Hyperplasia

Hyperplasia (from Ancient Greek ὑπέρ (hupér) 'over' and πλάσις (plásis) 'formation'), or hypergenesis, is an enlargement of an organ or tissue caused by an increase in the amount of tissue that results from cell proliferation. It may lead to the gross enlargement of an organ, and the term is sometimes confused with benign neoplasia or benign tumor. Hyperplasia is a common preneoplastic response to stimulus. Microscopically, cells resemble normal cells but are increased in numbers. Sometimes cells may also be increased in size (hypertrophy). Hyperplasia is different from hypertrophy in that the adaptive cell change in hypertrophy is an increase in the size of cells, whereas hyperplasia involves an increase in the number of cells.