Lentigo maligna melanoma is a type of invasive skin cancer. It develops from lentigo maligna, which is sometimes called Hutchinson’s melanotic freckle. Lentigo maligna stays on the outer surface of the skin. When it starts growing beneath the skin’s surface, it becomes lentigo maligna melanoma. It’s the least common type of melanoma.
Lentigo maligna grows slowly and is usually harmless, but lentigo maligna melanoma can spread aggressively. It’s important to recognize the symptoms of lentigo maligna melanoma so you can seek treatment early on.
The visual symptoms of lentigo maligna melanoma are very similar to those of lentigo maligna. Both look like a flat or slightly raised brown patch, similar to a freckle or age spot. They have a smooth surface and an irregular shape. While they’re usually a shade of brown, they can also be pink, red, or white.
Compared to other types of skin cancer, lentigo maligna and lentigo maligna melanoma are on the larger side. They tend to be at least 6 millimeters (mm) wide and can grow to several centimeters. Most people with either condition have it on their neck or face, especially their nose and cheeks.
It can be hard to tell lentigo maligna melanoma from a freckle or age spot by looking at it. To help, you can use a trick known as the “ABCDEs” of skin cancer. If the spot is cancerous, it likely has the following symptoms:
- Asymmetry: The two halves of the spot don’t match.
- Border: The outer edges of the spot are jagged or irregular.
- Color: It includes black, red, or blue colors.
- Diameter: It’s wider than 6 mm.
- Evolving: It’s size, shape, or color is changing.
It’s also hard to visually tell the difference between lentigo maligna and lentigo maligna melanoma. Keep an eye out for these signs that may indicate lentigo maligna melanoma:
- increased thickness
- multiple colors, particularly black and blue
The exact cause of lentigo maligna melanoma is unknown, but sun exposure is the biggest risk factor for developing it. That puts people with sun-damaged skin and those who spend a lot of time outside at a higher risk. Other risk factors for developing lentigo maligna melanoma include:
- fair or light skin
- family history of skin cancer
- being male
- being over 60 years old
- having a history of noncancerous or precancerous skin spots
After reviewing your medical history and doing a physical exam, your doctor may refer you to a dermatologist or other specialist. They may use a dermatoscope, which combines a magnifying lens with a bright light, to get a better look at the spot. Your doctor may also do a biopsy. This involves removing all or a piece of the spot to see if it has cancer cells.
If the spot seems like it’s lentigo maligna melanoma, your doctor may also do a sentinel lymph node biopsy to see how far it’s spread: They first remove some nearby lymph nodes, and then have them tested for cancer. A CT scan or MRI scan can also show any signs of spreading.
If you’re diagnosed with lentigo maligna melanoma, your doctor will determine its stage, which reflects how serious it is. Breslow’s thickness, which is the thickness of the spot, helps determine the stage of skin cancer. The Clark level of invasion, which is how many skin layers are involved in the cancer, can also help determine the cancer’s stage. The stages of skin cancer range from 0 to 4, with 0 being the earliest stage.
The most common treatment for lentigo maligna melanoma is to remove the spot with surgery. Lentigo maligna melanoma is more likely to return than some other types of skin cancer, so your doctor may also remove some of the skin surrounding the spot to prevent this. If it’s spread to your lymph nodes, your doctor may choose to remove those as well.
If you have other conditions that make surgery dangerous, your doctor may recommend radiation therapy, cryosurgery, or topical imiquimod (Aldara, Zyclara). Lentigo maligna melanoma is more likely to return after nonsurgical treatment than it is after surgical treatment, so it’s important to regularly follow up with your doctor and monitor the affected area for any changes.
Untreated lentigo maligna melanoma can eventually spread throughout the body, so identifying it as early is possible is important. The more the cancer spreads, the harder it is to treat.
Surgery to remove lentigo maligna melanoma may have cosmetic complications because it usually occurs on highly visible areas such as the face. Tell your doctor if you’re worried about this. Depending on where the cancer is, they may be able to minimize the scar using a variety of surgical techniques.
The best way to prevent lentigo malignant melanoma is to limit your exposure to UV rays from the sun and tanning beds. When you do spend time in the sun, use a high-SPF sunscreen and wear a large hat that protects your face and neck.
It’s also important to monitor any changes in your skin by getting annual skin exams from your doctor or dermatologist.
Lentigo maligna melanoma is the invasive form of lentigo maligna. While lentigo maligna spreads slowly, lentigo maligna melanoma spreads aggressively. Early treatment is key to making a full recovery and lowering your chances of recurrence. Even after treatment, carefully monitor your skin for any signs of recurrence.