Melanoma

Melanoma is a cancer of melanocytes, cells that produce the brown-black skin pigment melanin. Melanocytes originate in cells of the neural crest and migrate during embryogenesis, principally to the epidermis, eyes, and some mucous membranes (mouth, nose, esophagus, anus, genitourinary organs, and conjunctiva). Cutaneous melanoma afflicts mainly fair-skinned people of European origin, among whom sun exposure is the major cause. Five-year relative survival can exceed 90%. Invasive cutaneous melanoma in US whites occurs mostly on the trunk (34%), and upper limbs and shoulders (26%). Melanoma incidence rates have been increasing predominantly in European-origin populations. Ultraviolet (UV) radiation, from the sun or artificial tanning devices, probably both initiates and promotes melanoma. Nevi are markers of increased melanoma risk and direct precursors in some cases; nevus-prone people may require only modest sun exposure to initiate melanoma. Other risk factors include family history and sun sensitivity.