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hyperplasia

(HY-per-PLAY-zhuh)
An increase in the number of cells in an organ or tissue. These cells appear normal under a microscope. They are not cancer, but may become cancer.
Drawing of four panels showing how normal cells may become cancer cells. The first panel shows normal cells. The second and third panels show abnormal cell changes called hyperplasia and dysplasia. The fourth panel shows cancer cells.Enlarge this image in new window
Normal cells may become cancer cells. Before cancer cells form in tissues of the body, the cells go through abnormal changes called hyperplasia and dysplasia. In hyperplasia, there is an increase in the number of cells in an organ or tissue that appear normal under a microscope. In dysplasia, the cells look abnormal under a microscope but are not cancer. Hyperplasia and dysplasia may or may not become cancer.
Search NCI's Dictionary of Cancer Terms