|Classification and external resources|
|eMedicine||article/276624, article/870538, article/1100753, article/1965430|
Skin cancers are 
Greater than 90% of cases are caused by exposure to 
Decreasing exposure to ultraviolet radiation and the use of 
Skin cancer is the most common form of cancer globally accounting for at least 40% of cases.
There are three main types of skin cancer: malignant melanoma.
|Basal cell carcinoma||Note the pearly translucency to fleshy color, tiny blood vessels on the surface, and sometime ulceration which can be characteristics. The key term is translucency.|
|Squamous cell carcinoma||Commonly presents as a red, crusted, or scaly patch or bump. Often a very rapid growing tumor.|
|Malignant melanoma||The common appearance is an asymmetrical area, with an irregular border, color variation, and often greater than 6 mm diameter.|
Basal cell carcinomas are present on sun-exposed areas of the skin, especially the face. They rarely metastasize and rarely cause death. They are easily treated with surgery or radiation. Melanomas are the least frequent of the 3 common skin cancers. They frequently metastasize, and could potentially cause death once they spread.
Less common skin cancers include: keratoacanthoma, spindle cell tumors, sebaceous carcinomas, microcystic adnexal carcinoma, Pagets’s disease of the breast, atypical fibroxanthoma, leimyosarcoma, and angiosarcoma.
The BCC and the SCCs often carry a UV-signature mutation indicating that these cancers are caused by UV-B radiation via the direct DNA damage. However the malignant melanoma is predominantly caused by UV-A radiation via the indirect DNA damage.The indirect DNA damage is caused by free radicals and reactive oxygen species. Research indicates that the absorption of three sunscreen ingredients into the skin, combined with a 60-minute exposure to UV, leads to an increase of free radicals in the skin, if applied in too little quantities and too infrequently. However, the researchers add that newer creams often do not contain these specific compounds, and that the combination of other ingredients tends to retain the compounds on the surface of the skin. They also add the frequent re-application reduces the risk of radical formation.
Signs and symptoms
There are a variety of different skin cancer symptoms. These include changes in the moles, such as jagged edges to the mole and enlargement of the mole.
Basal cell carcinoma
Basal cell carcinoma usually presents as a raised, smooth, pearly bump on the sun-exposed skin of the 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
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 consist of various colors from shades of brown to black. A small amount of melanomas are pink, red or fleshy in color; these are called amelanotic melanomas which 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 pain, itching, ulceration, redness around the site, or bleeding at the site. An often-used mnemonic is “ABCDE”, where A is for “asymmetrical”, B for “borders” (irregular: “Coast of Maine sign”), C for “color” (variegated), D for “diameter” (larger than 6 mm—the size of a pencil eraser) and E for “evolving.”
Ultraviolet radiation from sun exposure is the primary cause of skin cancer. Other factors that play a role include:
- Smoking tobacco
- HPV infections increase the risk of squamous cell carcinoma.
- Some genetic syndromes including congenital melanocytic nevi syndrome which is characterized by the presence of nevi (birthmarks or moles) of varying size which are either present at birth, or appear within 6 months of birth. Nevi larger than 20 mm (3/4″) in size are at higher risk for becoming cancerous.
- Chronic non-healing wounds. These are called Marjolin’s ulcers based on their appearance, and can develop into squamous cell carcinoma.
- The use of many immunosuppressive medication increase the risk of skin cancer. Cyclosporin A, a calcineurin inhibitor for example increases the risk approximately 200 times, and azathioprine about 60 times.
A malignant epithelial tumor that primarily originates in the epidermis, in squamous mucosa or in areas of squamous metaplasia is referred to as a squamous cell carcinoma.
Macroscopically, the tumor is often elevated, fungating, or may be ulcerated with irregular borders. Microscopically, tumor cells destroy the basement membrane and form sheets or compact masses which invade the subjacent connective tissue (dermis). In well differentiated carcinomas, tumor cells are pleomorphic/atypical, but resembling normal keratinocytes from prickle layer (large, polygonal, with abundant eosinophilic (pink) cytoplasm and central nucleus).
Their disposal tends to be similar to that of normal epidermis: immature/basal cells at the periphery, becoming more mature to the centre of the tumor masses. Tumor cells transform into keratinized squamous cells and form round nodules with concentric, laminated layers, called “cell nests” or “epithelial/keratinous pearls”. The surrounding stroma is reduced and contains inflammatory infiltrate (lymphocytes). Poorly differentiated squamous carcinomas contain more pleomorphic cells and no keratinization.
