What Is Lentigo Maligna Melanoma Causes Treatment?

Lentigo maligna melanoma is a type of skin cancer that begins in melanocytes, the cells that produce pigment. It starts as a slow-growing, flat, brown or dark patch on skin that has had years of sun exposure, most often on the face. Lentigo maligna is the early, non-invasive stage, and it becomes lentigo maligna melanoma when the abnormal cells grow deeper into the skin. Early treatment is highly effective, but the condition can be missed because it looks like a harmless age spot.

What Is Lentigo Maligna Melanoma Causes Treatment?

Lentigo maligna melanoma is a form of melanoma that develops from a precancerous patch called lentigo maligna. The cause is cumulative sun damage over many years. Treatment involves surgically removing the entire lesion, with the specific method depending on the size, location, and depth of the growth. When caught in the early, flat stage, the cure rate is very high.

How Does Lentigo Maligna Differ From Lentigo Maligna Melanoma?

The difference is about depth, not appearance. Lentigo maligna stays in the top layer of skin, the epidermis. It has not yet invaded deeper layers. Lentigo maligna melanoma means the cancer cells have broken through into the dermis, the second layer of skin.

This distinction matters for prognosis. When the cancer is still confined to the epidermis, it cannot spread to lymph nodes or other organs because there are no blood vessels in that top layer. Once it invades the dermis, it gains access to blood and lymphatic vessels and can metastasize.

Both stages look similar on the surface. A dermatologist cannot tell the difference by looking alone. A biopsy that includes the full depth of the lesion is required to determine the stage.

Who Gets Lentigo Maligna Melanoma?

This type of melanoma is strongly linked to long-term sun exposure. It is most common in people over age 50, and the average age at diagnosis is in the mid-60s. Fair-skinned people who burn easily are at highest risk.

The most common location is the face, particularly the cheeks, nose, and forehead. It can also appear on the ears, scalp, neck, and forearms. These are areas that receive decades of sun exposure even in people who do not intentionally tan.

Men and women are affected at similar rates, though men more often develop it on the ears and scalp. Women more often develop it on the cheeks and nose. A history of sunburns, especially in youth, increases risk, but this cancer is more about total lifetime exposure than individual burns.

What Does Lentigo Maligna Look Like?

Lentigo maligna appears as a flat or slightly raised patch with irregular borders. The color can vary from light brown to dark brown to black, and it often has multiple shades within the same lesion. It grows slowly over years, sometimes a decade or more.

Many people mistake it for a sun spot or age spot. The key differences are asymmetry, irregular borders, and color variation. A common warning sign is a spot that continues to enlarge or darken over time.

Dermatologists use the ABCDE rule to screen for melanoma, but lentigo maligna often violates these criteria. It may be symmetrical, have regular borders, and remain smaller than 6 millimeters for years. The most reliable warning sign is a pigmented lesion on sun-damaged skin that is changing.

If a spot on your face or other sun-exposed area has been growing slowly for months or years, it deserves a professional evaluation.

How Is Lentigo Maligna Melanoma Diagnosed?

Diagnosis requires a biopsy. The dermatologist will numb the area and remove either the entire lesion or a representative sample. A pathologist examines the tissue under a microscope to determine whether abnormal melanocytes are present and whether they have invaded the dermis.

Dermoscopy, a technique using a special magnifying lens, helps dermatologists identify suspicious features before biopsy. It improves diagnostic accuracy but does not replace biopsy.

If the biopsy shows invasive melanoma, the depth of invasion is measured in millimeters. This measurement, called Breslow thickness, is the single most important factor in determining prognosis and treatment planning.

For lentigo maligna that is not invasive, the biopsy confirms the diagnosis and guides surgical planning. No additional imaging or blood tests are needed for the non-invasive stage.

What Are the Treatment Options?

Surgery is the standard treatment. The goal is to remove the entire lesion with a margin of normal skin around it. This ensures no microscopic cancer cells remain.

Two surgical approaches are commonly used:

• Standard excision — The surgeon removes the lesion with a predetermined margin of normal skin, typically 5 to 10 millimeters, then closes the wound with stitches.
• Mohs micrographic surgery — The surgeon removes the visible lesion plus a thin layer of tissue, examines it under a microscope immediately, and repeats this process until no cancer cells remain. This approach preserves the most healthy tissue, which matters on the face.

Mohs surgery is often preferred for lentigo maligna on the face because it offers the highest cure rate while sparing healthy skin. However, it requires specialized training and is not available everywhere.

For people who cannot have surgery, or for those with very large lesions, radiation therapy is an alternative. It is effective but has a higher recurrence rate than surgery. Topical treatments like imiquimod cream are sometimes used, but they are considered less reliable than surgery and are not a standard first-line treatment.

After treatment, regular skin checks are essential. Lentigo maligna can recur even after successful treatment, sometimes years later. People who have had one skin cancer are at higher risk of developing another.

What Is the Prognosis?

The prognosis for lentigo maligna is excellent. It is a slow-growing cancer, and the non-invasive stage carries a cure rate above 95 percent with appropriate surgical removal.

Once it becomes invasive, the prognosis depends on the Breslow thickness. Thin melanomas, less than 1 millimeter deep, have a very high cure rate. Thicker melanomas carry a higher risk of spread and require more extensive treatment, including possibly sentinel lymph node biopsy and immunotherapy.

Because lentigo maligna grows slowly over years, there is usually a wide window for early detection. Most people have ample time to seek treatment before the cancer becomes invasive. The danger is not the speed of the cancer but the tendency to dismiss it as a harmless age spot.

How Can You Prevent Lentigo Maligna Melanoma?

Prevention focuses on reducing cumulative sun damage. Daily sunscreen use on exposed skin, especially the face, is the most important step. Sunscreen with SPF 30 or higher, applied every morning and reapplied every two hours when outdoors, provides meaningful protection.

Protective clothing, wide-brimmed hats, and seeking shade during peak sun hours from 10 a.m. to 4 p.m. all reduce exposure. Avoiding indoor tanning beds is essential, as they deliver concentrated UV radiation that damages skin.

Regular self-examinations help with early detection. Look at your face in a mirror, checking for any pigmented spot that is changing, growing, or developing irregular features. Ask a partner or friend to check your scalp and ears, areas you cannot easily see.

Annual skin examinations by a dermatologist are recommended for people with a history of significant sun exposure, a personal history of skin cancer, or a family history of melanoma. People with many moles or a history of sunburns may benefit from more frequent checks.

When Should You See a Doctor?

See a dermatologist if you notice any pigmented spot on sun-exposed skin that is growing, changing color, or developing irregular borders. A spot that has been present for years but recently changed deserves attention.

There is no harm in having a spot checked. The vast majority of biopsied lesions are benign. But the small percentage that are cancerous are far easier to treat when caught early.

Do not wait for a spot to become painful, itchy, or bleed. Lentigo maligna often causes no symptoms at all until it reaches an advanced stage. The absence of symptoms does not mean the spot is harmless.