Intestinal Polypoid Adenomas Workup

  • Author: Alan BR Thomson, MD; Chief Editor: Julian Katz, MD   more...
 
Updated: Jan 5, 2012
 

Laboratory Studies

  • Fecal occult blood test (FOBT): A small proportion of large adenomas may bleed intermittently. Depending on the age of the patients tested, 10-40% of asymptomatic patients with a positive result on a fecal occult blood test have an adenoma. Quantitative testing of stool for blood has been tried, but it does not appear to have a role in screening or diagnosis of colonic adenomas at this time. Newer immunologically based tests designed to detect only human blood in stool are becoming available and are expected to increase the specificity of the test. Three fresh separate nonhydrated stools are used.
  • Stool testing for genetic alterations: Stool testing for genetic alterations that occur in adenomas is being studied. Thus far, the stool tests are more sensitive for cancers and advanced adenomas than for small tubular adenomas; these tests are expensive and may not yet be widely available.
  • CBC count: Patients with an adenoma occasionally can present with a microcytic (iron deficiency) anemia due to chronic blood loss.
  • Iron studies: Low serum iron and ferritin and an increased total iron-binding capacity (TIBC) can be observed because of blood loss in some patients with colonic adenomas and carcinomas.
  • Although guaiac-based fecal occult blood tests (GFOBTs) for CRC screening have been shown to save lives, FOBT have the disadvantage of low sensitivity for detecting advanced adenomas. Those persons with diverticular disease, hyperplastic polyps, and low-risk adenoma do not significantly different results on testing with GFOBT.
  • Adenoma patients have elevated fecal hemoglobin (Hb) which increases with advanced histology, size, pedunculated shape, and multiplicity of polyps. At a threshold of 50 ng Hb/mL, sensitivity and specificity of FOBT for advanced adenomas were 88% for 3 positive FOBT tests. It is important to define ideal thresholds for hemoglobin concentration that will give optimal sensitivity and specificity to detect advanced adenomas, as these determine the number of colonoscopies needed for positive tests (NNS, number needed to scope [ie, to find a CRC or advanced adenoma]).
  • It is important to establish the relationship between a given quantity of hemoglobin detected in the stools and the pathology detected on colonoscopy in those with positive tests.
  • In CRC screening, different positivity thresholds need to be established for the immunochemical-based screening strategies. Depending upon the threshold in terms of the amount of blood detected, there are variable rates of adenoma detection but not CRC detection. The positivity threshold will influence the NNS (number needed to scope) to find a CRC or advanced adenoma by colonoscopy in an individual testing positive by fecal immunochemical tests (FITs).
  • Fecal immunochemical tests for human hemoglobin represent a major advance in CRC screening, because they detect hemoglobin in stool samples rather than detecting just heme, as is the case with GFOBTs. Immunochemical fecal occult blood tests have been shown to have a greater sensitivity than GFOBT.
  • There are large differences in the diagnostic performance among various FITs, and the different test variances need to be carefully evaluated.
  • FITs increase the detection rates of advanced adenoma and CRC without generating an unacceptable number of false-positives, which would lead to unnecessary colonoscopies.
  • A large, Dutch, population-based, randomized controlled trial has shown that FIT detected 2.5 times as many advance adenomas and CRC as does GFOBT, despite similar colonoscopy detection rates. Thus, FIT appears to be closely superior to GFOBT for CRC screening.
  • Fecal calprotectin and tumor M2-PK protein detection in stool may have better performance characteristics than GFOBTs, but these newer tests also suffer from low sensitivity and poor specificity.
  • The analysis of fecal DNA represents an emerging new area for early detection and gives a 62-91% sensitivity for CRC and a 26-73% sensitivity for adenomas, with a specificity ranging from 93% to 100%. The major drawback of current fecal DNA testing is the unacceptable high cost.
  • "Info card" collection systems are becoming available for fecal immunochemical tests, as well as for fecal occult blood tests.
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Imaging Studies

