An Overview of Non-melanoma Cancers and Melanoma

Non-Melanoma Skin Cancer • There are two major types of non-melanoma skin cancers (NMSC): squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). • NMSCs are the most common cancers in humans in North America. • Basal cell carcinoma is the most common type of skin cancer. • It is locally destructive and causes significant morbidity, but rarely metastasizes. • New growths or sores that don’t heal are a warning sign for skin cancer. Melanocytic Nevi Dysplastic nevi (Clinically atypical nevi) • Are a type of acquired melanocytic lesion that has been identified as a marker and potential precursor for cutaneous melanoma • May be sporadic or familial • Changing lesions or atypical lesions, in which differentiation of early melanoma is not possible, should be excised Cutaneous Melanoma Early diagnosis and complete surgical excision are critical to improving the prognosis of melanoma. Melanomas diagnosed at an early stage are highly curable (melanoma in situ – five year survival rate = 100%), whereas the median survival for metastatic melanoma is poor (median survival = 6-10 months for Stage IV melanoma), encouraging efforts to improve early diagnosis. Classification of Cutaneous Melanoma: Four clinical and pathologic subtypes of melanoma have been identified: 1. Superficial spreading melanoma 2. Acral lentiginous melanoma 3. Lentigo maligna melanoma 4. Nodular melanoma. Diagnosis: • Certain phenotypic risk factors for melanoma can be identified on history and physical exam: • light skin pigmentation • presence and number of atypical/ • number of melanocytic nevi dysplastic nevi • ease of developing sunburn • blond or red hair • family history of melanoma • freckling (two first-degree relatives) • prior history of melanoma • blue-green eyes • A cardinal feature of a skin lesion that proves to be a melanoma is a change observed over a period of months. • A change in a pre-existing nevus, a new pigmented lesion appearing in an adult, or the development of any symptoms (itching) or signs (enlargement, asymmetry, darkening, bleeding, ulceration) should prompt referral for assessment of a pigmented lesion. • The most common change noted initially in early melanoma is increased size (diameter) and color change. • Proposed criteria for clinical recognition of an early melanoma is summarized by the ABCD acronym: A = Asymmetry; B = Border irregularity; C = Color variation; D = Diameter > 6 mm. • Small superficial spreading and nodular melanomas may lack some or all of these clinical criteria. • Any pigmented lesion in which the diagnosis of melanoma is suspected should be biopsied. • A complete excision with narrow margins is the recommended type of biopsy for suspected melanoma. • An incisional biopsy or punch biopsy may be performed when the lesion is large and complete excision cannot be easily performed. • Shave biopsies should not be performed if a melanoma is suspected, as the lesion can be transected, precluding accurate determination of umor thickness. • The vertical thickness of the primary tumor as measured by Breslow and ulceration are the most important histologic factors in determining prognosis of primary (nonmetastatic) melanoma as increasing thickness of primary melanoma portends a progressively worse prognosis.

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Tags: basal cell carcinoma,  skin cancer,  skin lesion,  skin pigmentation,  type of skin cancer,