Melanoma is a malignant form of skin cancer that occurs in cells called melanocytes, which produce pigments that give skin its color. Melanoma usually appears as an irregular brown, black and/or red spot, or an existing mole that begins to change color, size or shape. While melanoma only represents about 3 percent of all skin cancers, it has the highest death rate of all types, and is more likely to metastasize (spread).
Melanoma appears most frequently on the trunk area in fair-skinned men and on the lower leg 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 potentially curable.
There are four major types of cutaneous melanoma: Superficial spreading melanoma is the most common form of the disease, responsible for about 70 percent of cases. It generally originates in a pre-existing mole.
Nodular melanoma is the second most common, responsible for 15 to 30 percent of cases. Nodular melanomas are more aggressive and usually develop more rapidly than superficial melanomas.
Lentigo maligna melanoma appears as large, flat lesions most commonly found on the faces of light-skinned women over the age of 50. This form of melanoma, responsible for about 4 percent to 10 percent of cases, has a lower risk of metastasis than other types.
Acral lentiginous melanoma occurs on the palms, soles of the feet or beneath the nail beds. They account for only 2 percent to 8 percent of melanomas in fair-skinned patients, but up to 60 percent of melanomas in darker-skinned patients. Acral lentiginous melanomas are extremely aggressive and large, with an average diameter of three centimeters.
Mucosal melanomas are rare, making up only about 1 percent of all diagnosed melanoma cases. This disease occurs in mucosal tissue, which lines body cavities and hollow organs. The most common sites for mucosal melanoma are the head and neck region (including the nasal cavity, mouth and esophagus), as well as the rectum, urinary tract and vagina. Mucosal melanomas can be very hard to detect, and even when diagnosed and treated, the outlook is poor.
Because the eyes contain melanocytes, or pigment-producing cells, they can be susceptible to melanoma. Read more about the two types of ocular melanoma:
- Uveal Melanoma
- Conjunctival Melanoma
Symptoms of skin cancer vary from person to person and may include a:
- Change on the skin, such as a new spot or one that changes in size, shape or color
- Sore that doesn’t heal
- Spot or sore that changes in sensation, itchiness, tenderness or pain
- Small, smooth, shiny, pale or waxy lump
- Firm red lump that may bleed or develops a crust
- Flat, red spot that is rough, dry or scaly
Many of these symptoms are not cancer, but if you notice one or more of them for more than two weeks, see your doctor.
Skin cancer can't be diagnosed merely by looking at it. If a mole or pigmented area of the skin changes or looks abnormal, your doctor may choose to biopsy the mark, taking a tissue sample for a pathologist to examine. Suspicious areas should not simply be shaved off or cauterized (destroyed with a hot instrument, an electrical current or a caustic substance). A biopsy should be performed first to determine if the area is malignant.
Several techniques are used to perform skin biopsies. For skin cancer, your doctor will most likely use a technique known as local excision, in which the entire suspicious area is removed under local anesthetic. Depending on the size and location of the suspicious area on your body, you may have this type of biopsy done in a doctor's office or possibly as an outpatient at a hospital. Your doctor will put in stitches to close the excision and cover the area with a bandage.
Some doctors use other biopsy techniques called punch biopsies or shave biopsies. In a punch biopsy, the doctor uses a tool to punch through the suspicious area and extract a round cylinder of tissue. In a shave biopsy, the doctor simply shaves off a piece of the growth. Both of these types of biopsies are usually done in a doctor's office. If the tissue is malignant, further excision will be necessary. The sample of skin is sent to a pathologist, who looks at the tissue under a microscope to check for cancer cells.
When you are diagnosed with melanoma, your doctor will tell you what stage melanoma you have. "Stage" is a way to describe the severity of a cancer by incorporating information about its location, size, whether it has spread to nearby lymph nodes and whether it has metastasized to other parts of the body.
In the case of melanoma, stages I and II are based mainly on the thickness of the cancer and how many layers of skin it has invaded. Stages III and IV are based on how far the melanoma has spread from the skin. Staging is based on a combination of physical examination, biopsy, and investigation of the lymph nodes and other parts of the body.
After melanoma has been diagnosed, tests are done to find out if cancer cells have spread within the skin or to other parts of the body.
Stage 0 (Melanoma in situ): Does not reach below the surface of the skin.
Stage IA melanoma is less than one millimeter thick and has not ulcerated. It is most likely present only in the top layer of the skin.
Stage IB melanoma also may be less than one millimeter thick but has ulcerated (become an open sore) and may have grown into deeper layers of the skin.
Stage IIA melanoma is either one to two millimeters thick with ulceration or two to four millimeters thick with no ulceration.
