What is melanoma?
Melanoma is a type of skin cancer that starts in the skin’s pigment cells (melanocytes), which give the skin its color. Melanoma is much less common than nonmelanoma skin cancer, but has a higher chance of spreading to other sites of the body (metastasizing). In general, though, skin cancers are highly treatable if they are detected and treated early, mainly with surgical removal.
Most melanomas form in the skin, the body’s largest organ. The skin’s layers include:
- Epidermis: The top layer.
- Dermis: This layer below the epidermis contains blood vessels and lymph channels.
- Subcutis: This layer is also called the hypodermis or subcutaneous fat and also contains lymph vessels.
How does melanoma skin cancer develop?
Melanoma occurs when melanocytes mutate (abnormally change) and grow out of control. This is often related to excessive exposure to ultraviolet (UV) light from natural sunlight or artificial sources, such as indoor tanning beds. The abnormal cells form a spot or lesion that’s usually visible and colored on top of the skin. The spot can be entirely new or evolve from an existing mole on the skin, although melanomas don’t arise from pre-existing moles.
The vast majority of melanomas on the skin (called cutaneous melanomas) are diagnosed before they grow into surrounding areas or spread to other parts of the body (metastasize). Others may grow into nearby tissues (mainly regional lymph nodes) or metastasize to distant sites, like the lungs, liver, or brain.
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Understanding Melanoma
Melanoma Symptoms
People often notice melanoma when it forms a new or changing spot (lesion) on the skin’s top layer. The spot may look or feel different from other moles or freckles, especially if it:
- Is asymmetrical (one half doesn’t match the other)
- Has an uneven border
- Has unusual colors (varying shades of tan, brown, black, or pink)
- Changes in diameter (grows larger)
- Looks like it’s becoming elevated
- Doesn’t match a person’s other moles
Melanomas usually appear on sun-exposed areas of the skin, especially the face, ears, neck, chest, back, and lower legs. However, they can also develop in the eye, on the palms of the hands and soles of the feet, and beneath fingernails and toenails. Melanomas that aren’t related to UV light (like acral melanomas) are the most common type in people with darker skin tones. (Talk to your doctor if you see any new or changing lesions in these areas or anywhere on your skin.
Melanoma Risk Factors
Certain factors can increase your risk of developing melanoma. Having one or more risk factors does not mean you will develop skin cancer, and some people with no risk factors develop the disease.
Early and ongoing exposure to ultraviolet (UV) light from the sun and tanning beds is the most common cause of melanoma in people with lighter skin tones. Other risk factors include:
- Sun sensitive skin/tendency to sunburn, such as people with red hair
- Presence of many moles, especially larger moles
- Family history of melanoma
Melanoma Skin Cancer Types
Types of melanoma include:
- Superficial spreading melanoma: This is the most common type of melanoma, especially in people younger than 50 and those with many moles.
- Nodular melanoma: This melanoma type can appear as an elevated pink, tan, or brown bump that tends to grow and bleed.
- Lentigo maligna melanoma: This type most often appears in people older than age 60 or on chronically sun-damaged areas of the face, ears, scalp, neck, and arms.
- Acral lentiginous melanoma: This type of melanoma is the most common in darker-skinned people, who are less sensitive to the sun than those with lighter skin. It typically develops on the palms of the hands, soles of the feet, or beneath fingernails or toenails.
- Ocular melanoma: This rare melanoma subtype develops in the deeper layers of the eyes.
Melanoma Skin Cancer Stages
Staging is a process that reveals if cancer has spread beyond the skin to other sites of the body, and, if so, how far. Understanding the melanoma’s stage helps your medical team determine your prognosis (probable outcome based on large data sets of similar stage cancers) and the optimal treatment plan.
For melanoma, Stages 0 and 1 describe early stages of disease, and Stages 2 through 4 indicate more advanced stages. In general terms, melanoma skin cancer stages are:
- Stage 0: Called melanoma in situ; cancerous cells are confined to the top layer of the skin (the epidermis).
- Stage 1: Cancer is considered invasive. It has spread deeper into the skin (up to 2 mm thickness in the dermis) but not to the lymph nodes or other body parts. The tumor’s thickness determines the surgical treatment.
- Stage 2: The tumor is thicker than 2 millimeters but has not spread to the lymph nodes or other body parts. Stage 2 tumors may have ulceration (breakdown of the skin’s surface).
- Stage 3: Cancer is in nearby (regional) lymph nodes but not distant lymph nodes or organs.
- Stage 4: Cancer has spread to distant lymph nodes or other organs (like the liver, lungs, brain).
Diagnosis
To establish or confirm a diagnosis, your doctor reviews your health records and completes a physical exam, particularly of your skin and lymph nodes. Your doctor may recommend certain tests, including:
During a biopsy, your doctor (usually a dermatologist) removes as much of the visible skin tumor as possible. A dermatopathologist examines the tissue under a microscope to determine whether the cells are normal or cancerous.
Your doctor may recommend genetic testing if you have a family history of melanoma or a confirmed gene mutation related to melanoma. Genetic testing can show whether you have gene mutations that may be targeted by drug therapy (test done on the melanoma tumor) or whether you and your family members are at risk for hereditary (familial) melanoma (test done on a sample of your blood or saliva).
If your doctor suspects the cancer is advanced (has spread), specialized imaging tests are performed to provide detailed pictures of organs below your skin’s surface. A radiologist interprets the images to identify cancer spread.
Also called blood tests or draws, a small blood sample is removed to analyze for markers of disease spread. Your doctor orders a blood draw if you have a more advanced stage of melanoma or are taking drugs for melanoma that has spread to lymph nodes or other body sites. Blood tests provide a variety of information that helps doctors plan your treatment.
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Melanoma Skin Cancer
Melanoma is an aggressive type of skin cancer. Learn about skin cancer types, melanoma symptoms, and our approaches to care, including Mohs surgery.
skin cancer
cancerous moles)
skin cancer types (MSV 69
700; KD: 54)
melanoma symptoms
superficial spreading melanoma
nodular melanoma
lentigo maligna
acral lentiginous melanoma
mohs surgery