Skin Cancer

Melanoma (MM)

Overview

Name

Melanoma (MM)

Type

Skin Cancer

Melanoma is sometimes referred to as “malignant melanoma.” However, this term is redundant since melanomas are a malignant form of skin cancer. More than one million Americans are either melanoma survivors or are currently being treated for melanoma, and it is estimated that as many as 192,000 new cases will be diagnosed in 2019. In around half of the cases, the cancer is caught early, and is limited to the upper layer of skin (epidermis). Many of the remaining cases involve invasion of cancer cells to the deeper layer of skin (dermis), or to tissue below the skin. Melanoma is an aggressive cancer and can spread (metastasize) to other areas of the body, resulting in over 7,000 deaths annually. However, caught early, melanoma is highly treatable. In older adults, the incidence in males is at least twice that of females. However, in adults less than the age of 50 years, more cases are diagnosed in women. It is less common in individuals who are darkly pigmented, but importantly, may be more deadly when it does occur. Melanoma is diagnosed more frequently in older adults, but individuals of all ages can be affected, including teens, children and even infants. In fact, melanoma is the most common cancer in young adults aged 25 to 29 years and the second most common cancer in those aged 15 to 29 years.

 

The cancer cells in melanoma are derived from melanocytes, the pigment-producing cells in the skin. When melanocytes become damaged from UV exposure or from other factors, the cells start to divide in an unregulated manner and the production of pigment (melanin) can become erratic. The colors observed in melanomas can range from tan, brown, black, gray, rust, pink, purple, and white, as well as other colors. Some melanomas will have a solitary color such as black or dark brown, while others will appear multi-colored. Rarely, melanomas will be predominately white to pinkish in an “albino-like” variant; these are referred to as amelanotic melanomas (e.g., no melanin). Melanomas that develop under fingernails and toenails may appear as a dark streak under the nail, or as a darkened area in the cuticle or nail bed.

 

Although the causes of melanoma are not completely understood, certain risk factors are known to increase the likelihood of developing melanoma:

– Exposure to UV, or to tanning parlors, sunlamps and other UV-producing devices

– Living in sunny areas, or near the equator

– A history of blistering sunburns during childhood

– Fair skin, especially skin that easily burns or that rarely if ever tans

– Light eyes (blue, gray or green)

– Light color hair (naturally blond or red)

– Presence of many moles on the skin, especially large or unusual moles

– Personal or family history of melanoma

– Testing positive for a hereditary melanoma gene

– History of other cancers, especially breast

– History of immunosuppression (caused by diseases such as HIV, or by treatment for certain medical conditions such as organ transplants)

 

Melanomas can occur on any part of the skin, including the head, face, scalp, neck, trunk, arms and legs, backs and fronts of hands and feet, between fingers and toes, and even under fingernails and toenails. “Subungual” melanomas, which develop under the nails, are not caused from crush injuries; blood accumulated from trauma gradually moves closer to the tip of the nail over time, whereas the pigment in subungual melanomas tends to remain in the same location. Melanomas which develop on the palms of the hands or on the soles of the feet are referred to as “acral” melanomas; these seem to be more common in people with darker complexions. Melanoma can develop within an existing mole or skin growth or arise as a new growth on previously normal-appearing skin. Congenital moles (e.g., moles which have been present since birth, infancy or early childhood) are at higher risk for subsequent transition into a melanoma. Moreover, melanomas can develop on “wet” areas of skin, such as the mucosa of the mouth and oral cavity, within the nasal cavity, inside of the eye, on the genitalia and anus, and in internal organs. Many melanomas start as flat pigmented lesions, but as the cancer advances, raised bumps may appear within the melanoma. Sometimes this is referred to as “fried egg-like.” Occasionally, melanomas start as raised, nipple-like bumps which become progressively larger over time.

 

The DNA damage in melanomas causes the cancer cells to grow and behave in an unorganized and abnormal manner, which accounts for the many shapes, sizes and colors that typify melanomas. An easy way of describing melanomas has been the development of the ABCDE warning signs:

 

A: Asymmetry—The shape of a melanoma tends to be asymmetrical, meaning that if a melanoma were divided in half, either vertically or horizontally, the two sides would not match up or be the same shape.

 

B: Border—There may be curves and bulges on the outer margins of the cancer, often (but not always) resulting in a wavy or scalloped border edge. Some of the bulges may be quite pronounced, appearing as oddly-shaped extensions of the tumor into the surrounding skin. This may be attributed to some areas of cells growing faster than other areas, causing pushed-out sections on the border. The border may also appear somewhat smudged, in contrast to the sharp borders observed in normal moles.

 

C: Color—Often, melanomas present with multiple colors, and some of these colors may differ considerably from the colors normally seen on one’s skin; for example, a new dark brown, gray or black growth on a person whose other skin growths (such as normal moles) are light brown or tan. In melanomas with multiple colors, the pattern of color may appear quite disorganized, with some areas appearing much darker or lighter than surrounding areas. Again, the DNA damage in melanomas often affects pigment production, causing some cells to make more pigment or different colored pigment compared to neighboring cells. However, as described above, some melanomas are uniformly pigmented (one color), or may show an absence of color (amelanotic melanomas). In some melanomas that are raised, the pigment may appear to spill over onto the adjacent skin.

 

D: Diameter—Most normal moles are smaller than the eraser on the end of a pencil (about 5-6 millimeters). In contrast, melanomas can be much larger and can exceed the size of a quarter.

 

E: Evolving—Melanomas tend to change in size, shape and color over time, and become progressively different in appearance from other growths present on the skin.

