What Is Melanoma?
Melanoma, also called malignant melanoma, is one of the deadliest forms of skin cancer. It begins in cells called melanocytes. These are located in the upper layer of skin and produce the pigment that gives skin, hair and eyes their color.
Melanoma occurs when melanocytes are damaged and start to grow uncontrollably. If not detected early, the cancer can grow deep within the skin and reach the blood and lymphatic vessels. Once there, it can spread (metastasize) throughout the body. Melanoma that has spread to other tissues is called metastatic melanoma.
Types of Melanoma
Melanoma typically begins on the surface of the skin. This type of melanoma is called cutaneous melanoma. Other, rare types include:
Mucosal melanoma: Develops in mucus membranes that line the body, such as the mouth (oral melanoma), throat, genitals (vaginal melanoma and vulvar melanoma), gastrointestinal tract and anus (anal melanoma).
Ocular melanoma (eye melanoma): Develops in the eye.
Subungual melanoma (nail melanoma): Develops under and around the fingernails and toenails
What Causes Melanoma?
It’s not clear how all melanomas develop, but exposure to ultraviolet (UV) radiation plays a role, particularly in fair-skinned people. A history of sunburns, especially blistering sunburns as a child or teenager, increases the risk, as does the use of tanning beds.
Not all melanomas are caused by UV radiation exposure alone. While most melanomas develop on areas of sun-exposed skin, such as the head and legs, some occur in areas that sunlight never reaches.
Melanoma Risk Factors
Melanoma risk factors include:
- Fair skin that tans poorly or burns easily
- Red or blond hair
- Blue or green eyes
- Having many moles or 10 or more atypical moles
- A history of sunburns or indoor tanning
- Blood relatives (parents, children, siblings, cousins, aunts, uncles) who have had melanoma
- Immune system weakness due to disease, organ transplant or medication
- A history of melanoma or other skin cancer
- Being age 50 or older
Dermatologists strongly encourage everyone, especially people who have one or more of these risk factors, to perform regular skin self-examinations. Self-exams can help people recognize any skin changes that could be cancerous.
Signs of Melanoma
What does melanoma look like? That’s hard to answer because it can vary greatly in appearance. The ABCDE rules describe how melanoma often looks in the early stages. Melanomas tend to have one or more ABCDE traits, and some have several.
- A stands for ASYMMETRY. One half of the mole or spot doesn’t match the other half.
- B stands for BORDER. The mole or spot has an irregular, scalloped or poorly defined border.
- C stands for COLOR. The mole or spot is uneven in color and includes shades of tan, brown and black. There may be areas of white, red, pink, gray or blue.
- D stands for DIAMETER. Melanomas are usually larger than 6 millimeters (the size of a pencil eraser) when diagnosed, but they can be smaller.
- E stands for EVOLVING. The mole has changed in size, shape or color or a new lesion has developed.
When performing a skin self-exam, it’s helpful to keep in mind that normal moles are generally uniform in color, round to oval in shape and have a well-defined border. A skin care practitioner should examine all new growths and any mole that has one or more ABCDE traits.
Melanoma develops in an existing mole in just 20% to 30% of cases. When it does, the first sign is usually a change in the shape, color, size or texture of the mole. Other changes that could indicate melanoma include a mole that becomes painful or begins to bleed or itch.
In 70% to 80% of cases, melanoma arises as a new lesion. It most commonly appears on the head, neck or back (in men) and the back, arms or lower legs (in women), though it can appear anywhere.
When melanoma develops in people with dark skin, it often occurs in areas that get less sun, including the lower leg and the bottom of the foot or the palms (acral lentiginous melanoma).
Signs of subungual melanoma (nail melanoma) include dark brown or black vertical lines beneath the nail or a darker band of skin around the nail. The affected nail may start to separate from the nail bed or split down the middle.
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Atypical Mole vs. Melanoma
An atypical mole, or dysplastic nevi, is a mole that looks different from other moles but is benign (not cancerous). Atypical moles may have some of the same ABCDE traits of melanoma. For instance, they may be larger than other moles or different in color. People with 10 or more atypical moles have 12 times the risk of melanoma according to the Skin Cancer Foundation.
Melanoma can develop in any mole, including an atypical mole. If a dermatologist suspects that an atypical mole has become cancerous, he or she may perform a biopsy.
