What Is Melanoma?

Melanoma is a type of skin cancer that begins in melanocytes — the cells responsible for producing melanin, the pigment that gives skin its color. While it accounts for only about 1% of all skin cancer cases — far fewer than basal cell carcinoma or squamous cell carcinoma — melanoma causes the vast majority of skin cancer deaths because of its ability to spread to other organs if not caught early.

Melanoma most commonly appears on the skin, but it can also develop in the eyes (ocular melanoma) and, rarely, in other areas such as the digestive tract or nasal passages.

The United States sees approximately 100,000 new melanoma diagnoses each year. Florida, with its year-round high UV index, ranks among the highest states for melanoma incidence.

Symptoms

Melanoma often begins as an unusual mole or develops in an existing mole that changes in appearance. The classic warning signs follow the ABCDE rule:

A — Asymmetry: One half of the mole doesn't match the other
B — Border: Irregular, ragged, notched, or blurred edges
C — Color: Variation in color — shades of brown, black, pink, red, white, or blue within the same lesion
D — Diameter: Larger than 6mm (about the size of a pencil eraser), though melanomas can be smaller
E — Evolving: Any change in size, shape, color, or a new symptom such as bleeding, itching, or crusting

Some melanomas don't follow these rules. Nodular melanoma, for example, can appear as a small, firm bump that grows quickly. Amelanotic melanoma has little or no color, making it harder to identify.

Pay attention to any new or changing skin lesion, even if it looks different from these descriptions. When in doubt, have it evaluated promptly.

Causes & Risk Factors

Melanoma develops when DNA damage in melanocytes triggers uncontrolled cell growth. The primary cause is ultraviolet (UV) radiation from sunlight and tanning beds, though melanoma can also occur in areas that receive little sun exposure.

Key risk factors include:

Fair skin, freckles, or light hair: Less melanin means less natural UV protection
History of sunburns: Blistering burns — especially before age 18 — significantly increase lifetime risk
Family history: Having a first-degree relative with melanoma raises your risk two- to threefold
Personal history: Having had a melanoma or other skin cancer increases the risk of developing another
Many moles: Having more than 50 moles, or atypical (dysplastic) moles, raises risk
Weakened immune system: From medications, HIV, or organ transplantation
Geographic factors: Living in sun-intense climates like Florida, or at high altitude

Diagnosis

A dermatologist diagnoses melanoma through:

Visual examination: Evaluating the lesion using dermoscopy (a magnifying device with polarized light) to see structures beneath the skin surface
Full-body skin exam: Checking all skin surfaces, including the scalp, between the toes, and other less visible areas
Biopsy: If a lesion is suspicious, a sample is removed and examined under a microscope by a pathologist — this is the only definitive way to diagnose melanoma
Staging: If melanoma is confirmed, additional testing determines how far it has spread, which guides treatment

Breslow thickness (how deep the melanoma has grown into the skin) is the most important factor in prognosis. Thinner melanomas have substantially better outcomes, which is why early detection is critical.

Treatment Options

Treatment depends on the stage and location of the melanoma:

Surgical excision: The primary treatment for most melanomas. The lesion is removed along with a margin of healthy tissue. Most early-stage melanomas are cured with surgery alone.
Sentinel lymph node biopsy: For melanomas of a certain depth, nearby lymph nodes are sampled to check for spread
Mohs micrographic surgery: For melanomas in cosmetically sensitive or anatomically complex locations
Immunotherapy: For advanced melanoma, drugs that help the immune system recognize and attack cancer cells (e.g., checkpoint inhibitors)
Targeted therapy: For melanomas with specific gene mutations (e.g., BRAF), targeted drugs can be effective
Radiation: Used in certain situations, particularly for melanoma that has spread to the brain or bones

Prevention

You cannot completely eliminate melanoma risk, but you can significantly reduce it:

Apply broad-spectrum SPF 30+ sunscreen daily, including on cloudy days, and reapply every two hours outdoors
Seek shade between 10 AM and 4 PM, when UV radiation is strongest
Wear protective clothing: Long sleeves, wide-brimmed hats, and UV-blocking sunglasses
Avoid tanning beds: They emit UV radiation that directly damages DNA in skin cells
Perform monthly skin self-exams: Look for new lesions or changes to existing ones
Schedule annual full-body skin checks with a board-certified dermatologist — for those with many moles, Total Body Photography creates a baseline to track changes over time

When to See a Doctor

See a dermatologist promptly if you notice:

Any mole or skin lesion that is new, changing, or unusual
A mole that bleeds, itches, or won't heal
Any skin lesion that concerns you, even if it doesn't match the ABCDE criteria

Early melanoma caught at Stage I has a 5-year survival rate greater than 98%. Melanoma diagnosed after it has spread to distant organs has a 5-year survival rate of approximately 30%. The difference is almost entirely about timing. If something looks wrong, don't wait for your next annual exam — call your dermatologist.

References

Siegel RL, Miller KD, Wagle NS, Jemal A. Cancer statistics, 2023. CA: A Cancer Journal for Clinicians. 2023;73(1):17–48. doi:10.3322/caac.21763
American Academy of Dermatology Association. Melanoma: Overview. aad.org
Gershenwald JE, Scolyer RA, Hess KR, et al. Melanoma staging: Evidence-based changes in the American Joint Committee on Cancer eighth edition cancer staging manual. CA: A Cancer Journal for Clinicians. 2017;67(6):472–492. doi:10.3322/caac.21409
Shoo BA, Kashani-Sabet M. Melanoma arising in African-, Asian-, Latino- and Native-American populations. Seminars in Cutaneous Medicine and Surgery. 2009;28(2):96–102. doi:10.1016/j.sder.2009.04.005
National Cancer Institute. SEER Cancer Statistics: Melanoma of the Skin. seer.cancer.gov
Tsao H, Atkins MB, Sober AJ. Management of cutaneous melanoma. New England Journal of Medicine. 2004;351(10):998–1012. doi:10.1056/NEJMra041245
Centers for Disease Control and Prevention. Skin Cancer Statistics. cdc.gov/cancer/skin