HyperplasiaΒ (fromΒ ancient Greek ὑπέρ huperΒ 'over' + πλάσις plasisΒ 'formation'), orΒ hypergenesis, is an enlargement of an organ or tissue caused by an increase in the amount ofΒ organic tissueΒ that results fromΒ cell proliferation.[4|4]Β It may lead to theΒ gross enlargementΒ of an organ, and the term is sometimes confused with benignΒ neoplasiaΒ orΒ benign tumor.[5|5]

Hyperplasia is a common preneoplastic response to stimulus.[6|6]Β Microscopically, cells resemble normal cells but are increased in numbers. Sometimes cells may also be increased in size (hypertrophy).[7|7]Β Hyperplasia is different from hypertrophy in that theΒ adaptive cell changeΒ in hypertrophy is an increase in theΒ sizeΒ of cells, whereas hyperplasia involves an increase in theΒ numberΒ of cells.[8|8]