Stage IIB melanoma is either two to four millimeters thick with ulceration or more than four millimeters thick without ulceration.
Stage IIC melanoma is more than four millimeters thick with ulceration.
Stage III melanoma has spread to the lymph system or directly into the lymph nodes near the cancer, and may also have spread directly from the original tumor to areas more than four centimeters away (but not to farther lymph nodes).
Stage IV melanoma has metastasized to more distant lymph nodes and/or to other organs.
Melanomas Less Than One Millimeter Thick A thin melanoma—one that is less than one millimeter thick (stage 1A or 1B)—is usually treated with a wide local excision of the skin, in which the surgeon cuts out the melanoma and an area around it. The amount of skin that is removed and the degree of scarring relate to the size of the lesion or mole. Generally, these patients do not need adjuvant therapy such as chemotherapy, immunotherapy or radiation therapy.
Depending on the size of the melanoma, the local excision may be an inpatient or outpatient procedure, usually with local anesthesia. The area may require stitches, and recovery can last a few weeks. The severity of the scar depends on the size, depth and location of the melanoma.
Melanomas More Than One Millimeter Thick
Melanomas one millimeter or more in thickness are considered somewhat more serious than thin melanomas because they are more likely to spread to other areas of the body. For larger melanomas, in addition to a wide local excision, a surgeon will often do a lymph node biopsy to check whether the cancer cells have spread. In a lymph node biopsy, lymph nodes in the area of the cancer are surgically removed to see whether they contain cancer. Your surgeon may opt to do a sentinel lymph node biopsy, in which only the closest lymph node to the tumor is removed to check for cancer. If the lymph node closest to the tumor is cancer free, then the other lymph nodes do not need to be checked or removed.
Metastatic Melanoma (Stage IV)
At this stage, melanoma has spread into distant skin or lymph nodes or other organs such as the lungs, liver or brain. Surgeons do not usually operate to remove these metastases. Even if large metastases can be removed, there are very likely smaller ones in other places that would be missed. However, treatment may still be able to improve symptoms and extend life. A doctor may recommend system-wide chemotherapy or immunotherapy to improve a patient's quality of life.
A number of immunotherapy medications may be injected into the skin to treat skin cancers. The most commonly used is interferon-alpha. Interferon works by stimulating the body's immune response to destroy skin cancer tissue. The tumor progressively shrinks. The destruction is relatively specific, and healthy tissue is usually spared. Redness, inflammation and flu-like symptoms may occur as part of the immune system response. It may take a series of injections, spaced several months apart, to eradicate a larger skin cancer.
Interferon can also be used for people whose melanoma has spread beyond the original cancer site to one or more lymph nodes, in order to prevent or delay melanoma recurrences. In this case, it is given for a year to decrease the risk that melanoma will return. For the first four weeks, a high dose of interferon is administered intravenously five days a week; for the rest of the year, a lower dose is injected under the skin three days a week, usually by the patient.
If a large area of skin must be removed during surgery, a skin graft may be done to reduce scarring. In a skin graft, the surgeon first numbs and then removes a patch of healthy skin from another part of the body, such as the upper thigh, and then uses it to replace the skin that is removed to cover the wound from surgery. This is done at the same time as the skin cancer surgery. The surgeon first numbs and then removes a patch of healthy skin from another part of the body. The patch is then used to cover the area where skin cancer was removed. If you have a skin graft, you may have to take special care of the area until it heals.
Radiation therapy may be used to treat all types of skin cancers. Radiation therapy uses high-energy photons (or electrons) to destroy tumors. It targets the tumor site as well as a surrounding margin of skin. Shields are custom made for each patient to protect as much of the non-targeted tissue as possible. Radiation therapy can be adjusted to be superficial or deeply penetrating, which means it can treat a variety of tumors. Properly performed, radiation therapy can achieve high cure rates with little or no scarring. Patients who have multiple lesions in one region of skin may have radiation therapy instead of surgery. Radiation therapy may be combined with chemotherapy, in chemoradiation, for advanced tumors.
Melanoma patients have a high risk of developing new melanomas. Some also are at risk of a recurrence of the original melanoma in nearby skin or in other parts of the body. The chance of recurrence is greater for patients whose melanoma was thick or had spread to nearby tissue than for patients with very thin melanomas. Family members of people with melanoma should also have regular checks for melanoma.
To increase the chance of detecting a new or recurrent melanoma as early as possible, patients should follow their doctor's schedule for regular check-ups.
Follow-up care for those who have a high risk of recurrence may include X-rays, blood tests and scans of the chest, liver, bones and brain. It is especially important for patients who have dysplastic nevi (atypical moles) and a family history of melanoma to have frequent checkups. People with melanoma also should monitor their own skin carefully for changes.