Melanoma



Melanoma is a type of cancer that starts in cells called melanocytes. These cells are found in the skin and produce melanin, a pigment that gives your skin its color. Melanocytes are also found in mucosal tissues, such as the lining of the mouth, nose, and rectum. Melanoma occurs when these cells grow out of control. This type of cancer can spread to other parts of the body if not treated early.

What are the symptoms of melanoma?

The most common symptom of melanoma is a new spot on the skin or a change in an existing mole.

Changes to watch for include:

  • An uneven shape or irregular borders.
  • Multiple colors or an unusual color like black, blue, or red.
  • A size larger than a pencil eraser.
  • Changes in texture, such as becoming rough, raised, or crusty.
  • Bleeding, itching, or tenderness in a mole.

Melanoma in mucosal tissues can cause different symptoms, depending on the location. For example, in the mouth, it may appear as a dark patch or lump, while in the rectum, it may cause bleeding or discomfort.

What causes melanoma?

Most cases of melanoma involving the skin are caused by DNA damage related to ultraviolet (UV) exposure from the sun or tanning beds. This damage triggers changes in the melanocytes, causing them to grow uncontrollably.

However, not all melanomas are caused by UV exposure. For example, mucosal melanomas, which occur in areas not exposed to the sun, are thought to be caused by genetic mutations unrelated to UV light. The exact reasons why these mutations occur are still being studied.

What type of cancer is melanoma?

Melanoma is a type of cancer that starts in melanocytes. It is one of the most common types of skin cancer. However, because melanocytes are also found in mucosal tissues, melanoma can occur in places like the eyes, oral cavity, and rectum. This means melanoma is not just a type of skin cancer but can also be classified as a type of eye, oral cavity, or rectal cancer.

Where is melanoma normally found?

Melanoma is most often found on parts of the body that are exposed to the sun, such as the face, arms, back, and legs. In men, melanoma is commonly found on the back. In women, it is often found on the legs. Melanoma can also develop in less exposed areas, like the palms, soles of the feet, or under the nails, especially in people with darker skin.

What does melanoma look like?

Melanoma can look different from person to person, but it often appears as an irregular mole or spot.

Doctors use the “ABCDE” rule to identify potential melanomas:

  • Asymmetry: One half of the spot does not match the other.
  • Border: The edges are uneven, scalloped, or poorly defined.
  • Color: The spot has different colors, such as black, brown, red, or white.
  • Diameter: The spot is larger than 6 millimeters (about the size of a pencil eraser).
  • Evolving: The spot changes in size, shape, or color over time.

How is this diagnosis made?

The diagnosis of melanoma is made by examining the suspicious spot and performing a biopsy. During a biopsy, a small sample of the tissue is taken and examined under a microscope by a pathologist. If melanoma is found, additional tests may be done to determine if it has spread to other parts of the body.

Types of melanoma

There are several types of melanoma, including:

  • Superficial spreading melanoma: This is the most common type. It usually grows slowly along the top layer of the skin before spreading deeper.
  • Nodular melanoma: This type grows more quickly and often appears as a raised, dark bump.
  • Lentigo maligna melanoma: This type usually occurs in older adults on sun-damaged skin, often on the face or neck.
  • Acral lentiginous melanoma: This type is less common and occurs on the palms, soles of the feet, or under the nails. It is more common in people with darker skin.
  • Mucosal melanoma: This rare type occurs in the mucous membranes of the body, such as in the mouth, nose, or rectum.
  • Ocular melanoma: This rare type affects the eye.

What are the microscopic features of melanoma?

Under the microscope, melanoma cells often look larger and more irregular than normal melanocytes. They may have uneven shapes and unusually large nuclei (the center of the cell). Pathologists look for certain patterns, such as cells spreading into deeper layers of the skin or forming clusters. Special stains or tests, like immunohistochemistry, may be used to confirm the diagnosis.

Learn more about your pathology report for melanoma

Invasive melanoma of the skin
Lentigo maligna
Lentigo maligna melanoma
Melanoma in situ of the skin
Mucosal melanoma of the head and neck
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