Lentigo Maligna Melanoma

Lentigo maligna melanoma is a type of melanoma skin cancer that primarily develops in sun-exposed areas of the body, such as the face, ears, neck and arms. In its early stages, when the cancer is confined to the top layer of skin (epidermis), the condition is known as lentigo maligna. In more advanced stages, when the cancer has grown into deeper layers of skin, the condition is known as lentigo maligna melanoma.

Unlike many other forms of skin cancer, lentigo maligna grows very slowly. Studies suggest that it can take several decades for a precancerous lesion (lentigo maligna) to progress into a cancerous tumor (lentigo maligna melanoma). Lentigo maligna melanoma is also relatively uncommon, accounting for approximately 5% of melanoma skin cancers.

What causes lentigo maligna melanoma?

Lentigo maligna melanoma results from abnormal changes to the genetic material contained in pigment-producing skin cells (melanocytes), which give the skin its color. The primary cause is chronic and cumulative exposure to harmful ultraviolet (UV) rays from the sun or indoor tanning devices, such as beds, booths and lamps.

In addition to causing sunburn and skin wrinkles, UV rays can trigger cellular DNA changes in skin cells, causing the melanocytes to grow uncontrollably and live longer than they should. The resulting excess cells may then build up, bind together and form cancerous tumors.

What are the risk factors for lentigo maligna melanoma?

Scientists have identified certain characteristics, behaviors and exposures that can increase the risk of lentigo maligna melanoma. These include:

• Frequent exposure to UV rays
• Past episodes of severe or blistering sunburn, particularly during childhood
• Fair skin that burns or freckles easily
• Naturally blonde or red hair
• Blue or green eyes
• A family history of melanoma or atypical mole syndrome
• A personal history of skin cancer
• Many unusually large or otherwise atypical moles, especially those that have irregular borders or color patterns
• More than 50 typical moles
• A suppressed immune system

Advanced age is also a risk factor for lentigo maligna melanoma, which is frequently diagnosed in adults who are older than 50 and have sun-damaged skin.

What does lentigo maligna melanoma look like?

The symptoms of lentigo maligna and lentigo maligna melanoma are primarily visible. Before transforming to a melanoma, a lentigo maligna may appear:

• Brown and uniform in color
• Smooth with the same texture as the surrounding skin
• Larger than 3 cm. in diameter

If a lentigo maligna progresses and becomes invasive, it may:

• Change in color from brown to black
• Develop a raised border
• Have a different texture than the surrounding skin

How is lentigo maligna melanoma diagnosed?

Lentigo maligna often resembles benign skin lesions, such as liver spots. Therefore, an early and accurate diagnosis is the key to achieving the best possible outcome and quality of life.

The diagnostic process for lentigo maligna melanoma may include:

• Clinical examination – A visual assessment of a suspicious skin lesion for signs of cancer, such as an irregular border, color variation and changes in size or shape
• Dermoscopy – A noninvasive examination of the cells on the surface of the skin using a handheld device with a high-powered magnifying glass and light source (dermoscope)
• Reflectance confocal microscopy (RCM) – A “virtual skin biopsy” performed with the aid of a laser light source and confocal microscope
• Excisional biopsy – Removal of the lesion for microscopic examination by a pathologist, who can identify cancerous cells

How is lentigo maligna melanoma treated?

The primary treatment for both lentigo maligna and lentigo maligna melanoma is the surgical removal of the lesion, which may be completed during a biopsy. Because many lentigo malignas develop on the head or neck, a physician may utilize special surgical techniques or tools to minimize any scarring and other cosmetic implications.

If the surgical removal of a lentigo maligna is not feasible, radiation therapy or a topical cream (imiquimod) may be considered.

Benefit from world-class care at Moffitt Cancer Center

If you would like to learn more about lentigo maligna melanoma, you can request an appointment with a specialist in Moffitt’s comprehensive Cutaneous Oncology Program by calling 1-888-663-3488 or submitting a new patient registration form online. We do not require referrals.