Melanoma, the most serious type of skin cancer, develops in the cells (melanocytes) that produce melanin the pigment that gives your skin its color. Melanoma can also form in your eyes and, rarely, in internal organs, such as your intestines.
Although melanoma is not a new disease, evidence for its occurrence in antiquity is rather scarce. However, one example lies in a 1960s examination of nine Peruvian mummies, radiocarbon dated to be approximately 2400 years old, which showed apparent signs of melanoma: melanotic masses in the skin and diffuse metastases to the bones.
The French physician René Laennec was the first to describe melanoma as a disease entity. His report was initially presented during a lecture for the Faculté de Médecine de Paris in 1804 and then published as a bulletin in 1806. The first English language report of melanoma was presented by an English general practitioner from Stourbridge, William Norris in 1820. Norris was also a pioneer in suggesting a link between nevi and melanoma and the possibility of a relationship between melanoma and environmental exposures, by observing that most of his patients had pale complexions. He also described that melanomas could be amelanotic and later showed the metastatic nature of melanoma by observing that they can disseminate to other visceral organs.
The incidence of malignant melanoma has been increasing rapidly worldwide, and this increase is occurring at a faster rate than that of any other cancer except lung cancer in women. Queensland, Australia, has the highest incidence of melanoma in the world, approximately 57 cases per 100,000 people per year. Israel also has one of the highest incidences, approximately 40 cases per 100,000 people annually.
Melanoma is more common in whites than in blacks and Asians. The rate of melanoma in blacks is estimated to be one twentieth that of whites. White people with dark skin also have a much lower risk of developing melanoma than do those with light skin. The typical patient with melanoma has fair skin and a tendency to sunburn rather than tan. White people with blond or red hair and profuse freckling appear to be most prone to melanomas. In Hawaii and the southwestern United States, whites have the highest incidence, approximately 20-30 cases per 100,000 people per year.
The main types of melanoma are as follows:
Superficial spreading melanoma: This type accounts for about 70% of all cases of melanoma. The most common locations are the legs of women and the backs of men, and they occur most commonly between the ages of 30-50. (Note: Melanomas can occur in other locations and at other ages, as well.) These melanomas are flat or barely raised and have a variety of colors. Such melanomas evolve over one to 5 years and can be readily caught at an early stage if they are detected and removed. An “in situ” melanoma (malignant melanoma in situ) refers to a very thin superficial spreading melanoma that does not extend beyond the junction of the dermis and epidermis, the normal location for melanocytes.
Nodular melanoma: About 20% of melanomas begin as deeper, blue-black to purplish lumps. They may evolve faster and may also be more likely to spread. Untreated superficial spreading melanomas may become nodular and invasive.
Lentigo maligna: Unlike other forms of melanoma, lentigo maligna tends to occur on places like the face, which are exposed to the sun constantly rather than intermittently. Lentigo maligna looks like a large, irregularly shaped or colored freckle and develops slowly. It may take many years to evolve into a more dangerous melanoma or may never become a more invasive form. Because of the unpredictability of future behavior, removal is recommended.
There are also other rarer forms of melanoma that may occur, for example, under the nails (subungual), on the palms and soles (acral lentiginous), uveal or choroidal (ocular), oral or other mucosal areas such as the vulva or penis, or sometimes even inside the body such as the brain.
Factors that may increase your risk of melanoma include:
Fair skin: Having less pigment (melanin) in your skin means you have less protection from damaging UV radiation. If you have blond or red hair, light-colored eyes, and freckle or sunburn easily, you’re more likely to develop melanoma than is someone with a darker complexion. But melanoma can develop in people with darker complexions, including Hispanics and blacks.
A history of sunburn: One or more severe, blistering sunburns can increase your risk of melanoma.
Excessive ultraviolet (UV) light exposure: Exposure to UV radiation, which comes from the sun and from tanning lights and beds, can increase the risk of skin cancer, including melanoma.
Living closer to the equator or at a higher elevation: People living closer to the earth’s equator, where the sun’s rays are more direct, experience higher amounts of UV radiation than do those living in higher latitudes. In addition, if you live at a high elevation, you’re exposed to more UV radiation.
Having many moles or unusual moles: Having more than 50 ordinary moles on your body indicates an increased risk of melanoma. Also, having an unusual type of mole increases the risk of melanoma. Known medically as dysplastic nevi, these tend to be larger than normal moles and have irregular borders and a mixture of colors.