The risk of developing skin cancer can be reduced through a number of measures including: decreasing indoor tanning and mid day sun exposure, increasing the use of sunscreen, and avoiding the use of tobacco products.
There is insufficient evidence either for or against screening for skin cancers.
Treatment is dependent on type of cancer, location of the cancer, age of the patient, and whether the cancer is primary or a recurrence. Treatment is also determined by the specific type of cancer. For a small citation needed]. In general, melanoma is poorly responsive to radiation or chemotherapy.
For low-risk disease, radiation therapy (squamous cell carcinoma.
Mohs’ micrographic surgery (Mohs surgery.
Currently, surgical excision is the most common form of treatment for skin cancers. The goal of reconstructive surgery is restoration of normal appearance and function. The choice of technique in reconstruction is dictated by the size and location of the defect. Excision and reconstruction of facial skin cancers is generally more challenging due to presence of highly visible and functional anatomic structures in the face.
When skin defects are small in size, most can be repaired with simple repair where skin edges are approximated and closed with sutures. This will result in a linear scar. If the repair is made along a natural skin fold or wrinkle line, the scar will be hardly visible. Larger defects may require repair with a skin graft, local skin flap, pedicled skin flap, or a microvascular free flap. Skin grafts and local skin flaps are by far more common than the other listed choices.
Skin grafting is patching of a defect with skin that is removed from another site in the body. The skin graft is sutured to the edges of the defect, and a bolster dressing is placed atop the graft for seven to ten days, to immobilize the graft as it heals in place. There are two forms of skin grafting: split thickness and full thickness. In a split thickness skin graft, a shaver is used to shave a layer of skin from the abdomen or thigh. The donor site, regenerates skin and heals over a period of two weeks. In a full thickness skin graft, a segment of skin is totally removed and the donor site needs to be sutured closed.
Split thickness grafts can be used to repair larger defects, but the grafts are inferior in their cosmetic appearance. Full thickness skin grafts are more acceptable cosmetically. However, full thickness grafts can only be used for small or moderate sized defects.
Local skin flaps are a method of closing defects with tissue that closely matches the defect in color and quality. Skin from the periphery of the defect site is mobilized and repositioned to fill the deficit. Various forms of local flaps can be designed to minimize disruption to surrounding tissues and maximize cosmetic outcome of the reconstruction. Pedicled skin flaps are a method of transferring skin with an intact blood supply from a nearby region of the body. An example of such reconstruction is a pedicled forehead flap for repair of a large nasal skin defect. Once the flap develops a source of blood supply form its new bed, the vascular pedicle can be detached.
The mortality rate of basal cell and squamous cell carcinoma are around 0.3% causing 2000 deaths per year in the US. In comparison the mortality rate of melanoma is 15–20% and it causes 6500 deaths per year.
Skin cancer result in 80,000 deaths a year as of 2010; 49,000 of which are due to melanoma and 31,000 of which are due to non-melanoma skin cancers.
In the UK in 2010, 12,818 people were diagnosed with melanoma, and about 100,000 people were diagnosed with non-melanoma skin cancer. There were 2,746 deaths from skin cancer, 2,203 from malignant melanoma and 546 from non-malignant melanoma.
More than 3.5 million cases of skin cancer are diagnosed annually in the United States, which makes it the most common form of cancer in that country. According to the Skin Cancer Foundation, one in five Americans will develop skin cancer at some point of their lives. The first most common form of skin cancer is basal cell carcinoma, followed by the squamous cell carcinoma. Although the incidence of many cancers in the United States is falling, the incidence of melanoma keeps growing, with approximately 68,729 melanomas diagnosed in 2004 according to reports of the National Cancer Institute.
The survival rate for patients with melanoma depends upon when they start treatment. The cure rate is very high when melanoma is detected in early stages, when it can easily be removed surgically. The prognosis is less favorable if the melanoma has spread to other parts of the body.
In the UK, 84,500 non-melanoma skin cancers were registered in 2007 although a study estimated that at least 100,000 cases are diagnosed each year. Most NMSCs were basal cell carcinomas or squamous cell carcinomas. In 2007, 10,672 cases of malignant melanoma were diagnosed.
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This article uses material from the Wikipedia article Skin Cancer, which is released under the Creative Commons Attribution-Share-Alike License 3.0.
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