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Melanoma

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Precancerous conditions of the skin

Precancerous conditions of the skin have the potential to develop into melanoma.

Atypical moles

An atypical mole (also called dysplastic nevus) is an unusual mole that looks different from an ordinary mole. Atypical moles are more likely than ordinary moles to develop into melanoma. Atypical moles are most commonly found on the back, chest, buttocks, breasts and scalp. They can be found on sun-exposed and non-exposed skin sites.

Risk factors

The following risk factor may increase a person’s chance of developing atypical moles:

  • familial dysplastic nevus syndrome

Signs and symptoms

The signs and symptoms of an atypical mole may include:

  • multiple shades of brown or red-brown in colour
  • size is greater than 6 mm across
  • irregular shape
  • pebbly or centrally raised surface
  • irregular border

Diagnosis

If the signs and symptoms of an atypical mole are present, or if the doctor suspects an atypical mole, tests will be done to make a diagnosis. Tests may include:

  • biopsy

Treatment

Treatment options for atypical moles may include:

  • surgical excision

Congenital melanocytic nevi

Congenital melanocytic nevi are birthmarks or large moles that are present at birth or may develop during early childhood. There may be one or more present. People who are born with a congenital nevus or who develop one during early childhood have an increased risk of developing melanoma.

Risk factors

There are no known risk factors for developing congenital melanocytic nevi. However, researchers have suggested that a cell mutation may be a cause.

Signs and symptoms

The signs and symptoms of congenital melanocytic nevi may include:

  • brown or black, even or speckled colouring
  • raised appearance
  • presence of coarse, dark hair
  • irregular surface
  • regular or irregular borders

Diagnosis

If the signs and symptoms of a congenital melanocytic nevi are present, or if the doctor suspects a congenital melanocytic nevi, tests will be done to make a diagnosis. Tests may include:

  • skin examination
  • biopsy

Treatment

Treatment options for congenital melanocytic nevi depend on the size and location of the nevus, its potential to become cancerous and the person’s age.

For a small (less than 1.5 cm) or medium (between 1.5 and 20 cm) congenital nevus, treatment may include:

  • observation with baseline photography and regular follow-up
  • surgical excision for cosmetic reasons

For large (greater than 20 cm) congenital nevus, treatment may include:

  • surgical excision
    • This is usually done as soon as possible because there is a high risk that it will become cancerous.
    • Often, complete excision may take several surgeries.
  • follow-up every 6–12 months

For lesions that are too large to be removed by surgery, treatment may include:

  • yearly examination
  • photographs to help monitor any changes when checking your skin

Lentigo maligna

Lentigo maligna is a precancerous condition that may lead to lentigo maligna melanoma. Lentigo maligna is a spreading brown patch, often with considerable variation in colour. It is usually flat. It can slowly get bigger over years. Lentigo maligna is most commonly found on chronically sun-exposed areas, such as the face, neck, back of hands and lower legs.

Lentigo maligna can be confused with a benign condition called lentigo simplex. Lentigo simplex lesions are brown patches that develop on the face of elderly people from skin damage.

Risk factors

The following risk factor may increase a person’s chance of developing lentigo maligna:

  • sun exposure

Signs and symptoms

The signs and symptoms of lentigo maligna may include:

  • brown patch or tan patch with large variation in colour
  • large size
  • mottling or freckling
  • usually a flat patch, but may become elevated

Diagnosis

If the signs and symptoms of lentigo maligna are present, or if the doctor suspects lentigo maligna, tests will be done to make a diagnosis. Tests may include:

Treatment

Treatment options for lentigo maligna may include:

  • surgical excision
  • radiation therapy
  • topical chemotherapy with imiquimod (Aldara)

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