A family history of melanoma: If a close relative such as a parent, child or sibling has had melanoma, you have a greater chance of developing a melanoma, too.
Weakened immune system: People with weakened immune systems, such as those who’ve undergone organ transplants, have an increased risk of skin cancer.
Causes of melanoma
Melanoma occurs when something goes awry in the melanin-producing cells (melanocytes) that give color to your skin.
- Normally, skin cells develop in a controlled and orderly way — healthy new cells push older cells toward your skin’s surface, where they die and eventually fall off. But when some cells develop DNA damage, new cells may begin to grow out of control and can eventually form a mass of cancerous cells.
- Just what damages DNA in skin cells and how this leads to melanoma isn’t clear. It’s likely that a combination of factors, including environmental and genetic factors, causes melanoma. Still, doctors believe exposure to ultraviolet (UV) radiation from the sun and from tanning lamps and beds is the leading cause of melanoma.
- UV light doesn’t cause all melanomas, especially those that occur in places on your body that don’t receive exposure to sunlight. This indicates that other factors may contribute to your risk of melanoma.
Symptoms of melanoma
Unusual moles, sores, lumps, blemishes, markings, or changes in the way an area of the skin looks or feels may be a sign of melanoma or another type of skin cancer, or a warning that it might occur.
A normal mole is usually an evenly colored brown, tan, or black spot on the skin. It can be either flat or raised. It can be round or oval. Moles are generally less than 6 millimeters (about ¼ inch) across (about the width of a pencil eraser). Some moles can be present at birth, but most appear during childhood or young adulthood. New moles that appear later in life should be checked by a doctor.
Once a mole has developed, it will usually stay the same size, shape, and color for many years. Some moles may eventually fade away.
Most people have moles, and almost all moles are harmless. But it’s important to recognize changes in a mole – such as in its size, shape, or color – that can suggest a melanoma may be developing.
Possible signs and symptoms of melanoma
The most important warning sign of melanoma is a new spot on the skin or a spot that is changing in size, shape, or color. Another important sign is a spot that looks different from all of the other spots on your skin (known as the ugly duckling sign). If you have one of these warning signs, have your skin checked by a doctor.
The ABCDE rule is another guide to the usual signs of melanoma. Be on the lookout and tell your doctor about spots that have any of the following features:
A is for Asymmetry: One half of a mole or birthmark does not match the other.
B is for Border: The edges are irregular, ragged, notched, or blurred.
C is for Color: The color is not the same all over and may include different shades of brown or black, or sometimes with patches of pink, red, white, or blue.
D is for Diameter: The spot is larger than 6 millimeters across (about ¼ inch – the size of a pencil eraser), although melanomas can sometimes be smaller than this.
E is for Evolving: The mole is changing in size, shape, or color.
Some melanomas don’t fit these rules. It’s important to tell your doctor about any changes or new spots on the skin, or growths that look different from the rest of your moles.
Other warning signs are:
- A sore that doesn’t heal
- Spread of pigment from the border of a spot into surrounding skin
- Redness or a new swelling beyond the border of the mole
- Change in sensation, such as itchiness, tenderness, or pain
- Change in the surface of a mole – scaliness, oozing, bleeding, or the appearance of a lump or bump
Be sure to show your doctor any areas that concern you and ask your doctor to look at areas that may be hard for you to see. It’s sometimes hard to tell the difference between melanoma and an ordinary mole, even for doctors, so it’s important to show your doctor any mole that you are unsure of.
Diagnosis and test
Sometimes cancer can be detected simply by looking at your skin, but the only way to accurately diagnose melanoma is with a biopsy. In this procedure, all or part of the suspicious mole or growth is removed, and a pathologist analyzes the sample.
Biopsy procedures used to diagnose melanoma include:
Punch biopsy: During a punch biopsy, your doctor uses a tool with a circular blade. The blade is pressed into the skin around a suspicious mole, and a round piece of skin is removed.
Excisional biopsy: In this procedure, the entire mole or growth is removed along with a small border of normal-appearing skin.
Incisional biopsy: With an incisional biopsy, only the most irregular part of a mole or growth is taken for laboratory analysis.
The type of skin biopsy procedure you undergo will depend on your situation. Doctors prefer to use punch biopsy or excisional biopsy to remove the entire growth whenever possible. Incisional biopsy may be used when other techniques can’t easily be completed, such as if a suspicious mole is very large.
