anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its ...

, a polyp is an abnormal growth of tissue projecting from a

mucous membrane A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It i ...

. If it is attached to the surface by a narrow elongated

stalk Stalk or stalking may refer to: Behaviour * Stalk, the stealthy approach (phase) of a predator towards its prey * Stalking, an act of intrusive behaviour or unwanted attention towards a person * Deer stalking, the pursuit of deer for sport Biol ...

, it is said to be ''pedunculated''; if it is attached without a stalk, it is said to be ''sessile''. Polyps are commonly found in the colon,

stomach The stomach is a muscular, hollow organ in the gastrointestinal tract of humans and many other animals, including several invertebrates. The stomach has a dilated structure and functions as a vital organ in the digestive system. The stomach i ...

nose A nose is a protuberance in vertebrates that houses the nostrils, or nares, which receive and expel air for respiration alongside the mouth. Behind the nose are the olfactory mucosa and the sinuses. Behind the nasal cavity, air next pass ...

, ear, sinus(es),

urinary bladder The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine enters ...

, and

uterus The uterus (from Latin ''uterus'', plural ''uteri'') or womb () is the organ in the reproductive system of most female mammals, including humans that accommodates the embryonic and fetal development of one or more embryos until birth. The ...

. They may also occur elsewhere in the body where there are mucous membranes, including the

cervix The cervix or cervix uteri (Latin, 'neck of the uterus') is the lower part of the uterus (womb) in the human female reproductive system. The cervix is usually 2 to 3 cm long (~1 inch) and roughly cylindrical in shape, which changes durin ...

vocal folds In humans, vocal cords, also known as vocal folds or voice reeds, are folds of throat tissues that are key in creating sounds through vocalization. The size of vocal cords affects the pitch of voice. Open when breathing and vibrating for speech ...

, and

small intestine The small intestine or small bowel is an organ in the gastrointestinal tract where most of the absorption of nutrients from food takes place. It lies between the stomach and large intestine, and receives bile and pancreatic juice through t ...

. Some polyps are tumors (

neoplasm A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

s) and others are non-neoplastic, for example hyperplastic or

dysplastic Dysplasia is any of various types of abnormal growth or development of cells (microscopic scale) or organs (macroscopic scale), and the abnormal histology or anatomical structure(s) resulting from such growth. Dysplasias on a mainly microscopic ...

, which are benign. The neoplastic ones are usually benign, although some can be pre-malignant, or concurrent with a malignancy. The name is of ancient origin, in use in English from about 1400 for a nasal polyp, from Latin ''polypus'' through Greek. The animal of similar appearance called polyp is attested from 1742, although the word was earlier used for an octopus.

Digestive polyps

Relative incidences by location: File:Pie chart of colorectal polyp etiologies.png, Incidences and malignancy risks of various types of colorectal polyps. File:Pie chart of relative incidences of gastric polyps.png, Relative incidences of gastric polyps.

Colorectal polyp

While colon polyps are not commonly associated with symptoms, occasionally they may cause rectal bleeding, and on rare occasions

pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...

diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin ...

constipation Constipation is a bowel dysfunction that makes bowel movements infrequent or hard to pass. The stool is often hard and dry. Other symptoms may include abdominal pain, bloating, and feeling as if one has not completely passed the bowel moveme ...

. They are a concern because of the potential for

colon cancer Colorectal cancer (CRC), also known as bowel cancer, colon cancer, or rectal cancer, is the development of cancer from the colon or rectum (parts of the large intestine). Signs and symptoms may include blood in the stool, a change in bowel ...

being present microscopically, and the risk of benign colon polyps becoming

malignant Malignancy () is the tendency of a medical condition to become progressively worse. Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...

over time. Since most polyps are

asymptomatic In medicine, any disease is classified asymptomatic if a patient tests as carrier for a disease or infection but experiences no symptoms. Whenever a medical condition fails to show noticeable symptoms after a diagnosis it might be considered as ...

, they are usually discovered at the time of colon cancer screening. Common screening methods are occult blood test, colonoscopy with a modern flexible endoscope, sigmoidoscopy (usually with the older rigid endoscope), lower gastrointestinal series (barium enema),

digital rectal examination Digital rectal examination (DRE; la, palpatio per anum, PPA) is an internal examination of the rectum, performed by a healthcare provider. Prior to a 2018 report from the U.S. Preventive Services Task Force, the DRE was a common and "dreaded" co ...

