Skin Cancer

Skin Cancer



Dawn Tiedemann



Melanoma



DEFINITION


The three main types of cells in the outer layer of the skin (epidermis) are squamous cells, basal cells, and melanocytes. Skin cancers are malignant lesions that occur in these cells, including the less aggressive basal cell and squamous cell carcinomas and the more aggressive malignant melanoma. Melanoma is a malignant tumor of melanocytes. Melanocytes are the cells that make the pigment melanin and they are derived from the neural crest. Although most melanomas arise in the skin, they may develop on mucosal surfaces or at other sites to which neural crest cells migrate.



INCIDENCE


The American Cancer Society estimates 59,940 cases of melanoma will be diagnosed in 2007. During the 1970s, the incidence of melanoma increased by about 6% per year. Since 1980, the rate of increase has slowed to slightly less than 3% per year, perhaps because of increased awareness and promotion of preventive measures. Melanoma is primarily a disease of whites; the incidence is 10 times greater than in blacks.



ETIOLOGY AND RISK FACTORS


Skin cancers are generally associated with exposure to ultraviolet light found in sunlight but can be found anywhere on the skin.



• Prior melanoma


• Family history of melanoma


• Nevi (moles), particularly if numerous, large, or unusual


• Fair complexion


• History of unprotected or excessive sun exposure


• Severe sunburns as a child


• Use of tanning beds


• More common in the southern latitudes of the Northern Hemisphere


• Exposure to coal tar, pitch, creosote, arsenic compounds, or radium


• History of radiation or ultraviolet treatments


• Individuals with immune suppression from disease or medical treatment



SIGNS AND SYMPTOMS


Generally a change in the size, shape, color, or diameter of an existing skin lesion or the appearance of a new lesion causes the suspicion of a skin cancer to be raised. They usually occur on sun-exposed areas but can occur anywhere.


Melanoma: signs are usually promoted as “ABCD”:



A: Asymmetry (one half of the mole does not match the other)


B: Border (irregular)


C: Color, such as blue, black, or variation in the same mole


D: Diameter greater than 6 mm



DIAGNOSTIC WORKUP


Skin cancer screening is by self-examination and clinical visual examination of the skin to identify any suspicious lesions. It is often difficult to distinguish a benign pigmented lesion from an early melanoma. A biopsy, preferably by local excision of the entire lesion, should be performed to make a definitive diagnosis. A suspicious pigmented lesion should never be shaved off or cauterized. Additionally, computed tomographic scans are done to identify any potential sites of metastasis: brain, lung, liver, regional lymph nodes, and skin.



HISTOLOGY


Following is a list of clinicopathologic cellular subtypes of malignant melanoma. These subtypes should be considered descriptive terms only. They do not have any prognostic or therapeutic significance:



• Superficial spreading, which commonly arises in preexisting nevi and usually presents with irregular borders; scaly, crusty surface; and in a variety of colors


• Nodular, which is raised, usually blue-black in color, and has a rapid vertical growth phase


• Lentigo maligna is a large freckle-like lesion, tan to black in color, or a raised nodule with notched borders.


• Acral lentiginous (palmar/plantar and nailbed) is usually flat and irregular in shape, varies in color, may be smooth or ulcerated, raised or flat.


• Miscellaneous unusual types:


˚ Mucosal lentiginous (oral and genital)

˚ Desmoplastic

˚ Verrucous


STAGING


Various methods have been used to stage melanoma. Currently vertical thickness, presence or absence of ulceration, lymph node involvement, and distant metastasis are factors used in staging. Several systems are used:



• Clark’s level: scores the primary melanoma lesion according to levels I-V that describe penetration into the various layers of the skin


• Breslow thickness: measures the actual vertical thickness of the lesion in millimeters


• TNM (tumor, nodes, metastasis): uses the Clark level and Breslow thickness measurements and involvement of lymph nodes, presence of ulceration, and distant metastasis, to assign stages. (See table on pages 133–134).



TREATMENT




• Surgical excision with a wide margin if possible (depending on tumor thickness) is the primary treatment for melanoma. Skin grafting may be needed to close the wound.


• Regional lymph node dissection is done in the case of palpable lymph nodes, to identify regional spread, and to assist in controlling the disease through lymphatic spread. In the case of nonpalpable lymph nodes where the primary melanoma is 1 to 4 mm thick, the “sentinel” lymph node is identified and this node is examined to determine the presence of disease before additional nodes are removed. This technique helps to avoid extensive lymph node dissections. The “sentinel” node is identified through lymphoscintigraphy and identifies the first lymph node that drains the tumor bed.


• Surgery may also be done for palliation of painful or draining lesions.


• Radiation is generally not used because melanoma can be resistant to radiation but may be done if the tumor is small or in cases of brain metastasis.


• Chemotherapy with interferon alfa-2b may be used as adjuvant therapy. For metastatic disease, dacarbazine, temozolomide, cisplatin, thalidomide, interferon alfa-2b, interleukin-2, or carmustine have been used.

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Mar 1, 2017 | Posted by in NURSING | Comments Off on Skin Cancer

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