There are several different types of skin cancer that you should know about, and each appears in a somewhat different fashion.
There is a common type of growth that is considered to be precancerous that known as an
Actinic Keratosis (or AK). These lesions appear as scaly or custy bumps, usually on the neck or face or other sun exposed areas. They have a dry, rough feel to them and you might some times notice one or two or with more severe sun damage, dozens can be present at one time. If an individual has more than 10 lesions, there is a higher risk of developing a squamous cell carcinoma from one of the AK’s.
Beyond the precancerous growths, here are the types of skin cancers that are usually seen most often:
Basal Skin cell cancer
By far the most common kind of skin cancer, basal skin cell cancer affects the cells in the basal layer. They show up as waxy bumps or sores that don’t heal on the face, ears, scalp or other sun exposed areas Though such cancers rarely spread to other parts of the body, this cancer can invade surrounding cells and spread to nearby areas of the skin causing damage to nearby tissue.
Squamous skin cell cancer
Squamous cell cancer occurs within the outermost cells of the epidermis. This type of skin cancer is characterized by thickened crusted lesions on sun-exposed areas. They are occasionally bothersome or irritating. While this form of skin cancer is much less common than basal cell cancer, they can be more aggressive and the cancerous tissue can spread to other parts of the body if left untreated. Statistically if they get to be larger than 1 or 2 centimeters then they are more dangerous. When they occur on the areas of the head and neck, they have the potential to invade nerve tissue and spread centrally to the brain.
Melanoma is a particularly serious form of cancer that develops from melanocytes, which are the cells that produce melanin. Melanin is the pigment that helps protect the skin against UV radiation. However, overexposure to UV rays can cause melanocytes to grow abnormally and become cancerous. This type of skin cancer can occur anywhere on the body but tends to appear more commonly on the upper body and head of men, and on the lower legs of women. It usually starts as a change in the color, size, or shape of a mole at times with rapid growth. Amelanotic melanoma is a challenging variant in which the cancerous mole has no color so it can grow without detection.
While most forms of skin cancers are rare in individuals with darker skin, basal cell and squamous cells can occur. A specific variant of melanoma that occurs on the hands and feet is called “acral lentiginous melanoma”. This is the type of melanoma that an individual with darker skin is most likely to develop and was actually the cause of death of Jamaican reggae singer Bob Marley at the age of 36 secondary to getting this condition initially on his foot.
There are other rarer types of skin cancer as well such as merkle cell tumors, sebaceous carcinoma, and atypical fibroxanthoma, these are usually detectected after a biopsy is done for a suspicious growth.
Often times a patient will have an abnormal growth on the skin and worry that this new growth is a form of cancer.
So, how can you tell the difference?
In general, there are four factors one should look at to determine if a mole might be cancerous:
- Assymetry. Benign growths such as moles will be round in appearance, while cancerous tissue will often appear asymmetric.
- Border. The edges of a benign growth will often be smooth, while cancerous tissue will appear jagged and “meld” into the skin.
- Color. Benign growths have an even color, while cancerous tissue will appear multi colored, or have a color “gradient”.
- Diameter. Moles that are larger than 6mm or the size of a pencil eraser, have a higher risk for being abnormal. However, it is possible for smaller moles to be abnormal and for larger moles to be benign. Cancerous growths tend to get larger and increase in size over time.
Some doctors also add a fifth criterion, E for evolution. A typical mole should not grow or change with time. But a cancerous growth will grow more rapidly such as doubling in size in 6 months, and might also begin to itch or bleed. These are clear warning signs.
There are other moles that meet these criteria but that are not yet cancerous. Known as dysplastic nevi or atypical moles, these growths are considered to be precancerous and especially worrisome. They are more common in individuals with a family history of melanoma. Thus, even if you have a mole that is not cancerous, monitoring and possibly removing these kinds of moles might be prudent.
In short, if you have a growth that meets any of these criteria, you should seek out a specialist immediately. One of the smartest things to do is to have a yearly skin cancer screening. With such a screening, you can have your skin evaluated by a trained health professional who will look for any suspicious growths that need to be removed. Usually this type of exam is done once a year… but if you have had a previous skin cancer, then the exam would need to be done every 6 months or sometimes every 3 months.
Statistically 70% of abnormal moles that are cancerous are first detected by family members or friends at home and not in the doctors’ office. So being aware of the criteria above has huge social benefit.