What Is Malignant Melanoma?
Malignant melanoma is a skin cancer that, if caught early, is very curable, but if caught late, is very deadly. Although it comprises only 1 percent of skin cancers, malignant melanoma accounts for over 60% of skin cancer deaths. It is estimated that approximately 30% of melanomas occur in the lower extremities, and that 3% occur in the feet.
There are many subtypes of melanoma, but four types that are more common and more often discussed. The first is called superficial spreading melanoma, and accounts for about 70% of all melanomas. In this type, the cancer remains in the outer skin layer for many years before it becomes advanced. Overall, this type is most common on men's backs and women's legs and feet. When it occurs in the lower extremity, it tends to appear on nonweightbearing areas. Below, our Wichita podiatrist explains everything you need to know about melanoma and how it affects the feet.
Superficial Spreading Melanoma
Nodular melanoma makes up about 15% of melanomas and is much more serious than the first. In this type, a nodule develops and quickly grows deep into the skin, leaving less time for diagnosis and treatment. The nodule is generally blue or black in color, and also tends to be on nonweightbearing areas of the feet.
Nodular Melanoma
The third is lentigo maligna melanoma and is seen about 10 % of the time. This is also a slow growing tumor. These are usually found on the face, but are also common on the back or the legs.
Lentigo Maligna Melanoma
Finally, acral lentiginous melanoma makes up about 5% of all melanomas.
Acral Lentiginous Melanoma
Unlike the other melanomas, this type tends to be found in non-sun exposed areas, such as under the nails or at the tips of the fingers and toes. It is most common on the bottom of the heel. This is the most common form of melanoma found in dark skinned individuals. People most susceptible to this cancer are light skinned individuals with blonde or red hair and blue eyes. This includes people who freckle or burn easily. Unlike other skin cancers, melanoma tends to occur on skin that was severely burned several times during the person's youth.
How Does Melanoma Feel?
Some are painful, others are not. Those most likely to be painful are in areas that are easily irritated by clothing, or those that are more advanced in their growth.
How to Check for Melanoma
First, your doctor will examine the lesions, looking for what's called the ABC's. The 'A' is for asymmetry, in other words, whether or not each side of the lesion looks the same. If it looks the same on both sides, it's usually not a melanoma. The 'B' is for border. Lesions with smooth borders are generally not serious, whereas irregular borders are more indicative of a tumor. 'C' indicates color. Is the lesion all one color, or is it several colors? Multiple colors is generally not a good sign. 'D' indicates diameter. The diameter should be less than 6mm. 'E' is for elevation or enlargement. Benign lesions will grow slowly, malignancies like a melanoma grow quickly.
If your doctor suspects the lesion may be cancerous, a biopsy will be done. In most cases this test will confirm whether or not the lesion must be removed. If the biopsy shows the lesion is cancerous and must be treated, your doctor will perform a variety of other tests. The types of tests done will depend greatly on the details of the biopsy report. Blood tests are usually routine. Many doctors will use a special low powered ultraviolet or black light, called a Woods lamp, to help see how big the lesion is. If the lesion is deep, your doctor may want a chest x-ray, bone scan, MRI, or CT to help determine if the cancer has spread to other areas of your body. There are several other important tests that are discussed below.
What Causes Melanoma?
There are several factors that increase the likelihood of developing a melanoma. Probably the most important is long term exposure to ultraviolet sunlight. This type of light damages the DNA in your skin. DNA is the substance responsible for making new skin. When it's damaged, it creates abnormal tissue, such as a melanoma. Age is another important factor in the development of melanoma. Several things happen as we age. Normally, our bodies have protective mechanisms that repair DNA when it is damaged. As we age, our ability to repair damaged DNA is compromised and the likelihood of generating healthy new skin is not as good. Also, as the DNA itself ages, it is more likely to create errors as it is making new skin cells. Finally, our body is less able to heal itself as it grows older. A third factor is what is called an immunocompromised state. This occurs when the body's normal defense system is not functioning properly. Many conditions can cause this, including diabetes, AIDS, and being on long term steroids.
What Can I Do For Melanoma?
The most important thing is prevention (discussed below). Keep a close eye on any moles or sores you have. If you have a sore that is healing slowly, or you notice a mole growing, changing color, or becoming painful, see your doctor immediately.
What Will My Doctor Do For Melanoma?
Any suspicious lesion will be biopsied. If the biopsy shows a melanoma, the lesion will have to be removed. Unfortunately, up to 3cm of surrounding skin will have to be removed along with the original lesion. This means that if the melanoma is on the foot, where there is relatively little skin, the surgery will be more extensive, at the minimum requiring a skin graft or flap, and often necessitating partial amputation. Depending on how deep the lesion is, your doctor may do what's called a lymphocintigraphy or a sentinel node biopsy, to see of the cancer has spread to other parts of the body. In these tests, a special dye is injected near the lesion. If this dye is seen to accumulate in one or more lymph nodes, it means the cancer is more extensive, and those lymph nodes will usually have to be removed. Few other treatments have any significant impact on melanomas. In advanced cases of melanoma, immunotherapy with low or high dose interferon alpha may be helpful. This is a specific biologic medicine that is injected several times a week for a prolonged period of time. There are many other experimental treatments being explored.
How to Prevent Melanoma
The best way to prevent this is to avoid harmful sunlight. Wear protective clothing when out in the sun, especially during the early afternoon when the rays are most harmful. Use a sunblock of at least SPF 15, especially if you are light skinned or burn easily.
