Abnormal cellular growth may result in either a decrease or an increase in the mass of the involved tissue. Both hyperplasia and hyperophy are found in:

Uterine myometrial hyperplasia and hyperophy are seen during pregnancy (hormone-induced). Hyperophy results from increased amounts of cytoplasm and cytoplasmic organelles in cells.Hyperplasia results when cells of a tissue are stimulated to undergo mitotic division, thereby increasing the number of cells. Ref: Chandrasoma P., Taylor C.R. (1998). Chapter 16. Disorders of Cellular Growth, Differentiation, & Maturation. In P. Chandrasoma, C.R. Taylor (Eds), Concise Pathology, 3e.