Melanoma is a skin cancer that starts in melanocytes (cells that make melanin), which give skin its pigment, or color. Sometimes these cells change, often because of damage caused by sun exposure. Over time, this damage may result in cancer.
Approximately 70,000 new cases of invasive melanoma are diagnosed in the United States each year. While melanoma accounts for only 3% of all types of the skin cancer, it has the highest death rate of all types and is more likely to spread (metastasize) in the body. It is also one of the most frequently occurring cancers in young adults ages 20 to 30, and is the main cause of cancer death in women 25 to 30 years old.
Melanoma usually appears as an:
- Irregular brown, black and/or red spot or
- Existing mole that begins to change color, size or shape
Melanoma appears most commonly on the trunk area in fair-skinned men and on the lower legs in fair-skinned women. In dark-skinned people, melanoma appears most frequently on the palms, the soles of the feet and the skin under nails. If caught early, melanoma is often curable.
Melanoma is divided into several types. The treatment and outlook for each is different.
There are four major types of cutaneous melanoma:
Superficial spreading melanoma:
- Most common melanoma type
- About 70% of cases
- Usually starts in a pre-existing mole
- Second most common melanoma type
- 15% to 30% of cases
- More aggressive and usually develops quicker than superficial spreading melanomas
Lentigo maligna melanoma:
- Appears as large, flat lesions
- Most commonly found on the faces of light-skinned women over 50
- 4% to 10% of cases
- Lower risk of spreading than other melanoma types
Acral lentiginous melanoma:
- Occurs on the palms, soles of the feet or beneath the nail beds
- 2% to 8% of melanomas in fair-skinned patients
- Up to 60% of melanomas in darker-skinned patients
- Large, with an average diameter of 3 centimeters
- About 1% of melanoma cases
- Occurs in mucosal tissue, which lines body cavities and hollow organs
- Most common sites are head and neck region (including the nasal cavity, mouth and esophagus), rectum, urinary tract and vagina
- Can be very difficult to detect
- Even when diagnosed and treated, prognosis is often poor
Because the eyes contain melanocytes, they can be susceptible to melanoma. Read more about the two types of ocular melanoma:
Melanoma Risk Factors
Anything that increases your chance of getting melanoma is a risk factor.
Sun damage, especially a history of peeling sunburns, is the main risk factor for melanoma. Artificial sunlight from tanning beds causes the same risk for melanoma as natural sunlight.
Other risk factors for melanoma include:
- Fair complexion: People with blond or red hair, light skin, blue eyes and a tendency to sunburn are at increased risk.
- Previous melanoma
- Moles (nevi): Having a lot of benign (non-cancer) moles
- Family history of melanoma
- Atypical mole and melanoma syndrome (AMS): Previously known as dysplastic nevus syndrome, AMS is characterized by large numbers of atypical moles. If you have AMS, you and your family members should be screened regularly
Not everyone with risk factors gets melanoma.
While signs and symptoms of melanoma vary from person to person, the ABCDEFs of melanoma symptoms are an easy way to learn the early signs of melanoma.
Asymmetry: Is one side of the mole different than the other?
Border irregularity: Are the edges ragged or irregular?
Color variation: Is the mole getting darker? Is part of it changing color or does it contain several colors?
Diameter: Is the mole bigger than the diameter of a pencil eraser?
Evolution: Is the mole growing in width or height?
Feeling: Has the sensation around a mole or spot changed?
Show any suspicious skin area, non-healing sore or new or changing mole or freckle to your doctor right away.