Melanoma is the most serious form of skin cancer, compared to basal cell and squamous cell carcinoma. But most melanomas can be cured if they’re found and treated early, before they spread. So it’s important to learn the warning signs and how the disease is diagnosed.
- What is melanoma?
- Types and pictures
- Risk factors
- How common is melanoma?
- Next steps
What is melanoma?
Melanoma is cancer that begins in melanocytes, cells that make melanin, the pigment that determines your natural skin color.
Cancer cells do not respond like healthy cells to signals that regulate cell growth, division and death. They also don’t stop growing after they have reached normal boundaries. Instead they grow into a tumor, which may invade surrounding layers of tissue and spread to other organs.
Normally, melanocytes are at the bottom of your epidermis, the outer layer of your skin. Abnormal melanocytes that have turned into cancer may grow:
- Up, forming a raised bump that you can see and feel
- Down into the second layer of your skin, the dermis
- Out along your skin
If melanoma cells enter your blood vessels or lymph vessels, they may spread to other parts of your body too.
Types and pictures of melanoma
There are four basic types of melanoma.
Superficial spreading melanoma
This is the most common type of melanoma. It travels along the top layer of skin for a long time before going deeper. It can be found almost anywhere on the body but is more common on areas exposed to more ultraviolet (UV) light, from either the sun or an artificial source, like a tanning bed.
Appearance: The first sign is a flat or slightly raised, discolored patch with irregular borders. The color varies and might include areas of tan, brown, black, red, blue or white.
This type grows into the dermis more quickly than other types do.
Appearance: Looks and feels like a firm bump, often black but occasionally blue, gray, white, brown, tan, red or your usual skin tone.
This type of melanoma stays close to the skin’s surface for a long time. It is more often found in older people on skin chronically exposed to and damaged by the sun.
Appearance: Usually appears as a flat or mildly elevated mottled tan, brown or dark brown discoloration.
Acral lentiginous melanoma
This type spreads near the surface before growing deeper into the skin. It is not related to UV light and is usually found under the nails, on the palms or on the soles of the feet. Overall, this is the least common type of melanoma, but it’s the most common type in people with darker skin.
Appearance: A black or brown discoloration.
Symptoms of melanoma
In addition to watching for skin lesions or other changes described above:
- Learn how to examine your skin and which general skin cancer warning signs to look for.
- Read about symptoms of other forms of skin cancer, and see pictures.
If you have not been diagnosed with skin cancer but you are concerned about your moles or other pigmented lesions, you may want to make an appointment for an evaluation at the Dermatologic Clinic at UWMC-Roosevelt, especially if you are at risk for melanoma.
If you have an abnormal-looking growth on your skin that might be melanoma, your doctor will:
- Review and ask about your medical history and family history.
- Ask about your sun exposure, lifestyle, medicines and other risk factors.
- Ask about your symptoms, when the lesion first appeared and if it has changed in size or appearance.
- Perform a thorough physical exam and check the skin lesion, any other suspicious moles or marks and your lymph nodes.
If your doctor is concerned that a lesion might be cancer, they may recommend a skin biopsy. This involves taking a sample of suspicious tissue so a pathologist can examine the cells under a microscope to look for cancer cells.
Common types of skin biopsies include:
- Shave biopsy — A sterile razor blade is used to shave off the lesion.
- Punch biopsy — An instrument called a punch is used to remove a circle of tissue from the lesion.
- Excisional biopsy — A scalpel is used to remove the entire growth.
Sentinel lymph node mapping and biopsy
If you’ve been diagnosed with melanoma and your care team is concerned that cancer cells might have spread, your doctor will want you to have a sentinel lymph node biopsy. In this procedure:
- A tracer substance and a dye are injected near your tumor.
- The substance flows through lymph ducts to the first lymph node or nodes where cancer cells are likely to spread (sentinel nodes).
- Your surgeon removes only the nodes where the substance appears.
- A pathologist checks the sentinel nodes for cancer.
Imaging studies and lab tests
Your doctor might recommend other tests or scans to learn more about your condition, especially if your tumor is deep or cancer is in your lymph nodes. These may include a computed tomography (CT) scan, chest X-ray, positron emission tomography (PET) scan, magnetic resonance imaging (MRI) scan or bone scan and tissue, blood or urine tests.
Stages of melanoma
Staging is the process of finding out whether your cancer has spread and, if so, to what extent. This helps guide your treatment.
Melanoma is assigned a stage from I to IV, with I being the least advanced and IV being the most advanced.
- In stages I and II, melanoma is only in the skin.
- In stage III, nearby lymph nodes are involved.
- Stage IV melanoma affects distant organs in other parts of the body.
Risk factors for melanoma
Everyone is at some risk for melanoma and other skin cancers, but certain factors increase your risk. The major risk factor by far is exposure to UV light, especially if you have fair skin.
People with darker skin are at lower risk because they have more melanin, which provides some protection. But people with any skin tone can get melanoma.
Read details about skin cancer risk factors, including ways that UV-exposure increases your risk.
In addition, the following factors may affect your risk for melanoma specifically:
- Family history of certain cancers — You are at increased risk if you have family members with a history of melanoma (especially if multiple relatives had it), pancreatic cancer, astrocytoma (a form of brain cancer), uveal melanoma (involving the eye) or mesothelioma.
- Moles — A mole (nevus) is a benign (noncancerous) collection of pigment cells. There’s active scientific discussion of whether moles turn into cancer. Let your doctor know if a mole becomes itchy, and check your body regularly for changing moles or other possible warning signs of skin cancer.
- Dysplastic (atypical) nevi — These moles develop from childhood on through adulthood and often run in families. Lifetime melanoma risk is higher in people with dysplastic nevi.
How common is melanoma?
Overall, skin cancers are the most common cancers in the United States. But melanoma is less common than the other two major types, basal cell and squamous cell carcinoma.
Each year about 91,000 people in the U.S. are diagnosed with melanoma of the skin, according to the American Cancer Society. By comparison, about 3.3 million are diagnosed with one or more basal cell or squamous cell carcinomas.
- Request an appointment to see an SCCA melanoma expert.
- Learn about melanoma treatment at SCCA.
- Read stories of people who’ve had melanoma.
- Find resources and support for new SCCA patients.