polyp

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Related to adenomatous polyp: sessile polyp, hyperplastic polyp

polyp,

in medicine, a benign tumor occurring in areas lined with mucous membrane such as the nose, gastrointestinal tract (especially the colon), and the uterus. Some polyps are pedunculated tumors, i.e., they grow on stems; others, attached by a broad base, are called sessile. Nasal polyps are usually associated with an allergic condition; since they interfere with breathing, it is advisable that they be removed. Uterine and gastrointestinal polyps are likely to cause bleeding, but, more important, they may undergo malignant degeneration and for this reason are also usually removed.

Polyp

 

a morbid growth that develops on mucosa of the respiratory tract, uterus, stomach, large intestine, rectum, and urinary bladder. Polyps are villous formations of various shapes; sometimes pear-shaped, they are usually broad-based or pedunculated. They may ulcerate and cause hemorrhages. Modern medical practice considers polyps precancerous, and therefore they are surgically removed.


Polyp

 

the common name for the predominantly benthic form of coelenterates. In metagenetic forms, that is, in hydrozoans (except hydras) and scyphozoans, polyps are capable only of vegetative reproduction, forming either medusae (in hydrozoans by budding, in scyphozoans by transverse division) or other polyps. Sexual reproduction is characteristic in such forms only in individuals of the medusa phase—free-swimming individuals or individuals remaining attached to the polyp. In homogenetic forms (hydrida and anthozoans), the polyps are capable of both sexual and vegetative reproduction. With sexual reproduction, larvae develop from the eggs and are transformed into polyps.

Polyps usually are cylindrical and measure from several millimeters to several centimeters tall (rarely up to 1 m). The upper part of the body contains the mouth, which is surrounded by tentacles. The base serves as a foot by which the polyp attaches itself to the substrate (in solitary forms) or to the colony (in colonial forms). There is often a hard external or internal skeleton of organic matter or limestone. The nervous system, which is developed considerably less than in the medusa, is in the form of a subepithelial nerve ganglion. Sex glands are present only in homogenetic forms and are located in the ectoderm (in Hydrida) or in the entoderm (in anthozoans). Sexual products are eliminated through ruptures in the walls of the gonads. In rare cases (in some actiniae), development occurs in the gastral cavity of the maternal body.

Polyps, except for hydras and a few related forms, are marine organisms. The majority lead a sedentary life; many form colonies. Movements are limited by the extension and contraction of the body and tentacles. Some solitary forms, hydras and actiniae, move slowly along the substrate; a few actiniae inhabit the depths. Polyps feed predominantly on animal substances, usually capturing their prey with their tentacles.

REFERENCES

See references under COELENTERATA.

D. V. NAUMOV

polyp

[′päl·əp]
(invertebrate zoology)
A sessile cnidarian individual having a hollow, somewhat cylindrical body, attached at one end, with a mouth surrounded by tentacles at the free end; may be solitary (hydra) or colonial (coral).
(medicine)
A smooth, rounded or oval mass projecting from a membrane-covered surface.

polyp

1. Zoology one of the two forms of individual that occur in coelenterates. It usually has a hollow cylindrical body with a ring of tentacles around the mouth
2. Pathol a small vascularized growth arising from the surface of a mucous membrane, having a rounded base or a stalklike projection
References in periodicals archive ?
While 7 (2%) patients were diagnosed with adenomatous polyps, two were diagnosed with low grade dysplasia.
[6] It is generally accepted that 95% colorectal cancers arise from benign, neoplastic adenomatous polyps (adenomas).
The commonest colon polyp type was adenomatous polyp. Screening programmes, such as stool occult blood testing and colonoscopies, especially in people over the age of 50 years, are recommended.
Colorectal cancer develops from non-cancer polyps called adenomatous polyps. A polyp is a grape-like growth on the inside wall of the colon or rectum.
found three adenomatous polyps in a cohort of 106 IBD patients (2.8%) compared to 67 in 749 non-IBD control patients (8.9%) [17].
Hindgut lesions exhibited a wide spectrum of histopathological features, adenomatous polyp and well differentiated adenocarcinoma being most common among benign and malignant lesions.
Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps 2008: A joint guideline from the American Cancer Society, the US Multi-Society task force on colorectal cancer, and the American College of Radiology.
Composite data from the international Prevention of Spontaneous Adenomatous Polyps (PreSAP) study and the Adenoma Prevention with Celecoxib (APC) trial revealed nearly a twofold risk in cardiovascular events in patients taking celecoxib at doses of 200 mg or 400 mg twice daily or 400 mg once daily, compared with patients assigned to placebo in the trials.
The greatest variation is in sensitivity for CRC, or the ability to not miss an adenomatous polyp or cancer when present.
"If you take people with colon cancer or adenomatous polyps and remove the cancer or polyp, their colons are still abnormal," says Mason.
Mixed hyperplastic adenomatous polyps--an underdiagnosed entity: report of a case of adenocarcinoma arising within a mixed hyperplastic adenomatous polyp. Am J Surg Pathol.
The review of literature showed only one case of solitary villo adenomatous polyp with malignant transformation and metastatic spread (1) and dysplasia has also been observed in a solitary polyp.