NCI Dictionary of Cancer Terms

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The NCI Dictionary of Cancer Terms features 7,780 terms related to cancer and medicine.

Browse the dictionary by selecting a letter of the alphabet or by entering a cancer-related word or phrase in the search box.

dysplasia
(dis-PLAY-zhuh)
Cells that look abnormal under a microscope but are not cancer.

EnlargeDrawing 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.

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.