Melanocytic neoplasms constitute a spectrum of benign and malignant skin tumors that have distinct clinical, morphological, and molecular genetic profiles. Melanomas are neoplasms of melanocytes that have the potential to metastasize or are on an evolutionary pathway in which the acquisition of that potential is likely. Melanomas may develop within a pre-existing benign melanocytic nevus, but the great majority develop de novo. Intermittent high dose UV radiation is the major environmental risk factor for melanoma, but genetic factors undoubtedly play an important role. Melanomas are the most important group of cutaneous malignancies because of their inherent capability for metastasis.
The most commonly affected anatomic sites are the face in both sexes, the ear, head, neck, back, and shoulders in men, and the legs in women. Melanomas begin as macules that may progress to plaques and tumors. Most begin as faintly uniform brown macules with slightly irregular borders. Over time, they enlarge as they develop variegations in pigmentation and more irregular contours. These features have been associated with the mnemonic ABCD (asymmetry, irregular border, uneven color, diameter greater than 6 mm). Eventually, all or a part of the lesion may become elevated; hence, some have advocated adding "E" to the ABCD mnemonic. Elevated lesions in the form of papules, plaques, nodules, and tumors may develop as malignant melanomas evolve. Nodules and tumors tend to ulcerate. Such ulceration is a consequence of the neoplastic process itself, rather than of external trauma. Pedunculation is a rare type of nodulation of malignant melanoma. Nodules are usually pigmented but occasionally may be devoid of pigment and are then termed amelanotic malignant melanoma. When an amelanotic melanoma ulcerates, it may resemble a pyogenic granuloma.
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Complete Guide to Preventing Skin Cancer. We all know enough to fear the name, just as we do the words tumor and malignant. But apart from that, most of us know very little at all about cancer, especially skin cancer in itself. If I were to ask you to tell me about skin cancer right now, what would you say? Apart from the fact that its a cancer on the skin, that is.