  • Curettage and electrodessication: Layers of cancer cells are scraped away using a curette (spoon-like instrument), and any remaining cancer cells are destroyed with an electric needle.
  • Excisional surgery: Cancerous tissue and surrounding healthy skin are removed.
  • Mohs surgeryTumor is removed layer by layer until no abnormal cells remain without removing excessive healthy skin.
  • Chemotherapy: Specific medications are used to kill cancer cells.
  • Radiation therapy: High-powered energy beams are used to kill cancer cells.
  • Photodynamic therapyCancer cells are destroyed using a combination of laser light and medications.
  • Immunotherapy/Biological therapyThis treatment encourages the body’s immune system to destroy cancer cells.


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Can skin cancer be prevented?

Most skin cancers can be prevented by:

  • Avoiding direct sun exposure
  • Avoiding tanning beds and sun lamps
  • Using and reapplying the sunscreen and lip balm with a sun protection factor (SPF) of 30 and above
  • Wearing protective clothing and wide-brimmed hats
  • Using sunglasses that block ultraviolet A and ultraviolet B radiation
  • Avoiding sun-sensitizing medications

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Medically Reviewed on 4/14/2021
Centers for Disease Control and Prevention. Basic Information About Skin Cancer.

American Academy of Dermatology. Types of Skin Cancer.

Holtel MR. Skin Cancer - Melanoma. Medscape.