Treatment typically begins with surgical removal of the melanoma and some normal-looking skin around the cancer (a safety margin). With early detection, surgical removal may be the only treatment required. When melanoma is limited to the epidermis (top layer of skin), the cure rate with surgical removal is close to 100 percent.
If testing indicates that the melanoma has metastasized to the lymph nodes or other areas of the body, treatment may include additional surgery to remove the cancer, immunotherapy, radiation therapy, chemotherapy or clinical trials. If the melanoma is advanced, the patient often receives a combination of treatments.
Determining how far the cancer has spread is called staging. The melanoma stages are:
- Stage 0 melanoma (melanoma in situ): The melanoma is confined to the epidermis (top layer of skin).
- Stage 1 melanoma (stage I melanoma): The melanoma is confined to the skin and is no more than 2 millimeters thick; the skin may be intact or ulcerated (the top layer of skin is absent).
- Stage 2 melanoma (stage II melanoma): The melanoma is confined to the skin and is more than 1 millimeter thick and may be thicker than 4 millimeters; the skin may be intact or ulcerated (the top layer of skin is absent).
- Stage 3 melanoma (stage III melanoma): The melanoma has spread to one or more nearby lymph nodes or small areas of nearby skin.
- Stage 4 melanoma (stage IV melanoma): The melanoma has spread to internal organs, beyond the closest lymph nodes to other lymph nodes, or areas of skin far from the original tumor.
One way the melanoma stage is determined is by analyzing a tissue sample under a microscope. Sometimes a sentinel lymph node biopsy (SLNB) is performed. When melanoma spreads, it frequently travels to the closest lymph node, known as the sentinel node, first. Removing and analyzing that node helps doctors determine whether the cancer has spread.
One or more imaging techniques may also be used to determine if melanoma has spread beyond the original site. These include X-ray, ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET) and radio-isotopic scans of the bones or organs.
Protecting your skin from UV radiation can reduce the risk of melanoma.
- Before going outside, generously apply a broad-spectrum, water-resistant sunscreen with a sun protection factor (SPF) of 30 or more to all exposed skin. Reapply approximately every two hours, even on cloudy days, and after swimming or sweating.
- Wear protective clothing, such as a long-sleeved shirt, pants, a wide-brimmed hat and sunglasses.
- Seek shade when possible.
- Protect children from UV exposure by dressing them in protective clothing, applying sunscreen and encouraging them to play in the shade.
- Use extra caution near water, snow and sand. These surfaces reflect the sun and increase the chance of sunburn.
- Get vitamin D through a healthy diet that may include vitamin supplements. Don’t try to get vitamin D from the sun.
- Avoid tanning beds. If you want to look like you’ve been in the sun, consider using a sunless self-tanning product, but continue to use sunscreen.
How Common Is Melanoma?
More than 1 million people are living with melanoma. The lifetime risk of the disease is highest in Caucasians (about 2.6%). The lifetime risk is lower among Black people (0.1%) and Hispanic people (0.6%).
Is Melanoma Genetic?
Five to 10% of melanoma patients have a family history of the disease. People with at least one relative who had melanoma have a 2.2-fold risk of developing it.
Is Melanoma Curable?
Melanoma can be cured, especially when it’s caught and treated at an early stage. The five-year relative survival rate for patients with stage 0 melanoma is 97%. It drops to 10% in people with stage 4 (IV) melanoma.
Can Melanoma Recur?
Melanoma patients have a lifelong risk of developing new melanomas, especially if the melanoma was thick or had spread to nearby lymph nodes before treatment. Follow-up appointments with your dermatologist are essential.
Does Melanoma Hurt?
Melanoma usually isn’t painful; only 3.7% of melanoma patients report pain according to one study. Squamous cell cancers and basal cell cancers are more likely than melanoma to hurt.
Does Melanoma Itch?
Melanoma can itch, but typically it doesn’t. Only 15% of melanoma patients report itching.
How Fast Does Melanoma Spread?
Some metastatic melanomas metastasize very quickly, while others take more than five years to spread. A notable exception is nodular melanoma, the second most common type of cutaneous (skin) melanoma, which can spread to vital organs within months of detection. The main sign of nodular melanoma is a firm bump or node that rises above the surface of the skin.