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Lentigo maligna

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Lentigo maligna

Also known as Hutchinson’s melanotic freckle

What is lentigo maligna?

Lentigo maligna is an early form of melanoma. In lentigo maligna the cancer cells are confined to the upper layer of the skin (epidermis). When the cancer cells spread deeper into the skin (to dermis) it is called lentigo maligna melanoma. Lentigo maligna occurs most commonly in sun damaged areas such as the face and neck in fair skinned people over the age of 60. The lesion grows slowly in size over a number of years. Melanoma is a potentially lethal disease and lentigo maligna should be diagnosed and excised as soon as possible.

What causes lentigo maligna?

The cause of lentigo maligna is sun exposure or solarium use.

Factors that predispose a person to developing lentigo maligna or associated condition include:

  • chronic sun damaged/solar-induced skin damage
  • fair skin complexion
  • male gender
  • a personal history of non melanoma skin cancer and precancerous lesions
  • older individuals (those between 60 to 80 years are most commonly affected)

What does lentigo maligna look like?

Lentigo maligna commonly looks like a freckle, age spot, sun spot or brown patch that slowly changes shape and grows in size.  The spot may be large in size, irregularly shaped with a smooth surface, and of multiple shades of brown and sometimes other colours.

Thickening of part of the lesion, increasing number of colours, ulceration or bleeding can be markers that the lesion is changing into a lentigo maligna melanoma.

How is lentigo maligna diagnosed?

Lentigo maligna is diagnosed clinically by a dermatologist, sometimes with the help of a dermatoscope (a tool used to magnify and look closely at skin moles). The lesion may be difficult to distinguish from a benign, non-cancerous lesion.  If the lesion is suspect, the doctor will biopsy or remove it to confirm the diagnosis.

How is lentigo maligna treated?

There are a few ways of treating lentigo maligna including:

  • Surgical excision

Lentigo maligna is usually removed by surgical excision with an appropriate margin around the lesion for the best outcome. More specialised surgery or other investigations may be needed in some cases.

  • Non-surgical removal

In cases where surgical excision cannot be performed (lesion is too large, surgery will be too deforming or contraindicated), other treatment methods include radiotherapy, cryotherapy and imiquimod cream.  Then close monitoring of the lesion is required.

What is the likely outcome of lentigo maligna?

Lentigo maligna has a good prognosis when detected early and treated appropriately.  However, a small percentage of lesions may be undetected and progress to become an invasive melanoma which is potentially life-threatening.

Regular follow-up and full skin examinations are need with the treating doctor to review past treatment sites and monitor areas of suspicion.

This information has been written by Dr Shelley Ji Eun Hwang, Dr Andrew Moss & A/Professor Pablo Fernandez-Penas
Updated 23 June 2015