  • Barium enema (BE) imaging of the colon can detect polyps, but they are usually found when the test is ordered for another indication. Air contrast barium enema (ACBE) is more sensitive than single contrast technique for detection of polyps. BE is included as an acceptable screening or surveillance test for colorectal cancer in the recommendations of the American Cancer Society and other organizations, but prospective controlled studies of its use in a screening program are lacking. BE is generally regarded as less sensitive than colonoscopy in detecting adenomas less than 1 cm in size, and some studies indicate that it is not as accurate as colonoscopy for even larger lesions. As a result, BE is usually considered an alternative to colonoscopy for evaluation of the entire colon.
  • CT or magnetic resonance (MR) CT colonography (virtual colonoscopy) is being evaluated for the detection of adenomas and carcinomas of the colon.[1, 2] Thus far, virtual colonoscopy has lower sensitivity than optical colonoscopy for small (< 1 cm) adenomas and has a false-positive rate, but the technology is improving rapidly and may soon be the test of choice for screening purposes, with optical colonoscopy only being performed to obtain biopsy samples and to remove clinically significant lesions identified on CT colonoscopy. Procedure volume and attenuation thresholds may be important with MRCT computer-aided polyp detection. The advantages of virtual colonoscopy include the lack of need for sedation, the short commitment of time for the test, and the potential of the patient not needing to take a cathartic bowel preparation.
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Other Tests

  • New stool screening technology aimed at detecting some of the more common genetic alterations found in adenomas is being investigated. Currently, the stool DNA testing is more sensitive for colon cancers and advanced adenomas than for small tubular adenomas.
  • Biomarkers for the detection of advanced neoplasia are not yet ready for prime time, such as measurement of the urinary metabolite of prostaglandin E2.
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Procedures

  • Colonoscopic screening for colorectal cancer and adenomas is generally recommended for high-risk individuals, such as those with 2 or more first-degree relatives with colorectal cancer or those with a single first-degree relative with colorectal cancer occurring at a young age (ie, < 50 y).
    • Enthusiasm in the gastroenterology community is increasing for offering colonoscopy screening to average-risk persons (age 50 y or older) and to high-risk persons, such as those with a family history, especially if the relative was younger than 50 years. Medicare has recently added colorectal screening using colonoscopy every 10 years as a covered benefit for average-risk individuals. The entire colon can be visualized using colonoscopy, and mortality rates related to colorectal cancer could be reduced by up to 80% by the routine use of colonoscopic screening and removal of adenomas.
    • Widespread colonoscopic screening would be expensive, and the compliance rate for such a screening program is not known. In some countries, the number of trained endoscopists is insufficient to perform colonoscopy screening in the average-risk population. With the promise of newer equipment to facilitate colonoscopy, more primary care physicians[3] and nurse endoscopists[4] may assist in the screening process.
  • Colonoscopic polypectomy is the procedure of choice for treatment of colonic adenomas, and colonoscopy is usually recommended for continued surveillance of patients with previously removed adenomas.[5] The National Polyp Study showed that regular surveillance colonoscopy with polypectomy decreased the incidence of colorectal cancer by 76-90% compared with 3 historical control groups.
  • Adequate bowel cleansing is necessary before many procedures. Several preparations are marketed for bowel cleansing (eg, polyethylene glycol 3350 [GoLYTELY, NuLYTELY], magnesium citrate [Citroma], senna [X-Prep]) in preparing patients for surgery or gastrointestinal procedures, such as endoscopy, colonoscopy, and barium x-ray studies. Bowel cleansing preparations may be used with various dietary preparations (eg, clear liquid diet 1-2 d before surgery or procedure) and are convenient to administer on an outpatient basis.
    • Guidelines vary about screening for colorectal cancer. Flexible sigmoidoscopy can be used to visualize the left colon, where about half of all colonic adenomas and cancers are located. It is more available and less expensive, and it has a lower risk than colonoscopy. Flexible sigmoidoscopy screening of the average-risk population older than 50 years could decrease the colorectal cancer mortality rate by about 40-50% and incidence by 30-40%. If an adenoma is found on sigmoidoscopy, colonoscopy should then be performed.
  • Performing sigmoidoscopy for the detection of advanced adenomas and CRC has been likened to undertaking mammography on only one breast. Nonetheless, performing screening sigmoidoscopy every 5 years has been shown to save lives, presumably by finding left-sided lesions.
  • The answer to the limited number of individuals capable of performing quality colonoscopies may be addressed by training family physicians and nurse practitioners to undertake screening colonoscopies rather than screening sigmoidoscopies.
  • An analysis of 12 studies of colonoscopies performed by primary care physicians on 18, 292 patients demonstrated that at one point in time the mean adenoma detection rate was 28.9% and the CRC detection rate was 1.7%. These are similar rates as those reported by experienced specialists.
  • In studies of family physicians and other practitioners performing screening colonoscopy, the cecal intubation rate was 89.2%, and the major implication rate was only 0.04% (40/105). These indicators are comparable to those recommended by the American Society for Gastrointestinal Endoscopy, the American College of Gastroenterology, the Society of American Gastrointestinal Endoscopic Surgeon.
  • Another approach to provide a means for more persons to have CRC screening is for people to have a screening sigmoidoscopy, and depending on the results of the sigmoidoscopy, to use the results of findings from the distal colon to provide risk stratification for the need for complete colonoscopy. However, this alternative has a low ability to predict the presence of advanced proximal lesions in the colon from the findings in the distal colon, which endangers the aim of such a program. For example, in a group of patients with advanced proximal lesions, only 50% had distal polyps. Thus, basing the decision to do total colonoscopy on the findings of sigmoidoscopy would be unsafe.

