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  • Ulceration - A condition in which the epidermis that covers a portion of the primary melanoma is not intact. Ulceration is determined by microscopic evaluation of the tissue by a pathologist.
  • Ultrasound - A procedure using sound waves that allows physicians to get an inside view of soft tissues and body cavities.
  • Ultraviolet (UV) Radiation (Ultraviolet Light) - Also called ultarviolet light. The part of sunlight that is invisible to the human eye. Some wavelengths of UV radiation filter through the earth's atmosphere and enter the body through the skin and eyes. UV radiation can burn the skin and cause melanoma and other types of skin cancer.
  • Ultraviolet Light - See Ultraviolet Radiation
  • UV Index - A daily prediction of the strength of the sun's ultraviolet rays for a region.
  • UVA Rays - Long-wavelength ultraviolet (UV) rays (320 to 400 nm) given off by the sun, tanning beds, and sunlamps. They enter the skin more deeply than UVB rays, cause premature aging of the skin, and are believed to cause skin cancer.
  • UVB Rays - Medium-wavelength (290 to 320 nm) "burning rays" of the sun that are the primary cause of sunburn. They are considered the main cause of basal- and squamous-cell carcinoma, as well as a significant cause of melanoma.
  • UVC Rays - Short-wavelength ultraviolet rays (200 to 290 nm) absorbed by the earth's ozone layer, which do not reach the earth.