hyperplasia
Meaning of hyperplasia: More cells than there should be in a tissue, which is not the same thing as bigger cells or abnormal ones.
Definition of hyperplasia
Hyperplasia is an increase in the number of cells in an organ or tissue, which makes the tissue larger. The cells themselves remain normal in appearance and behavior, and the growth is a response to a stimulus such as a hormone, an irritation or a demand for more function. Remove the stimulus and the process usually stops, which separates it from cancer.
How hyperplasia is built
- hyper- Prefix · Greek above normal, excessive
- -plasia Suffix · Greek formation, growth, development
A medical term is read from its ending backwards: the suffix first, then the prefix, then the root. See all 223 word parts.
How does it differ from similar-sounding terms?
Four words are constantly confused, and the difference between them is the difference between a normal response and a cancer.
| Term | What changes | Reversible? |
|---|---|---|
| Hyperplasia | More cells, each one normal | Usually, if the stimulus stops |
| Hypertrophy | The same number of cells, each larger | Usually |
| Dysplasia | Cells disordered and abnormal in appearance | Sometimes |
| Neoplasia | Growth that continues without a stimulus | No |
When is it a normal response?
Often. Breast tissue expands in pregnancy under hormonal drive. The womb lining rebuilds after every period. Bone marrow raises red cell output at altitude. Liver tissue regrows after part of it is removed. Skin thickens where it is repeatedly rubbed, which is what a callus is. In each case the tissue is doing exactly what it should, in proportion to the demand placed on it, and settles once the demand ends.
When does it cause trouble?
Two situations. The first is where the enlargement itself causes symptoms even though the cells are normal, the standard example being benign enlargement of the prostate obstructing the flow of urine. The second is where prolonged stimulation increases the chance that an abnormal cell will appear. Endometrial hyperplasia, driven by estrogen unopposed by progesterone, is the clearest instance, and it is graded according to whether the cells have begun to look abnormal. That grading is what matters, because atypical hyperplasia, in which the extra cells are also disordered, carries a meaningfully raised risk of progressing to cancer, whereas the simple form largely does not. The same distinction applies in breast tissue.
How is it identified?
Enlargement can be felt or imaged, but the distinction between the categories above requires a tissue sample under the microscope. This is why an enlarged organ prompts a biopsy rather than a conclusion, and why a report will specify whether atypia is present rather than stating hyperplasia alone.
Used in a sentence
The biopsy showed endometrial hyperplasia without atypia.
Good to know
Hyperplasia with atypical cells carries a materially different outlook from the simple form, and only examination of a tissue sample can separate the two.
Word origin
Where “hyperplasia” comes from
From the Greek hyper, meaning over or above, plus plasis, meaning formation or molding.