Optical colonoscopy (OC)

  • Prospective studies have been reported comparing the performance characteristics of FOBT, FIT, flexible sigmoidoscopy (FS), optical colonoscopy (OC) (also known as white light colonoscopy [WLC]), and CT colonography (CTC) for the detection of advanced adenomas and CRC. Sensitivities for detecting advanced colonic neoplasia were as follows: 20% for FOBT, 32% for FIT, 83.3% for FS, 100% for OC and 96.7% for CTC. High-resolution and low-dose CTC reach a sensitivity comparable with OC for polyps larger than 5 mm. Although patients must be provided information about all testing choices, clearly FOBT and FIT are much inferior to FS, OC, and CTC for the detection of advanced adenomas.
  • In an average risk population, CTC approximates OC, the so-called "gold standard" for screening for CRC.
  • Risk rates for colonoscopic screening in high-skill centers have been reported, but in usual clinical practice the pooled rate of colonoscopy-related bleeding was 164 per 1000, and for perforation, it was 85 per 1000; the death rate was 7.4 per 1000. Per colonoscopy, this represents a 1/610 risk for bleeding, 1/1,176 risk for perforation, and 1/14,000 risk for death
  • Although OC is considered to be the "gold standard" for screening for CRC by looking for adenomatous polyps, it is recognized that the "miss rate" for advanced adenomas and CRC with OC is sufficiently high to be of concern.
  • There is a wide variation in the achievement among endoscopy units and among endoscopists of the quality standards of OCs.[6, 7] For example, even at a center of excellence at the Indiana University School of Medicine, detection of nonadenomatous polyps by individual endoscopists at OC is highly variable, and this correlates with an increased removal rate of adenomatous polyps.
  • In usual clinical practice, the use of sedation/analgesia, the colon-cleansing quality, the endoscopist, the OC volume, and the load and organizational complexity of the OC center influence the quality of the OC.
  • An OC withdrawal time from the cecum of 8 minutes will yield higher detection rates for any neoplasia or advanced neoplasia, as compared with detection rates of less than 8 minutes.
  • Adequate colon cleansing is the most frequent problem to achieve the standards of high OC performance.
  • Administration of single-dose lubiprostone before split-dose polyethylene glycol electrolyte bowel preparation without dietary restriction improves colonic mucosal visualization during OC, and it is well tolerated by patients.[8]
  • Competence success rates of OC are evaluated on the basis of procedure completion rate and cecal intubations time: success increased from 72% after the first colonoscopy to 83% after the first 100 procedures, 91% after 150 procedures, and 99% after 300 procedures. Basic competence in technically efficient screening and diagnostic OC generally requires experience with more than 150 cases.

