Increase in the number of cells in an organ or tissue, resulting in increased volume of the organ risk tissue.
Occurs in tissues able to synthesize DNA, permitting mitotic division.
May be a physiologic or a pathologic process.
Physiologic hyperplasia divided into hormonal and compensatory types.
Hormonal hyperplasia refers to the increased functional capacity of a tissue when needed.
Compensatory hyperplasia refers to the increased tissue mass after damage or partial resection.
Caused by increased local production of growth factors, increased levels of growth factor receptors, or increased activation of signaling pathways.
Ongoing changes lead to production of transcription factors that activate cellular genes, growth factor receptors, cell cycle regulators with a net increase in cellular proliferation.
In hormonal type of hyperplasia the hormones may act associated growth stimulus and trigger transcription of cellular genes.
Increase in tissue mass is achieved by proliferation and the development of new cells from stem cells.
Pathologic hyperplasia, as in endometrial hyperplasia, reflects a condition that may allow cancer proliferation.
Important in wound healing with the proliferation of fibroblasts and blood vessels in response to growth factors.
May be seen as a stimulus to growth factors associated with viral infections causing warts, and mucosal lesions with hyperplastic epithelium.