Skin neoplasms are growths on the skin which can have many causes. The three most common skin cancers are basal cell cancer, squamous cell cancer, and melanoma, each of which is named after the type of skin cell from which it arises. Skin cancer generally develops in the epidermis (the outermost layer of skin), so a tumor is usually clearly visible. This makes most skin cancers detectable in the early stages.
Signs and symptoms:
There are a variety of different skin cancer symptoms. These include changes in the skin that do not heal, ulcering in the skin, discolored skin, and changes in existing moles, such as jagged edges to the mole and enlargement of the mole.
Basal cell carcinoma usually presents as a raised, smooth, pearly bump on the sun-exposed skin of the head, neck or shoulders. Sometimes small blood vessels can be seen within the tumor. Crusting and bleeding in the center of the tumor frequently develops. It is often mistaken for a sore that does not heal. This form of skin cancer is the least deadly and with proper treatment can be completely eliminated, often without scarring.
Squamous cell carcinoma is commonly a red, scaling, thickened patch on sun-exposed skin. Some are firm hard nodules and dome shaped like keratoacanthomas. Ulceration and bleeding may occur. When SCC is not treated, it may develop into a large mass. Squamous cell is the second most common skin cancer. It is dangerous, but not nearly as dangerous as a melanoma.
Most melanomas are brown to black looking lesions. Unfortunately, a few melanomas are pink, red or fleshy in color; these are called amelanotic melanomas. These tend to be more aggressive. Warning signs of malignant melanoma include change in the size, shape, color or elevation of a mole. Other signs are the appearance of a new mole during adulthood or new pain, itching, ulceration or bleeding. An often-used mnemonic is "ABCD", where A= asymmetrical, B= "borders" ( irregular= "Coast of Main sign" ), C= "color" ( variegated ) and D= "diameter" ( larger than 6 mm --the size of a pencil eraser).
Merkel cell carcinomas are most often rapidly growing, non-tender red, purple or skin colored bumps that are not painful or itchy. They may be mistaken for a cyst or other type of cancer.
Skin cancer has many potential causes. Examples include:
- Smoking tobacco and related products can double the risk of skin cancer.
- Overexposure to UV-radiation may cause skin cancer either via the direct DNA damage or via the indirect DNA damage mechanism. Overexposure (burning) UVA & UVB have both been implicated in causing DNA damage resulting in cancer. Because UVB is highly absorbed by the atmosphere, UVB between 10AM and 4PM is most intense. Natural (sun) & artificial UV exposure (tanning salons) are possibly associated with skin cancer.
- UVB rays primarily affect the epidermis causing sunburns, redness, and blistering of the skin when overexposed. The melanin of the epidermis is activated with UVB just as with UVA; however, the effects are longer lasting with pigmentation continuing over 24 hours.
- Chronic non-healing wounds, especially burns. These are called Marjolin's ulcers based on their appearance, and can develop into squamous cell carcinoma.
- Genetic predisposition, including "Congenital Melanocytic Nevi Syndrome". CMNS is characterized by the presence of "nevi" or moles of varying size that either appear at or within 6 months of birth. Nevi larger than 20 mm (3/4") in size are at higher risk for becoming cancerous.
- Human papilloma virus (HPV) is often associated with squamous cell carcinoma of the genitals, anus, mouth, pharynx, and fingers.
- Skin cancer is one of the potential dangers of ultraviolet germicidal irradiation.
- Deficiencies in certain vitamins and minerals.
- Arsenic poisoning is associated with an increased incidence of squamous cell carcinoma.
A 2010 study has found a relation between HPV infection and incidence of squamous cell carcinoma.
Although it is impossible to completely eliminate the possibility of skin cancer, the risk of developing such a cancer can be reduced significantly with the following steps:
Avoid the use of tobacco products.
Reducing overexposure to ultraviolet (UV) radiation, especially in early years
Avoiding sun exposure during the peak UV times during the day, typically from 10 AM to 3 PM (dependent on country) when the sun is directly overhead
Wearing protective clothing (long sleeves and hats) when outdoors
Using a broad-spectrum sunscreen that blocks both UVA and UVB radiation
Reapply sun block as per the manufacturers directions
Australian scientist Ian Frazer who developed a vaccine for cervical cancer, says that a vaccine effective in preventing for certain types of skin cancer has proven effective on animals and could be available within a decade. The vaccine would only be effective against Squamous Cell Carcinoma.
Primary health care providers should examine their patients during the course of a routine comprehensive physical examination by means of a full body screening (all areas of the body's skin surface are examined, with the use of a special light and a magnifying glass, for abnormal masses, lesions, and cancerous neoplasms like BCC, SCC, and MM). Referrals or visits to a dermatologist will usually include this as a first part of the examination. Many times, hospitals, doctor's offices, and dermatologist's offices will perform these for the general public as part of a mass screening program done at certain times during the year, and these are usually free or are low-priced and thus are often very popular. If necessary, skin cells from the outer epidermis can be scraped off or an actual biopsy performed, and the results examined for pathologies.