-IBIS-1.5.0-
tx
cutaneous system
skin cancer
diagnoses

definition and etiology

definition:
malignancy of the skin

etiology:
Skin cancer is the most common type of cancer. Estimates suggest that 40-50% of people living to 65 years old will have at least one cancerous lesion of the skin. Skin cancer is also the most common recurrent cancer, with from 50-60% of people getting another cancerous lesion after they have had cancer previously (usually, the recurrent lesion is also a skin cancer). Risk factors known to increase the development of skin cancer include:
sun exposure (ultraviolet rays): particularly on the uncovered body areas such as the face and hands; fair-skinned peoples and those with occupational sun exposure (farmers, ranchers, sunbathers, sailors, etc.) are at greater risk; this factor may dramatically increase the incidence of skin cancers if the ozone layer continues to be depleted
chemical carcinogens: coal tars, agricultural sprays containing arsenic, molten metal industries
irradiation
genetic defects: in patients with xeroderma pigmentosum or basal cell nevus syndrome
poor diet: low in the protective anti-oxidant and anticancer nutrients such as vitamins A, C, E, and the mineral selenium; high in foods that deplete tissue mineral stores or contain harmful substances (sugar, preservatives, commercial meat and poultry, fried foods, etc.)

signs and symptoms

signs and symptoms: Skin cancers are external in 90-95% of presentations. Some may itch.

early:
• loss of skin margins
• pigment varies within the lesion
• irregular hyperkeratotic regions

late:
• roughened region of skin that scabs and rescabs, but doesn't totally heal
• chronic ulcer or bleeding lesion that is not from any other known pathology or condition
• ulcer present in an area that was irradiated, previously burned, or an old scar
• suspicious skin lesion in a high risk person (see "etiology")
• chronic lesions in unusual sites

specific types of cancers:
basal cell carcinoma: Although the lesion may appear in a variety of ways, it commonly begins as a small, shiny papule that grows slowly until it develops a pearly border of telangiectasia with a central ulcer. The lesion continues to grow slowly while chronically bleeding and crusting and never completely healing over.
squamous cell carcinoma: scaly lesion, keratotic, and slightly raised, with an irregular border and a shallow persistent ulceration; later lesions become friable, have large ulcerations, and chronic crusting
malignant melanoma (MM): There are several different types of this tumor, all with varying degrees of invasion and metastasis. Sources differ regarding the origin of MM; some say most derive from preexisting benign nevi, while others say most derive from melanocytes of normal skin and less than a third derive from moles. When MM does come from a mole, there is frequently itching, bleeding, and a change in the appearance (size, thickness and color) of the mole. Color of the lesion varies from black, tan, grey and red. There may be small dermal nodules surrounding the lesion. Superficial spreading melanoma is the most common type of MM, accounting for 60-70% of MM; the other two types are lentigo-maligna melanoma and nodular melanoma.

lab findings:
• (+) excisional biopsy
• X-rays and radioisotopic scans to detect metastatic disease

course and prognosis

Although approximately 4,000 people die yearly from skin cancer, most of those deaths are preventable. Early diagnosis carries a much better prognosis because skin cancers are easily treatable by excision when confined to local tissues, but become a much more serious problem when metastasis has begun. Additionally, prevention of even early cancers can be accomplished by appropriate management of risk factors, particularly sun exposure in sensitive skin types.

• Basal cell carcinoma rarely metastasizes and surgical excision, irradiation or electrodesiccation and curettage is recommended.
• With squamous cell carcinoma, by the time of diagnosis, about 1/3 of lingual or mucosal lesions have metastasized. Conventional treatment is surgical excision or irradiation.
• Malignant melanoma is the most serious skin cancer, and survival depends on: if metastasis has occurred and to what organs, the primary site, the patient's sex, and the particular type of lesion. If metastasis has occurred, generally the 5-year survival rate drops to 30-50%, depending on the type of MM. Treatment for MM includes excision (possibly with regional lymph node dissection), and hormonal therapy. MM is resistant to irradiation and chemotherapy.
• In all the skin cancers, early detection and treatment will lead to cure (but may not prevent recurrence).

differential diagnosis

• Paget's disease of the nipple
• Kaposi's sarcoma
• keratoacanthoma
• actinic and senile keratosis: these become malignant in only 1% of patients
• seborrheic keratosis
• arsenical keratosis
• Bowen's disease
• radiation dermatitis
• keratoacanthoma
• basal cell nevus syndrome
• SLE
• other benign skin conditions


footnotes