Skin cancer screening
Ask your doctor whether you should consider periodic screening for skin cancer. You and your doctor may consider screening options such as:
Skin exams by a trained professional: During a skin exam, your doctor conducts a head-to-toe inspection of your skin.
Skin exams you do at home: A self-exam may help you learn the moles, freckles and other skin marks that are normal for you so that you can notice any changes. It’s best to do this standing in front of a full-length mirror while using a hand-held mirror to inspect hard-to-see areas. Be sure to check the fronts, backs and sides of your arms and legs. In addition, check your groin, scalp, fingernails, soles of your feet and spaces between your toes.
Treatment and medications
The good news is that even stage 4 melanoma can be treated. The sooner the cancer is found, the sooner it can be removed and the higher your chances are for recovery. Stage 4 melanoma also has the most treatment options, but these options depend on:
- where the cancer is
- where the cancer has spread
- your symptoms
- how advanced the cancer has become
- your age and overall health
How you respond to treatment also affects your treatment options. The five standard treatments for melanoma are:
Surgery: to remove the primary tumor and affected lymph nodes
Chemotherapy: a drug treatment to stop growth of cancer cells
Radiation therapy: the application of high-energy X-rays to inhibit growth and cancer cells
Immunotherapy: treatment to boost your immune system
Targeted therapy: the use of drugs or other substances to attack cancer drugs
Other treatments may also depend on where the cancer has spread to. Your doctor will discuss your options with you to help map out a treatment plan.
Prevention of melanoma
There is no sure way to prevent melanoma. Some risk factors such as your age, gender, race, and family history can’t be controlled. But there are things you can do that could lower your risk of getting melanoma and other skin cancers.
Limit your exposure to ultraviolet (UV) rays
The most important way to lower your risk of melanoma is to protect yourself from exposure to UV rays. Practice sun safety when you are outdoors.
Simply staying in the shade is one of the best ways to limit your UV exposure.
Slip! Slop! Slap!… and Wrap”
If you are going to be in the sun, this catchphrase can help you remember some of the key steps you can take to protect yourself from UV rays:
- Slip on a shirt.
- Slop on sunscreen.
- Slap on a hat.
- Wrap on sunglasses to protect the eyes and sensitive skin around them.
Avoid using tanning beds and sunlamps
Many people believe the UV rays of tanning beds are harmless. This is not true. Tanning lamps give out UV rays, which can cause long-term skin damage and can contribute to skin cancer. Tanning bed use has been linked with an increased risk of melanoma, especially if it is started before a person is 30. Most dermatologists (skin doctors) and health organizations recommend not using tanning beds and sun lamps.
Protect children from the sun
Children need special attention, since they tend to spend more time outdoors and can burn more easily. Parents and other caregivers should protect children from excess sun exposure by using the steps above. Children need to be taught about the dangers of too much sun exposure as they become more independent.
To learn more about sun safety
For more on how to protect yourself and your family from UV exposure, see Skin Cancer Prevention and Early Detection.
Watch for abnormal moles
Checking your skin regularly may help you spot any new or abnormal moles or other growths and show them to your doctor before they even have a chance to turn into skin cancer.
Certain types of moles are more likely to develop into melanoma (see Melanoma Skin Cancer Risk Factors). If you have moles, depending on how they look, your doctor may want to watch them closely with regular exams or may remove some of them if they have features that suggest they might change into a melanoma.
Routine removal of many moles is not usually recommended as a way to prevent melanoma. Some melanomas develop from moles, but most do not. If you have many moles, getting careful, routine exams by a dermatologist, along with doing monthly skin self-exams are, might be recommended.
If you find a new, unusual, or changing mole, you should have it checked by a doctor experienced in recognizing skin cancers. See Signs and Symptoms of Melanoma Skin Cancer for descriptions of what to look for.
Avoid weakening your immune system (when possible)
Having a weakened immune system increases your risk of getting melanoma and other types of skin cancer.
Infection with HIV, the virus that causes AIDS, can weaken the immune system. Avoiding known risk factors for HIV infection, such as intravenous (IV) drug use and having unprotected sex with many partners, might lower your risk of skin cancer and many other types of cancer. (For more information, see HIV Infection, AIDS, and Cancer.)
Some people need to take medicines to suppress their immune system. This includes people who have had organ transplants and some people with autoimmune diseases. People with cancer also sometimes need to take medicines such as chemotherapy that can lower their immune function. For these people, the benefit from taking these medicines will likely far outweigh the small increased risk of getting skin cancer.