 

Melanomas may meet some or all of the ABCDE warning signs. Any new growths on the skin that bleed, itch, change in appearance, fail to heal or meet any of the ABCDE warning signs should be checked by a dermatologist.

 

All photographs and diagrams are intended for informational purposes only and are not intended to be used for diagnosis.  A dermatologist should be consulted for examination and diagnosis of skin lesions.

Images

A diagram of the skin epidermis. The octopus-like brown cell in the basal cell layer (bottom layer in the diagram) is a normal melanocyte. When melanocytes become cancerous, they give rise to melanoma.
A diagram of the skin epidermis. The octopus-like brown cell in the basal cell layer (bottom layer in the diagram) is a normal melanocyte. When melanocytes become cancerous, they give rise to melanoma.
Superficial spreading melanoma. The MM on this patient met all the ABCDE characteristics (see grid). The colors include white, pink, purple, tan, and dark brown/black. It is about 4 cm in size (roughly 1.5 inches). The borders are irregular, and the shape of the MM is not symmetrical. For comparison, two normal moles (arrows) can be seen just to the upper right and left of the MM.
Superficial spreading melanoma. The MM on this patient met all the ABCDE characteristics (see grid). The colors include white, pink, purple, tan, and dark brown/black. It is about 4 cm in size (roughly 1.5 inches). The borders are irregular, and the shape of the MM is not symmetrical. For comparison, two normal moles (arrows) can be seen just to the upper right and left of the MM.
A superficial spreading MM with pronounced variation in color. (Photo courtesy of the National Cancer Institute, nci-vol-9189-72)
A superficial spreading MM with pronounced variation in color. (Photo courtesy of the National Cancer Institute, nci-vol-9189-72)
Superficial spreading MM demonstrating pigmentation which is predominantly black. (Photo courtesy of the National Cancer Institute, nci-vol-2364-72)
Superficial spreading MM demonstrating pigmentation which is predominantly black. (Photo courtesy of the National Cancer Institute, nci-vol-2364-72)
Use the grid to evaluate the ABCD of this MM. (Photo courtesy of the National Cancer Institute, nci-vol-9186-72)
Use the grid to evaluate the ABCD of this MM. (Photo courtesy of the National Cancer Institute, nci-vol-9186-72)
This MM resembles a “fried egg.” The melanoma that first appeared was flat (right side of the MM); this is called the horizontal phase of growth. As the MM became larger, it developed a raised nodule or bump (left side of the MM); this is called the vertical phase of growth.
This MM resembles a “fried egg.” The melanoma that first appeared was flat (right side of the MM); this is called the horizontal phase of growth. As the MM became larger, it developed a raised nodule or bump (left side of the MM); this is called the vertical phase of growth.
Another example of a MM with both flat (horizontal) and raised (vertical) components of growth. In this case, the raised nodule on the right side of the tumor appears to be red without any of the pigment melanin which characterizes most melanomas. (Photo courtesy of the National Cancer Institute, nci-vol-9182-72)
Another example of a MM with both flat (horizontal) and raised (vertical) components of growth. In this case, the raised nodule on the right side of the tumor appears to be red without any of the pigment melanin which characterizes most melanomas. (Photo courtesy of the National Cancer Institute, nci-vol-9182-72)
A nodular melanoma. This aggressive form of MM arises as a nodule or bump without any evidence of the slower growing flat (horizontal) phase of growth.
A nodular melanoma. This aggressive form of MM arises as a nodule or bump without any evidence of the slower growing flat (horizontal) phase of growth.
This is an example of an acral melanoma which has developed on the sole of the foot. This type of MM can also develop on the palm of the hand or between fingers or toes. They tend to be more common in individuals with darker pigmentation. (Photo courtesy of Kelly Nelson, MD and the National Cancer Institute, nci-vol-9246-72)
This is an example of an acral melanoma which has developed on the sole of the foot. This type of MM can also develop on the palm of the hand or between fingers or toes. They tend to be more common in individuals with darker pigmentation. (Photo courtesy of Kelly Nelson, MD and the National Cancer Institute, nci-vol-9246-72)
This is an early and very small subungual MM (occurring underneath a fingernail or toenail). Note that the pigment in this lesion is not only under the fingernail, it also affects the cuticle. (Photo courtesy of Drs. John Brad Turner and Brian Rinker, Healthcare (Basel). 2014 Mar; 2(1): 125–138; Melanoma of the Hand: Current Practice and New Frontiers)
This is an early and very small subungual MM (occurring underneath a fingernail or toenail). Note that the pigment in this lesion is not only under the fingernail, it also affects the cuticle. (Photo courtesy of Drs. John Brad Turner and Brian Rinker, Healthcare (Basel). 2014 Mar; 2(1): 125–138; Melanoma of the Hand: Current Practice and New Frontiers)
Melanoma is a type of skin cancer which can invade other parts of the body in a process called metastasis. Each of the reddish or black nodules in this photo represents a nest of melanoma cells which has spread (metastasized) from the original tumor to other parts of the skin. (Photo courtesy of the National Cancer Institute, nci-vol-9290-72) Normal moles are benign (not cancerous) pigmented lesions which are commonly seen on both children and adults. For comparison, please refer to the section on Normal Moles.
Melanoma is a type of skin cancer which can invade other parts of the body in a process called metastasis. Each of the reddish or black nodules in this photo represents a nest of melanoma cells which has spread (metastasized) from the original tumor to other parts of the skin. (Photo courtesy of the National Cancer Institute, nci-vol-9290-72) Normal moles are benign (not cancerous) pigmented lesions which are commonly seen on both children and adults. For comparison, please refer to the section on Normal Moles.
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