Skin cancer

Skin cancer is a malignant growth on the skin, which can have many causes, including repeated severe sunburns or long-term exposure to the sun. 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, they are named after the type of skin cell.

Types

The most common 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.

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, lotions).

Prognosis

Minor surface skin cancers are readily treatable by simple surgery, but if the cancer is allowed to grow then it will penetrate through the layers of skin and affect the lymphatic system. It may also metastasize and spread to other parts of the body.

Skin cancers which are aggressive, recurrent, or located upon 'high risk sites' of the body (central face, scalp, ears, genitalia) may require more advanced surgical approaches such as Mohs' micrographic surgery to achieve high cure rates.

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 tumour 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 malignant 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.

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 squames 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

External links

Skin Cancer Experience Documented
Photos at: Atlas of Pathology
MedlinePlus: Skincancer
SkinCancer.org
RTAnswers - Answers to Your Radiation Therapy Questions: Skin Cancer
Sun Safety for Babies and Children --University of Florida/IFAS Extension Department of Family, Youth and Community Sciences