Lentigo maligna is a slow growing form of superficial melanoma and can remain unchanged for some time, it’s important to have it checked out. Early detection and treatment can help prevent it from becoming an invasive cancer that is more likely to spread to distant sites.
Here’s a look at the symptoms and risk factors for lentigo maligna. Plus, find out where on the body you’re most likely to spot it.
Lentigo maligna melanoma is a type of melanoma that has advanced from a lentigo maligna. Lentigo maligna is an early form of melanoma. This slow-growing skin cancer can remain precancerous for many years. It may be referred to as an ‘in situ melanoma’. This is where the cancer cells stay in the top layer of the skin (the epidermis). They haven’t spread deeper into the skin or invaded other parts of the body.
Lentigo maligna melanoma accounts for between 5-15 per cent of melanomas. It’s most often found on areas of the body that get a large amount of sun exposure, such as the face, ears, and neck. This type of skin cancer is common in people over the age of 60 with sun-damaged skin.
Typically, lentigo maligna looks like a flat patch of discoloured skin. It can be brown or brown/pink and the colour may change over time. Initially, it may look like a freckle or sunspot.
Characteristics of early stage lentigo maligna include:
Lentigo maligna melanoma symptoms include:
Lentigo maligna melanoma is caused by the uncontrolled reproduction of pigment cells (melanocytes) in the basal layer of the epidermis. What triggers the rapid reproduction of cells is unknown. Yet, UV radiation (from the sun or sunbeds) is a significant risk factor.
When UV light enters the skin, it can damage the cells’ DNA. As a result, the cells grow rapidly and divide. This can produce tumours or lesions that may be cancerous (malignant) or harmless (benign). People with existing sun damage or who spent a lot of time outdoors are at higher risk of lentigo maligna melanoma.
Other risk factors include:
Accurate diagnosis of lentigo maligna and lentigo maligna melanoma is essential. Particularly as both types of melanoma have features that are similar to benign lesions, such as sunspots (solar lentigo).
Initially, a dermatoscope may be used to examine the skin under magnification. If lentigo maligna is suspected, a sample of the tissue will be removed. This is called a partial biopsy and is used to confirm the diagnosis. In some instances, the entire lesion may be removed.
In the case of invasive lentigo maligna melanoma, where the cancer may have spread deeper into the skin, other tests may be carried out. A sentinel lymph node biopsy can see how far the melanoma has spread. This involves removing part of the nearby lymph nodes for testing.
As part of the diagnosis, your doctor or dermatologist will advise at which stage the cancer is at. Like other skin cancers, lentigo maligna melanoma stages range from stage 0 - 4. Stage 0 is the earliest stage (this includes melanoma in situ lentigo maligna).
For invasive lentigo maligna melanoma, the Breslow thickness will be reported. This refers to the depth of the tumour and may help predict the outcome. The Clark level of invasion refers to how many layers of skin are involved. This can help predict the risk of metastasis (spread of cancer cells to other parts of the body).
The most common treatment for lentigo maligna melanoma is surgery. A wide local excision involves removing the lesion along with a margin of healthy skin. This helps to ensure all the cancerous cells have been removed. However, removing a wide margin can be difficult, as the face and neck offers a relatively small area of skin.
Other treatments that may be considered include:
High-frequency x-rays destroy the cancerous cells. This may require multiple 30-minute sessions over 4-5 weeks.
Imiquimod is a topical cream that works with the body’s immune system to target and destroy the cancerous cells.
Extreme cold, such as liquid nitrogen, is used to destroy abnormal tissue.
The survival rates for lentigo maligna melanoma are very good, especially in cases where the cancer is detected and treated early. According to a 2016 study, published in BMC Cancer, the survival rates are:
The best way to prevent lentigo maligna melanoma is to practise sun safety.
Regular skin checks are important for monitoring any changes to your skin. Although lentigo maligna melanoma is quite rare and slow growing, it can recur. Even after treatment, it’s essential to continue to monitor your skin for signs of recurrence.
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