Hyperplasia

Hyperplasia (from ancient Greek ὑπέρ huper, "over" + πλάσις plasis, "formation") or hypergenesis, means increase in number of cells/proliferation of cells. It may result in the gross enlargement of an organ and the term is sometimes mixed with benign neoplasia / 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 cell size, whereas hyperplasia involves an increase in the number of cells.