Beyond white-light optical colonoscopy (WLC)

  • In order to improve the performance characteristics of the usual optical colonoscopy WLC, a variety of new endoscopic techniques have been developed such as: autofluorescence imaging (AFI), wide-angle colonoscopy (WAC), endoscopic trimodel imaging (ETMI) (incorporating AFI plus high-resolution endoscopy [HRE]), the Third Eye Retroscope and narrow band imaging (NBI), confocal laser endomicroscopy (CLE), confocal fluorescent microscopy (CFM), chromoendoscopy, as well as 4-dimensional (4-D) elastically scattered light fingerprinting for the detection of an early increase in blood supply (EIBS) in the colon.
  • Unfortunately, the results of wide-angle endoscopes have been disappointing.

Chromoendoscopy

  • Chromoendoscopy and methylene blue, with or without the use of a magnifying endoscope, is being used in some centers to improve the accuracy of diagnosing colonic polyps and to identify small adenomas and aberrant crypt foci. The surface architecture of adenomas (ie, brainlike appearance with gyri) is different from that of hyperplastic polyps (ie, chickenwire fencelike). Thus, magnifying chromoendoscopy can potentially be used to distinguish these 2 types of colonic polyps.
  • Chromoendoscopy may be one way of enhancing the ability for the colonoscopist to detect colon polyps, particularly diminutive, flat lesions that may be otherwise difficult to detect.
  • The improved sensitivity of chromoendoscopy over OC/WLC has been confirmed in European and Asian centers, as well as from the Mount Sinai Hospital in New York City.
  • Colonoscopic surveillance of patients with chronic colitis, using methylene blue dye-spray targeted biopsies, results in improved dysplasia yield as well as lesions in the cecum and ascending colon, as compared with OC and random biopsies.
  • Chromoendoscopy yields significantly more patients with at least one neoplastic lesion (OR, 1.61), and significantly more patients with 3 or more neoplastic lesions (OR, 2.55).
  • Chromoendoscopy finds additional adenomas (44%) in more subjects than does routine colonoscopy plus intensive inspection (17%), and identifies significantly more missed adenomas per subject (0.7 vs 0.2, respectively). The missed adenomas may be smaller and they are more often right-sided.
  • An atlas has been developed to demonstrate typical endoscopic findings by conventional endoscopy and chromoendoscopy.[9]
  • Nonwhite-light optics such as NBI enhance image contrast in short wavelength light. This falls within the hemoglobin absorption band, facilitating clear visualization of vascular structures and allowing analysis of the "pit-pattern" of the epithelium. However, a randomized controlled trial from Stanford University did not demonstrate any superiority of NBI versus OC/WLC in terms of missed detection rates of CRC.[10]
  • NBI without optical magnification provides high-confidence predictions of adenoma versus hyperplastic polyp histology. NBI with magnification has a sensitivity of 90.5% and a specificity of 89.2% for the differentiation of neoplastic versus non-neoplastic colonic lesions, without the necessity of using dye.
  • The NBI pit-pattern and vascular pattern intensity show good agreement for the detection of dysplasia in polyps < 10 mm in size.
  • However, a large randomized trial in a homogeneous private practice setting in Berlin did not show any objective advantage of the NBI technique over white-light high-definition television imaging, in terms of improved adenoma detection rate.
  • Aberrant crypt foci (ACF) may be precursors to colorectal adenomas, and they may be potential biomarkers for CRC.[11, 12] Although chromoendoscopy with magnification colonoscopy can identify ACF in vivo, the definition for ACF and a technique for endoscopic identification and classification is required before ACF can be used as a biomarkers for CRC.
  • Crypt morphologic patterns correlate with the histopathologic diagnosis. Endoscopic techniques such as high-magnification chromoendoscopy and endoscopic optical coherent tomography are capable of visualizing crypt morphology in vivo, but the clinical utility of this has yet to be proven.

