carcinoid
Meaning of carcinoid: A slow neuroendocrine tumor named for looking less dangerous than cancer, a description that has not aged well.
Definition of carcinoid
A carcinoid is a slow-growing tumor arising from hormone-producing cells scattered through the lining of the gut and the airways. It can release chemical messengers, serotonin among them, into the bloodstream. Despite a name coined to signal that it merely resembles cancer, it is malignant and able to spread, most often to the liver and sometimes many years after it is first found.
How carcinoid is built
- carcin/o Combining form · Greek cancer, carcinoma
- -oid Suffix · Greek resembling, like
A medical term is read from its ending backwards: the suffix first, then the prefix, then the root. See all 223 word parts.
Why is the name being retired?
It was coined to mean carcinoma-like, for a growth that looked like cancer under the microscope but behaved far more quietly. That reassurance turned out to be only half right, since these tumors do spread, and the label lumped together growths in different organs with very different outlooks. Current classification calls them neuroendocrine tumors and grades them by how quickly their cells divide, which predicts behavior far better than the old name ever did. Carcinoid survives in everyday speech, in the name of the syndrome, and throughout older records.
Where do they arise?
| Site | What is characteristic there |
|---|---|
| Small bowel | A common site in the digestive tract, and often found late |
| Rectum | Frequently picked up during examination done for another reason |
| Appendix | Usually a chance finding when an appendix is removed |
| Lung | A distinct group, and not linked to smoking in the typical form |
| Stomach | Often tied to long-standing loss of stomach acid |
The appendix has long been named as the commonest site, a claim that comes from how often these tumors turn up unexpectedly in a removed appendix rather than from how many arise there. The small bowel and rectum account for a larger share of the total, and any of these arising in the digestive tract may be recorded as a gastrointestinal carcinoid tumor.
What is carcinoid syndrome?
Carcinoid syndrome is not the tumor itself but the set of symptoms produced by what it releases: flushing of the face and neck, watery diarrhea, wheezing, and over years a thickening of the heart valves on the right side. Only a minority of people with these tumors ever develop it, and the reason is the liver. Substances such as serotonin leaving a bowel tumor travel first to the liver, which breaks them down before they reach the rest of the body. Once deposits have grown inside the liver, or where the tumor lies outside that drainage as in the lung, those substances enter the general circulation and the syndrome appears.
Also known as
Used in a sentence
A carcinoid was identified incidentally in the resected appendix.
Good to know
Carcinoid tumors are malignant despite a name suggesting otherwise, and carcinoid syndrome generally indicates either spread to the liver or a tumor sitting outside the circulation the liver filters.
Word origin
Where “carcinoid” comes from
The name joins the Greek karkinos, a crab and hence a cancer, with the suffix -oid from eidos, meaning form, giving a growth that resembles a carcinoma.