Skin cancer

From Wikipedia, the free encyclopedia

Skin cancer is a malignant growth on the skin, which can have many causes. 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. There are three common types of skin cancer each of which are named after the type of skin cell. In the case of UV damage, sun screen is one of the better forms of prevention.

Skin cancers are the fastest growing cancers in the United States and in the USA represent the most commonly diagnosed malignancy, surpassing lung, breast, colorectal and prostate cancer. in the US, over 1 million people will be diagnosed with skin cancer in 2007. [1]

**Skin cancer**
*Classification & external resources*
ICD-10	C 43.-C 44. (ICD-O 8010-8720)
ICD-9	172, 173

1 Risk Factors
2 Types
3 Prevalence
4 Signs and symptoms
5 Treatment
6 Prevention
- 6.1 Non-melanoma skin cancer
- 6.2 Melanoma
7 Pathology
8 See also
9 References
10 External links

[edit] Risk Factors

Skin cancer is most closely associated with chronic inflammation of the skin. This includes:

sun-burn or excessive sun-damage - especially early in life. UVA & UVB have both been implicated in causing DNA damage resulting in cancer. Sun exposure between 10AM and 4PM is thought to be most harmful. Natural (sun) & artificial UV exposure (tanning salons) are associated with skin cancer.
chronic non-healing wounds, especially burns - this is called Marjolin's Ulcer based on its appearance.
genetic predisposition including Congenital Melanocytic Nevi syndrome which is the presence of "nevi" or moles of varying size that people are either born with or that appear within 6 months of birth. Nevi larger than 20 mm (3/4") in size are at high risk for becoming cancer.

(Greenfield's Surgery 4th ed.)

[edit] Types

The most types are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) which may be locally disfiguring but unlikely to spread to other parts of the body. The most dangerous type is malignant melanoma, which can be fatal if not treated early, but forms only a small proportion of all skin cancers.

Other types of skin cancer are:

[edit] Prevalence

Skin cancer is an increasingly common condition, in part attributed to increased exposure to ultraviolet radiation. The increased exposure is mainly due to the recent popularity of sun tanning (sun bathing). Lighter-skinned individuals are more vulnerable. In the United States, about one out of every three new cancers arises from skin. Skin cancers are often curable. Barriers which reduce UV exposure are effective in preventing skin cancers (clothes, hats, creams, butter, lotions).

[edit] Signs and symptoms

There are a variety of different skin cancer symptoms. These include sores or changes in the skin that do not heal, ulcers in the skin, discoloring in parts of the skin, and changes in existing moles.

Basal cell carcinoma usually looks like 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.

Squamous cell carcinoma is commonly a red, scaling, thickened patch on sun-exposed skin. Ulceration and bleeding may occur. When SCC is not treated, it may develop into a large mass.

Most melanomas are brown to black looking lesions. Signs that might indicate a malignant melanoma include change in size, shape, color or elevation of a mole. The appearance of a new mole during adulthood, or new pain, itching, ulceration or bleeding of an existing mole should be checked.

[edit] Treatment

Most skin cancers, SCC, BCC, Melanomas, can be treated by removal of the lesion making sure that the edges (margins) are free from tumor. The excisions provide the best cure for early and hi-risk disease.

For lo-risk disease, radiation therapy and cryo-therapy (freezing the cancer off) can provide adequate control of the disease but still has lower overall cure rates compared to surgery.

Moh's Microsurgery is a technique where the cancer is removed with the least amount of surrounding tissue and the edges checked immediately to see if tumor is found. This provides the opportunity to remove the least amount of tissue and provide the best cosmetic surgery, especially when surface area is limited, in places such as the face. Cure rates are equivalent to wide excision. Special training is required in this technique.

In the case of disease that has spread (metastasized) further surgical or chemotherapy may be required. (Greenfield's Surgery 4th ed.)

[edit] Prevention

[edit] Non-melanoma skin cancer

Non-melanoma skin cancers include basal cell carcinoma and squamous cell carcinoma.

reducing exposure to ultraviolet (UV) radiation
- changing patterns of outdoor activities, sun exposure avoidance 11 am - 3 pm
- wearing protective clothing (long sleeves and hats) when outdoors
- using efficient sunscreens is recommended. It is a simple step to reduce your chance of cancer. You should wear some type of sunscreen everyday.

[edit] Melanoma

avoiding sunburns, especially in childhood and adolescence
reducing exposure to ultraviolet (UV) radiation
- changing patterns of outdoor activities, sun exposure avoidance 10 am - 4 pm
- wearing protective clothing (long sleeves and hats) when outdoors
- using sunscreen

It is generally accepted that UV exposure is the greatest risk factor in melanoma development but skeptics have noted that there is absolutely no proven data that links moderate sun exposure with the appearance of melanoma.

[edit] Pathology

Squamous cell carcinoma is a malignant epithelial tumor which originates in epidermis, squamous mucosa or areas of squamous metaplasia.

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. 1