Confocal laser endomicroscopy [13, 14]

  • Confocal laser endomicroscopy (CLM) is an in vivo method to help localize intraepithelial neoplasia by way of "virtual biopsies" and allows targeting normal biopsies for histologic assessment.
  • CLM provides a 4-fold higher diagnostic yield relative to white-light endoscopy with random biopsies. CLM be used may in the future in conjunction with fluorescent peptide markers to target neoplasia even further, in order to provide in vivo histopathology and a marker for targeted biopsying.

Autofluorescent endoscopy

  • Autofluorescent endoscopy (AFE) has been developed to enhance OC in the diagnosis of colonic lesions. AFE detects more polyps in the right side of the colon compared with OC/WLC, which may provide a diagnostic advantage.[15] AFE also has a high sensitivity and specificity at distinguishing adenomatous from hyperplasic polyps.[16] Unfortunately, even with AFE and with high-resolution endoscopy (HRE), adenoma miss rates are greater than 20%, AFE does not significantly reduce the adenoma miss rate as compared with HRE.
  • Fluoro-2-droxy-D:-glucose positron emission tomography (FDG-PET) is under study.

CT colonography (CTC); computer-associated diagnosis (CAD), Fujinon Intelligent Color Enhancement (FICE) imaging

  • CTC is a noninvasive alternative for CRC screening, which does not have the risk of colonic perforation, may have a higher patient preference, and may avoid the need for preprocedure purgation. CTC is a rapidly evolving technology, and consensus guidelines suggest that CTC must be offered to patients as one of the valid options to CRC screening, together with FOBT, FIT, FS, and OC. For detecting polyps larger than 10 mm, CTC has a sensitivity per patient of 91% and a specificity per patient of 99.2%. This is comparable to UC.
  • CTC may also be useful to identify carcinomas proximal to a stenosing lesion, to detect extracolonic malignancies, and may become a useful technique for the evaluation of the nonvisualized part of the colon after incomplete OC/WLC. CTC with the Fujinon intelligent Color Enhancement (FICE) system is a new dyeless imaging technique. The adenoma detection rates with CTC plus FICE are comparable to OC chromoendoscopy with indigocarmine spraying.
  • Meta-analysis has demonstrated that CTC is superior to double-contrast barium enema (DCBE) in terms of its sensitivity and specificity for detecting colorectal polyps 6 mm or larger. CTC may substitute for DCBE or CRC/polyp screening, and this is reflected in some recent guidelines on CRC screening.
  • CTC may be improved further through the use of computer-aided detection (CAD). The use of CTC plus CAD increases the sensitivity for detecting polyps in the 6 mm or larger polyp size range. Enhancing level sets have been added to CAD to further increase the sensitivity for the detection of small polyps. CTC plus CAD does not adversely influence the correct classification or diagnostic confidence findings.
  • Although CTC plus CAD increase the effectiveness for the detection of morphologically flat cancer, minimally raised laterally spreading tumors remain a detection problem. Any CRC/polyp screening method that would decrease the requirement for cathartic bowel preparation might improve patient adherence to the recommendations for CRC screening.[17] Electronic cleansing is an emerging method for segmentation of fecal material in CTC.
  • The structure/analysis cleansing has been developed as an electronic cleansing method, and provides a cleansed colon with substantially reduced subtraction artifacts. Labeling the stool with high-contrast agents may replace the use of laxatives in CTC. The automatic detection of colonic polyps using a CTC plus CAD system on cathartic-free data improve an approximately 74-86% true positive with the addition of an automatic stool removal module. Fecal tagging to provide for CTC without cathartic preparation is technically feasible, safe, and may have a special role to play in the study of the elderly, or in those hesitant to undergo OC because of the requirement for purgation.
  • In the context of a screening program for CRC based on FOBT, CTC shows high per segment and per lesion cause a predictor value for colonic masses and polyps greater than 9 mm, and therefore CTC has the potential to become a useful technique for evaluation of the nonvisualized part of the colon after incomplete OC.

