Lentigo maligna melanoma is an uncommon form of skin cancer typically affecting older individuals. It develops from lentigo maligna, also known as Hutchinson’s melanotic freckle.

This cancer typically starts on the surface of the skin on parts of the body that get exposed to too much sun, which tend to include the face, forearms, and neck. When the cancer goes beneath the surface of the skin, it becomes lentigo maligna melanoma.

Lentigo maligna melanoma is an aggressive form of cancer that is faster growing than lentigo maligna and may spread to other areas of the body.

In this article, we look at the signs and symptoms of lentigo maligna melanoma, as well as the causes and risk factors. We also discuss its diagnosis and the available treatment options.

Lentigo maligna melanoma typically presents as a dark mole that changes in shape, color, or size.

Initially, it tends to appear as an irregular brown macule or lesion on the head or neck. As it progresses, it can become one of several different colors, including black.

It is typically irregular and will grow slowly, often starting its expansion in a radial pattern. In time, it will usually begin to elongate.

The most common risk factors for lentigo maligna melanoma include:

  • chronic exposure to sunlight, which causes skin damage
  • a history of sunburns
  • lighter skin
  • the tendency to form harmless patches of darkened skin, known as solar lentigines
  • a history of nonmelanoma skin cancers
  • certain genetic mutations, most commonly P53 mutations

A person should see a doctor if they are concerned about a new mole that has appeared on their face, neck, or forearms.

If a person notices that an existing mole has changed in shape, color, or size, they should seek medical advice.

In many cases, a doctor will refer a person to a specialist for further analysis.

A doctor will often refer a person to a dermatologist for a diagnosis.

A dermatologist can better distinguish between a benign skin growth, such as a mole, and more serious conditions.

This specialist will typically ask the person about their symptoms and what they have observed over time. They will also examine the skin, including the area of skin about which the person is concerned.

In some cases, a dermatologist can make a preliminary diagnosis based on a physical examination. They may recommend the removal of some of the potentially affected area of skin as a precaution before testing for lentigo maligna melanoma.

In other cases, a dermatologist may do a biopsy and take a small sample of the suspected cancer to send to a lab. Here, technicians will analyze it to determine whether cancer is present.

If a person has lentigo maligna melanoma, a doctor will assess the appropriate treatment options. These will vary depending on the stage of the cancer and how far it has spread.

The goals of treatment include:

  • curing the cancer
  • preventing recurrence of the cancer
  • preserving the appearance of the skin

The usual treatment involves the removal of the growth. A surgeon will remove the affected area of skin and an additional 5 millimeters of the healthy surrounding skin.

Sometimes, the growth is on an area of the body where it would be difficult to remove. In these cases, a doctor may choose a different treatment option, such as:

With sufficiently early diagnosis and treatment, lentigo maligna and lentigo maligna melanoma are both curable forms of skin cancer.

The key to treatment is catching the cancer as early as possible and preventing it from spreading to other areas of the body. In these situations, a person’s outlook is generally positive.

Practicing safety in the sun helps prevent lentigo maligna melanoma from occurring.

Some practical tips for preventing sun damage include:

  • avoiding spending prolonged periods in the sun
  • wearing a hat and protective gear to avoid sun exposure
  • wearing and regularly reapplying sunblock that is SPF 15 or higher
  • taking care to avoid sunburns
  • refraining from using tanning beds

Lentigo maligna melanoma is an invasive form of skin cancer, but it is treatable if a doctor or dermatologist diagnoses it early. A person should, therefore, take any early signs or symptoms seriously and seek medical advice.

In its early form, lentigo maligna, the cancer has not yet spread. When a doctor diagnoses lentigo maligna melanoma, this means that the cancer has spread from the skin to other tissue in the body.