(DRE), virtual colonoscopy or Cologuard. The polyps are routinely removed at the time of colonoscopy, either with a wire loop known as a polypectomy snare (first description by P. Deyhle, Germany, 1970), or with biopsy forceps. If an adenomatous polyp is found, it must be removed, since such a polyp is pre-cancerous and has a propensity to become cancerous. For certainty, all polyps which are found by any diagnostic modality, are removed by a colonoscopy. Although colon cancer is usually not found in polyps smaller than 2.5 cm, all polyps found are removed since their removal reduces the likelihood of future colon cancer. When adenomatous polyps are removed, a repeat colonoscopy is usually performed three to five years later. Most colon polyps can be categorized as sporadic.

Inherited polyposis syndromes

Familial adenomatous polyposis Familial adenomatous polyposis (FAP) is an autosomal dominant inherited condition in which numerous adenomatous polyps form mainly in the epithelium of the large intestine. While these polyps start out benign, malignant transformation into c ...

Peutz–Jeghers syndrome Peutz–Jeghers syndrome (often abbreviated PJS) is an autosomal dominant genetic disorder characterized by the development of benign hamartomatous polyps in the gastrointestinal tract and hyperpigmented macules on the lips and oral mucosa ( ...

* Turcot syndrome * Juvenile polyposis syndrome * Cowden disease *

Bannayan–Riley–Ruvalcaba syndrome Bannayan–Riley–Ruvalcaba syndrome (BRRS) is a rare overgrowth syndrome and hamartomatous disorder with occurrence of multiple subcutaneous lipomas, macrocephaly and hemangiomas. The disease is inherited in an autosomal dominant manner. The di ...

(Bannayan–Zonana syndrome) *

Gardner's syndrome Gardner's syndrome (also known as Gardner syndrome, familial polyposis of the colon, or familial colorectal polyposis) is a subtype of familial adenomatous polyposis (FAP). Gardner syndrome is an autosomal dominant form of polyposis characteriz ...

* Serrated polyposis syndrome

Non-inherited polyposis syndromes

Cronkhite–Canada syndrome Cronkhite–Canada syndrome is a rare syndrome characterized by multiple polyps of the digestive tract. It is sporadic (i.e. it does not seem to be a hereditary disease), and it is currently considered acquired and idiopathic (i.e. cause remai ...

Types of colon polyps

Malignant Malignancy () is the tendency of a medical condition to become progressively worse. Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...

* Hamartomatous * Hyperplastic * Inflammatory:

Inflammatory fibroid polyp Inflammatory fibroid polyp (IFP) is a benign abnormal growth of tissue projecting into the lumen of the gastrointestinal tract. Pathology IFPs consist of spindle cells that are concentrically arranged around blood vessels and have inflammation, ...

Adenomatous polyps

Adenomatous polyps, or adenomas, are polyps that grow on the lining of the colon and which carry a high risk of

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal bl ...

. The adenomatous polyp is considered pre-malignant, i.e., likely to develop into

. The other types of polyps that can occur in the colon are hyperplastic and inflammatory polyps, which are unlikely to develop into colorectal cancer. About 5% of people aged 60 will have at least one adenomatous polyp of 1 cm diameter or greater. Multiple adenomatous polyps often result from

familial polyposis coli Gardner's syndrome (also known as Gardner syndrome, familial polyposis of the colon, or familial colorectal polyposis) is a subtype of familial adenomatous polyposis (FAP). Gardner syndrome is an autosomal dominant form of polyposis characteri ...

familial adenomatous polyposis Familial adenomatous polyposis (FAP) is an autosomal dominant inherited condition in which numerous adenomatous polyps form mainly in the epithelium of the large intestine. While these polyps start out benign, malignant transformation into c ...

, a condition that carries a very high risk of colon cancer.

Types

Adenomas constitute approximately 10% of digestive polyps. Most polyps (approximately 90%) are small, usually less than 1 cm in diameter, and have a small potential for malignancy. The remaining 10% of adenomas are larger than 1 cm and approach a 10% chance of containing invasive cancer. There are three types of adenomat