Follow-up

  • Among persons with no colorectal neoplasia on initial screening OC, the 5-year risk of CRC is extremely low, as also is the risk of advanced adenoma.[18] These US data supports a rescreening (surveillance) interval of 5 years or longer after a normal OC examination.
  • A 3-year follow-up OC is recommended for persons with adenomatous polyps 1 cm or larger.
  • A study by Shin et al demonstrated a relationship between CRC risk and carcinogen exposure from meat, heterocyclic amine exposure, and metabolizing enzyme polymorphism.[19]
  • Persons with colonic adenomas with advanced pathology at baseline have a significantly higher risk for metachronous adenomas of advanced pathology. Their first surveillance colonoscopy after the initial screening procedure should be moved forward from 5 to 3 years.
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Histologic Findings

Adenomas are classified based on their size, architecture, and degree of dysplasia. Large size, villous content, and distal location are associated with severe dysplasia in colorectal adenomas.

  • Size: Most adenomas are small (< 1 cm). Large adenomas (>1 cm) tend toward more severe dysplasia and more worrisome architecture, and the risk of malignant potential is increased. However, small (5-10 mm) adenomas as well as diminutive adenomas (< 4 mm) may have advanced histology, including carcinoma, in 10.1% and 1.7%, respectively. The term advanced adenoma is used for adenomas that are 1 cm or larger in diameter or that have tubulovillous or villous histologic features or high-grade dysplasia.
    • The presence of 3 or more small adenomas or the presence of 1 or more advanced adenomas is associated with a 2- to 3-fold increased risk of metachronous adenomas.
    • Other features that may increase the risk of metachronous adenomas or colorectal cancer include an adenoma located proximal to the splenic flexure, male gender, older age, or a first-degree relative with colorectal cancer.
  • Architecture: Traditionally, adenomas are described as tubular, tubulovillous, or villous, primarily based on the overall percentage of villous component. Risk of malignancy increases with increased villous composition of the polyp.
    • Tubular adenomas are variously defined as those that contain 0-25% villous tissue. About 70-85% of all adenomas are tubular; they tend to be smaller than villous adenomas. See the image below. Intestinal polypoid adenomas. Tubular adenoma, lowIntestinal polypoid adenomas. Tubular adenoma, low-power view. Courtesy of G. Warren, MD, Rose Medical Center, Denver, Colo.
    • Tubulovillous adenomas contain approximately 25-75% villous tissue. These adenomas represent 10-25% of all adenomas; they tend to be intermediate in size.
    • Villous adenomas contain more than 75% villous tissue. These adenomas represent 5% of all adenomas; they tend to be larger and have the greatest malignancy potential. See the image below. Intestinal polypoid adenomas. Villous adenoma, lowIntestinal polypoid adenomas. Villous adenoma, low-power view. Courtesy of G. Warren, MD, Rose Medical Center, Denver, Colo.
    • Two other architectural types exist as well.
      • Flat types are primarily in familial groups. They are not raised and are usually small erythematous plaques that are multiple, often have multiple foci of high-grade dysplasia, and can be associated with small adenocarcinomas.
      • Hyperplastic polyps
        • The hyperplasic polyp-serrated adenoma-adenoma carcinoma pathway is acknowledged. Serrated adenomatous polyps (SA) show microsatellite instability and deficiency in DNA mismatch repair.[20] The sessile serrated adenoma is a larger polyp, sessile, more often found on the right side of the colon, and likely represents an intermediate form between the hyperplastic polyp and the sessile adenoma. Colonoscopic surveillance of sessile serrated adenomas is appropriate.
        • Mixed hyperplastic (serrated) types make up less than 1% of all polyps. They have hyperplastic architecture with evidence of dysplasia and are associated with high frequency of high-grade dysplasia.
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Staging

Dysplasia is a neoplastic change in histology. All adenomas are dysplastic; they display degrees of hyperchromasia, nucleolar prominence, nuclear pleomorphism, and increased mitoses. Dysplasias are classified as either low-grade or high-grade. Invasive carcinoma is distinguished from dysplasia by invasion of neoplastic tissue beyond the muscularis mucosa.

  • Low-grade - Basal or stratified nuclei, crowded glands, less goblet cells and mucin
  • High-grade - Loss of glandular architecture, increased mitoses (includes previously termed carcinoma in situ and intramucosal carcinoma)

Sporadic adenoma in patients with ulcerative colitis is diagnosed only when the lesion is located proximal to the ulcerative colitis in an endoscopically and histologically normal mucosa. Otherwise, if the adenoma occurs in an area marked by ulcerated colitis, proctocolectomy is recommended.

