Hyperplasia is the growth or spread of cells within a tissue or organ, excessive in comparison to normal growth. Hyperplasia is classified as a physiological response to stimulus. Its cells are still subject to regulation by control mechanisms. This contrasts with neoplasia, where cell proliferation is non-physiological, and does not respond to common stimuli.

Hyperplasia causes may include (some are not confirmed):

Chronic inflammatory response

Damage/disease compensation

Demand increase

Hormone dysfunction

Hormone injection

Muscle stretching

Pregnancy


Some cases of hyperplasia are harmless. Hyperplasia responses can be normal and even useful (such as in the female body's preparation for breast feeding).

However, results of hyperplasia may include:

Benign tumor

Organ enlargement

Hyperplasia may present itself in different locations in the body, and in different forms. It may be classified clinically as one type or another.

Common forms of hyperplasia include:

Benign prostatic hyperplasia

Breast hyperplasia

Compensatory liver hyperplasia

Congenital adrenal hyperplasia

Endometrial hyperplasia

Focal epithelial hyperplasia

Sebaceous hyperplasia