Lentigo Maligna Melanoma

What is Lentigo Maligna Melanoma?

Lentigo maligna (LM) is a specific type of skin cancer known as melanoma. It often appears as an odd-shaped brown spot on sun-damaged skin, especially in areas like the head and neck of older people. It was initially noticed and described by a doctor named Hutchinson in 1890, who called it “Hutchinson’s melanotic freckle.”

For a long time in the early 1900s, LM was considered either harmless, infectious, or a precursor to cancer due to its slow-growing nature. It had different names like “junctional nevus,” “infective senile freckles,” and “circumscribed precancerous melanosis.” But it wasn’t until the 1970s and 80s when studies conducted by Silvers, Ackerman and their colleagues made it clear that LM is actually cancerous.

Today, LM is identified as melanoma at its earliest stage (referred to as melanoma in situ or MIS) which affects long-term sun-damaged skin. This means that the cancer is only present in the uppermost layer of the skin, known as the epidermis. If LM starts to invade deeper layers of skin, it is then termed lentigo maligna melanoma (LMM). In this summary, we will go over the main points of LM/LMM and talk about the unique difficulties in identifying and treating this form of skin cancer.

What Causes Lentigo Maligna Melanoma?

The main cause of developing Lentigo Maligna/Malignant Melanoma (LM/LMM), types of skin cancer, is exposure to ultraviolet radiation (UVR), specifically long-term exposure over a lifetime. Studies have shown that LM/LMM is tightly linked with constant exposure to UVR, unlike other forms of skin cancer like nodular melanoma (NM) and superficial spreading melanoma (SSM), which are linked to periods of heavy UVR exposure.

Interestingly, a study in Australia found that the risk of LM increased with the number of years spent living in the country, hours spent in sunlight, existing sun damage, and a history of non-melanoma skin cancer. LM/LMM typically appears on the face, an area often exposed to the sun, while SSM and NM are more likely to appear on the trunk in men and legs in women, areas that are usually covered up.

It’s worth noting that LM tends to appear in older people compared to SSM and NM, likely because older people have been exposed to the sun for a longer period in their life. Other factors that could increase the risk of LM include previous exposure to x-rays, hormonal estrogen/progesterone, and non-permanent hair dyes.

People with genetic conditions that make them more sensitive to the sun, such as oculocutaneous albinism, xeroderma pigmentosum, Werner Syndrome, and porphyria cutanea tarda, are also more likely to develop LM. There’s no evidence to suggest that smoking or drinking alcohol are connected to developing LM.

Risk Factors and Frequency for Lentigo Maligna Melanoma

LM/LMM is the third most common type of skin cancer known as melanoma. It makes up about 4 to 15% of all melanomas, and between 10 and 26% of those found on the head and neck. People commonly receive a diagnosis around the ages of 66 to 72, which is older than the typical 45 to 57 years for other types of melanoma. Women tend to be affected more and are usually slightly older when diagnosed.

In recent years, the rate of LM/LMM has been increasing. Data from Olmstead County, Minnesota, noted an increase from 2.2 cases per 100,000 people per year between 1970 and 1989 to 13.7 cases per 100,000 people per year between 2004 and 2007.

• A similar increase was also noted in the Netherlands.
• In California, there was a sharp 52% increase especially in people aged 45 to 64, between 1990 and 2000.

However, it’s uncertain whether these figures represent a true rise or if they are due to improved detection methods. There is a faster increase in cases of MIS, a non-invasive type of melanoma, which suggests that improved detection may play a role in these rising numbers.

Signs and Symptoms of Lentigo Maligna Melanoma

Lentigo maligna (LM) often appears as an irregular brown mark or spot on the sun-damaged skin of elderly individuals. This brown spot may vary in color from light brown to black, may not be perfectly symmetrical, and often has unclear edges. These spots can develop patchy, disconnected areas as they grow. In general, these lesions don’t cause symptoms. However, if the tumors progress, they might cause discomfort, burning sensation, itchiness, or even bleeding. These spots are most commonly found on the head or neck (86% of cases), predominantly on the cheeks. Cases outside the face typically occur on the extremities in women and on the back in men.

The nature of LM is such that it remains in its place of origin, maintaining its smooth, non-raised appearance. However, if the lesion begins to invade deeper skin layers, it may become raised or palpable. Lesions grow slowly and can often be mistaken for sun spots or other harmless skin conditions for years, or even decades.

The overall chance of LM progressing to invasive melanoma, also known as Lentigo Maligna Melanoma (LMM), over a lifetime has been estimated to be around 5% based on studies. However, this risk may be higher in reality, as 10 to 20% of cases initially diagnosed as LM are later reclassified as LMM after further examination. The period it takes for LM to progress to LMM can vary greatly, ranging from less than 10 years to more than 50 years.

Testing for Lentigo Maligna Melanoma

When it comes to diagnosing skin conditions, it can often be tricky because some harmless skin spots, like solar lentigo (age spots) and pigmented actinic keratosis (rough, scaly patches caused by sun exposure), can look a lot like more serious ones. That’s why doctors use special tools like dermoscopy and something called reflectance confocal microscopy (RCM) to help them make accurate diagnoses.

During dermoscopy, doctors look for specific signs that indicate whether a lesion is harmless or could be something more serious like Lentigo Maligna (LM) or Lentigo Maligna Melanoma (LMM). In early stages, these more serious conditions may look like little spots of pigmentation around hair follicles. As these conditions progress, these spots begin to join together and form lines and shapes that eventually cover the entire hair follicle area. The lesion then takes on a uniform dark brown to black color.

When using RCM, doctors look for two major signs – unusual shaped tissue projections and large, round cells called pagetoid cells. They also look for three lesser signs, such as abnormal cells at the junction between the dermis and epidermis (layers of the skin), abnormal cells located in the follicles, and cells with nuclei present within the projections of skin tissue.