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Contributor Information and Disclosures
Author

Alan BR Thomson, MD  Professor of Medicine, Division of Gastroenterology, University of Alberta, Canada

Alan BR Thomson, MD is a member of the following medical societies: Alberta Medical Association, American College of Gastroenterology, American Gastroenterological Association, Canadian Association of Gastroenterology, Canadian Medical Association, College of Physicians and Surgeons of Alberta, and Royal College of Physicians and Surgeons of Canada

Disclosure: Nothing to disclose.

Coauthor(s)

Dennis J Ahnen, MD  Staff Physician, Denver VA Medical Center and Professor of Medicine, University of Colorado Denver School of Medicine

Dennis J Ahnen, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Physicians, American Federation for Medical Research, American Gastroenterological Association, Crohns and Colitis Foundation of America, and Gastroenterology Research Group

Disclosure: EXACT Sciences travel expenses Review panel membership

Specialty Editor Board

Rajeev Vasudeva, MD, FACG  Clinical Professor of Medicine, Consultants in Gastroenterology, University of South Carolina School of Medicine

Rajeev Vasudeva, MD, FACG is a member of the following medical societies: American College of Gastroenterology, American Gastroenterological Association, American Society for Gastrointestinal Endoscopy, Columbia Medical Society, South Carolina Gastroenterology Association, and South Carolina Medical Association

Disclosure: Pricara Honoraria Speaking and teaching; UCB Consulting fee Consulting

Francisco Talavera, PharmD, PhD  Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

Douglas M Heuman, MD, FACP, FACG, AGAF  Chief of GI, Hepatology, and Nutrition at North Shore University Hospital/Long Island Jewish Medical Center; Professor, Department of Medicine, Hofstra North Shore-LIJ School of Medicine

Douglas M Heuman, MD, FACP, FACG, AGAF is a member of the following medical societies: American Association for the Study of Liver Diseases, American College of Physicians, and American Gastroenterological Association

Disclosure: Novartis Grant/research funds Other; Bayer Grant/research funds Other; Otsuka Grant/research funds None; Bristol Myers Squibb Grant/research funds Other; Scynexis None None; Salix Grant/research funds Other; MannKind Other

Alex J Mechaber, MD, FACP  Senior Associate Dean for Undergraduate Medical Education, Associate Professor of Medicine, University of Miami Miller School of Medicine

Alex J Mechaber, MD, FACP is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians-American Society of Internal Medicine, and Society of General Internal Medicine

Disclosure: Nothing to disclose.

Chief Editor

Julian Katz, MD  Clinical Professor of Medicine, Drexel University College of Medicine

Julian Katz, MD is a member of the following medical societies: American College of Gastroenterology, American College of Physicians, American Gastroenterological Association, American Geriatrics Society, American Medical Association, American Society for Gastrointestinal Endoscopy, American Society of Law, Medicine & Ethics, American Trauma Society, Association of American Medical Colleges, and Physicians for Social Responsibility

Disclosure: Nothing to disclose.

Additional Contributors

The authors and editors of eMedicine gratefully acknowledge the contributions of previous coauthor, John Riopelle, DO, to the development and writing of this article.

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Intestinal polypoid adenomas. Endoscopic view of pedunculated polyp.
Intestinal polypoid adenomas. Endoscopic view of sessile polyp.
Intestinal polypoid adenomas. Tubular adenoma, low-power view. Courtesy of G. Warren, MD, Rose Medical Center, Denver, Colo.
Intestinal polypoid adenomas. Villous adenoma, low-power view. Courtesy of G. Warren, MD, Rose Medical Center, Denver, Colo.
Intestinal polypoid adenomas. High-power view of adenomatous polyp with low-grade dysplasia. Courtesy of G. Warren, MD, Rose Medical Center, Denver, Colo.
Intestinal polypoid adenomas. Villous adenoma with grade IV invasive carcinoma. Courtesy of G. Warren, Rose Medical Center, Denver, Colo.
 
 
 
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