Cutaneous Melanoma, or Melanoma of the Skin
Melanoma that occurs on the skin, called cutaneous melanoma, is the most common type of melanoma. This type of melanoma occurs in all parts of the skin, including the soles of feet, on the palms of the hand, in between toes and fingers, and underneath the finger and toe nails.
Cutaneous melanoma can be described in the following ways:
Superficial Spreading Melanoma
Superficial Spreading Melanoma (SSM) accounts for approximately 70% of all diagnosed melanomas. It usually occurs in a previously benign (non-cancerous) mole and is most commonly found on the trunk and back in men and on the legs and back in women.
What does Superficial Spreading Melanoma look like?
Known as a dysplastic nevus, in early stages SSM may look like a freckle that is spreading sideways on the skin. Over time the pigmentation could darken or lighten, the area may itch, or the lesion could grow and develop increasingly irregular borders.
SSM can progress rapidly, so if you see a lesion or mole that you suspect could be melanoma, have it checked out by a dermatologist immediately. Check out our pictures of melanoma for additional examples.
The 4-by-8-mm, pink-tan lesion with irregular borders at the upper left (arrow) is a dysplastic nevus. Arising from it is an invasive malignant melanoma, with its characteristic blue-black color, notched border, and distorted surface. The gray area at the lower left represents tumor regression.
|This large (7 by 11 mm) macular lesion displays an irregular, scalloped border, which is indistinct in some areas. In addition to hues of tan and brown, several pink areas (arrows) are present. The presence of pink colors in the macular portion of a melanocytic nevus is quite distinctive for dysplastic nevi.|
Source: National Cancer Institute
|The delicate, hazy, tan macular rim of this lesion, although not clinically dramatic, represents persistent melanocytic proliferation beyond the lateral limits of the common mole at its center.|
Nodular melanoma accounts for approximately 15% of all diagnosed melanomas. Unfortunately, it is the most aggressive type of melanoma. It is more common in males and can occur at any age but is most often seen in individuals aged 60 and older. Check out our pictures of melanoma for additional examples.
What does nodular melanoma look like?
Nodular melanoma may appear where a mole or lesion did not exist before. It tends to spread more rapidly in depth, making it more difficult to visibly see the progression. Lesions are usually darkly pigmented but can also be light brown or colorless.
Acral Lentiginous Melanoma (ALM)
Although acral lentiginous melanoma only accounts for about 5% of all diagnosed melanomas, it makes up about 50% of diagnosed melanomas in Asians and individuals with dark skin. These melanomas can develop anywhere on the body, including the palms of the hands, the soles of the feet or underneath the fingernails and toenails.
Subungual melanoma is a rare sub-type of ALM. Most subungual melanomas involve the thumb nail or the nail of the great toe. If you have a dark spot under your fingernail or toenail that appears, be sure to bring it to the attention of your dermatologist - especially if there has not been any recent trauma to the area (sometimes a bruise caused by trauma to the fingernail or toenail can look similar to a melanoma).
What does acral lentiginous melanoma (ALM) look like?
ALM is often overlooked or mistaken, because it tends to appear like a dark spot, bruise or streak under the fingernail (sometimes called subungual melanoma) or toenail in its early stages. On the palm or sole of the foot, ALM can look like a bruise or an irregular tan, brown or black spot. Under the nail, ALM can appear as a dark spot or stripe and is found most often on the thumb or the big toe.
ALM can also develop on the mucous membranes inside the nose or mouth, and early indicators are usually a stuffy nose, nose bleeds or a darkened mass inside the mouth.
Reggae musician Bob Marley died in 1981 of complications from acral lentiginous melanoma, which originated under his toenail and metastasized to other parts of his body.
Source: First two photos courtesy of Dr. Guowen Wang in the Department of Soft Tissue Cancer, Tianjin Cancer Center, Tianjin Medical University; Third photo courtesy of a pediatric acral melanoma patient;
Lentigo Maligna Melanoma
Lentigo Maligna Melanoma (LMM) accounts for approximately 10% of all diagnosed melanomas. It often occurs on the face of middle-aged to elderly individuals who have experienced sun damage.
What does lentigo maligna melanoma look like?
Lentigo Maligna Melanoma is sometimes mistaken as sun spots and goes undetected, making it very dangerous.
As these lesions spread in width and in depth it will typically have a very irregular border and vary in shades of brown or black. Sometimes dark nodules will appear within the brown or black area and will feel like small bumps. Check out our pictures of melanoma for additional examples.
Desmoplastic melanoma (DM) is a rare subtype of cutaneous melanoma in which the melanoma cells are surrounded by fibrous tissue. DM most commonly develops on the sun-exposed areas of the head and neck. The majority of people diagnosed with DM are older-age males with chronic UV exposure and sun-damaged skin.
About half of DMs develop in association with a lentigo maligna melanoma. They are often difficult to diagnose and, therefore, tend to be quite invasive (deep) at the time of diagnosis. Although DM is associated with a higher tendency for local recurrence, regional lymph node involvement is less common.
Genetic Mutations in Melanoma
Mutations in certain proteins are allowing scientists to further define the melanoma at the molecular level. The BRAF mutation is the most common type of genetic mutation in cutaneous melanoma, appearing in approximately 50% of melanoma cases. The NRAS mutation is also commonly found in cutaneous melanoma, occurring in approximately 20% of cases. The most common mutation in mucosal melanoma is found in a protein called KIT. The KIT mutation is also common in acral melanoma. The most common mutations currently described in ocular melanoma are the GNAQ and GNA11 genes. All melanoma patients should have their melanoma tested for genetic mutations so the proper treatment options can be discussed.