While these imaging techniques are very helpful, the most accurate way to diagnose these conditions is through a skin biopsy. This is when a piece of the suspicious skin is removed and sent to the lab for examination. There are different ways to do this biopsy; sometimes it involves removing the entire lesion, while other times, just a part of it is removed to be examined.

Finally, other tools such as a Wood’s lamp, which uses UV light to help visualize the skin differently, along with dermoscopy and RCM, can be helpful to determine the exact area that needs to be removed during surgery.

Treatment Options for Lentigo Maligna Melanoma

Surgical removal is usually the best treatment option. It has been found that traditional methods of removing the affected area may not be sufficient for Lentigo Maligna (LM), a type of skin cancer, as around half of these cancers require larger areas to be removed to completely clear the cancer. Therefore, recurrence rates of the cancer can be quite high (between 8% to 20%). Recently, the National Comprehensive Cancer Network suggested removing a larger area of the skin (between 0.5cm and 1.0cm) when dealing with this type of skin cancer.

Some studies have shown that using an even much larger margin up to 1.2 cm can achieve a 97% clearance rate for LM. Simply put, getting rid of a more significant portion of the skin enhances the chances of eradicating the entire cancerous growth. Different surgical procedures can be used to remove the affected skin, but a particular method, called Mohs micrographic surgery (MMS), is proving more superior. MMS holds an edge with recurrence rates falling between 1.8% to 1.9%, significantly lower than the 5.8%-5.9% recurrence rates observed when using another method called wide local excision (WLE).

For those who prefer not to undergo surgery or who may face higher exposure to surgical risks, a cream, imiquimod 5%, can be a good alternate treatment option. However, the effectiveness of this cream varies, with clearance rates ranging between 46% and 78%. Radiation therapy, which involves employing radiation to kill cancer cells, can also be considered. Fractionated superficial radiotherapy, a specific type of radiation therapy, has recurrence rates of between 5% to 14%. Other non-surgical treatments such as laser treatment, cryotherapy (use of extreme cold), azelaic acid, 5-fluorouracil cream, and chemical peels have been used with varying degrees of success, but there isn’t enough consistent data to conclude how effective these treatments can be.

What else can Lentigo Maligna Melanoma be?

When examining skin conditions, doctors might come across symptoms that are common to a few disorders. Some of these conditions include:

• Sunspots
• Early stage or flat seborrheic keratosis
• Lichen planus-like keratosis
• Pigmented actinic keratosis, which results from overexposure to the sun.

On a microscopic level, doctors might see skin changes that look similar to:

• Benign melanocytic hyperplasia – a harmless increase in melanocytes, the cells that produce the skin pigment melanin, usually due to sun damage
• Invasive lesions – wounds or ulcers that spread into healthy skin
• Desmoplastic melanoma – a rare form of skin cancer
• Very rarely, dermatofibrosarcoma protuberans – another rare type of cancer.

These symptoms may also present in an ulcerated acral lentiginous melanoma, which could appear on areas like the top of a toe.

What to expect with Lentigo Maligna Melanoma

The outlook for patients with LM/LMM, types of skin cancer, is very good. A study involving 270 patients who underwent complete excision of LM/LMM showed no disease-related deaths for LM and only one death for LMM. Furthermore, the survival rates were 100% after 5 years and 97.1% after 10 years.

This means that LM, on its own, doesn’t shorten a person’s life. However, if the cancer becomes invasive, the outlook is the same as with other types of melanoma, if we consider the same depth of invasion (known as the Breslow depth). If the disease spreads to other parts of the body (a process known as becoming metastatic), the prognosis can be less positive with a 5-year survival rate between 9-27%.

While death rate due to this type of skin cancer is low, the quality of life for affected patients could be significantly impacted. This is especially the case when the cancer covers a large area on the head or neck, requiring extensive surgical removal and reconstruction procedures.

Possible Complications When Diagnosed with Lentigo Maligna Melanoma

If left untreated, Lentigo Maligna Melanoma (LMM) can spread to other parts of the body, making early diagnosis and treatment extremely important. Surgery to remove LMM can result in cosmetic issues because this type of melanoma often develops on visible parts of the body like the face. Modern surgical procedures can help reduce the appearance of scars.

• Early diagnosis and treatment of LMM is crucial to prevent it from spreading
• Surgery for LMM may leave visible scars, especially when it is on the face
• Current surgical techniques can help minimize the appearance of these scars

Preventing Lentigo Maligna Melanoma

Chronic exposure to ultraviolet radiation (UVR – essentially sunlight) can cause certain skin conditions, like lentigo maligna (LM) or lentigo maligna melanoma (LMM). Hence, good sun protection practices can help prevent these conditions. The American Academy of Dermatology, a leading organization of skin specialists, regularly offers guidelines on how to avoid and treat skin cancer.

One of their most important recommendations is to wear sunscreen with a Sun Protection Factor (SPF) of 30 or more, every time you’re outside. It’s essential to reapply the sunscreen every two hours and immediately after you’ve been swimming. Also, make sure to use enough of it – roughly the amount that would fill a shot glass – to cover your entire body.

To further protect yourself from the sun, you could wear clothing labelled Ultraviolet Protection Factor or UPF, avoid being outside during the sunniest part of the day (10 am to 3 pm), and seek shade whenever possible.

Moreover, they advise everyone to keep an eye on their skin for changes. There is something called the ABCDE criteria for spotting melanoma (a type of skin cancer) which consists of Asymmetry, Border irregularity, Color variation, Diameter, and Evolution. Performing monthly checks of your skin and seeing a dermatologist or general doctor if you discover any concerning spots or changes can help catch potential cancers early.