eMedicine Specialties > Gastroenterology > Colon

Colonic Polyps: Differential Diagnoses & Workup

Author: Gregory H Enders, MD, PhD, Member, Fox Chase Cancer Center
Coauthor(s): Wafik S El-Deiry, MD, PhD, Professor of Medicine, Department of Hematology/Oncology; Co-Program Leader, Radiation Biology Program, Abramson Comprehensive Cancer Center, University of Pennsylvania School of Medicine
Contributor Information and Disclosures

Updated: Aug 22, 2008

Differential Diagnoses

Familial Adenomatous Polyposis
Gardner Syndrome
Inflammatory Bowel Disease
Peutz-Jeghers Syndrome

Other Problems to Be Considered

The differential varies, depending on the age of the patient and the presenting symptoms. A family history of polyposis is very significant because it raises the possibility of an inherited susceptibility, such as FAP or other polyposis syndromes. The differential diagnosis can be broad if the patient presents with rectal bleeding or diarrhea.

  • Sporadic polyps associated with aging
  • Benign adenoma/hyperplastic polyp
  • Pseudopolyps associated with inflammation
  • Juvenile polyposis
  • Basal cell nevus syndrome (includes basal cell carcinomas and colonic hamartomatous polyps)
  • Turcot syndrome (includes polyps, medulloblastoma, congenital hypertrophy of the retinal pigmented epithelium [CHRPE], and glioblastoma multiforme)
  • Cowden syndrome (includes polyps, fibrocystic disease, breast cancer, and thyroid cancer)
  • Hereditary nonpolyposis colorectal cancer (HNPCC)
  • Hyperplastic polyposis

Workup

Laboratory Studies

  • No laboratory test can determine definitively whether a given patient has a colonic polyp. A stool occult blood test can detect a fraction (20-40%) of colonic polyps that are greater than 10 mm in diameter but can also reflect other causes of gastrointestinal blood loss.
  • Anemia is not specific for colonic polyps but can be an indication of their presence.
  • A patient with a family history of FAP may inherit a mutation in the APC gene.
    • A blood test may detect this heterozygous state.
    • Because most APC mutations involve truncations of the protein, an in vitro protein truncation assay has been developed by Powell et al.2,3 This assay amplifies segments of APC messenger RNA (mRNA) and expresses the protein parts in vitro to readily detect the truncated products. A positive test finding only indicates susceptibility, not the actual presence of a colonic polyp.
  • Genetic testing of blood samples can also detect most cases of hereditary nonpolyposis colorectal cancer (HNPCC)/Lynch syndrome. Despite the name, patients with HNPCC have polyps but many fewer than those patients with APC syndrome.

Imaging Studies

  • Air contrast barium enema
    • This test can detect larger colonic polyps but can miss smaller ones; it has a low false-positive rate.
    • In a study, air contrast barium enema detected only about 50% of colonic polyps greater than 1 cm in diameter.
  • Virtual colonoscopy
    • This test is performed by CT scanning (or MRI) and has shown promise in research studies, detecting more than 80% of large polyps. In a large, multicenter trial, however, a disappointing sensitivity of only 55% was obtained for colonic polyps 10 mm or larger in diameter.
    • Another recent trial found a detection rate for CT scanning comparable to colonoscopy, although some methodological issues have been raised regarding this study4 Virtual colonoscopy is beginning to be performed for screening outside research settings on limited numbers of patients. A main drawback is that a second procedure, a colonoscopy, is required to remove detected colonic polyps. Whether the radiation exposure from CT scanning may be significant is debated.
    • In most methods, a thorough colon preparation is required. Methods are under development to label stool with barium meals, obviating the need for cathartic bowel prep.

Procedures

  • Adequate bowel cleansing is necessary prior to many procedures.
    • Several preparations are marketed for bowel cleansing (eg, polyethylene glycol 3350 [GoLYTELY, NuLYTELY, HalfLYTELY], magnesium citrate [Citroma], senna [X-Prep]) in preparing patients for gastrointestinal procedures, such as colonoscopy and barium x-ray studies.
    • Bowel cleansing preparations may be used with various dietary preparations (eg, clear liquid diet the day before surgery or procedure) and are convenient to administer on an outpatient basis. Nonetheless, distaste for or discomfort from the preparation remains a complaint of some patients.
  • Flexible sigmoidoscopy
    • Flexible sigmoidoscopy is a good screening test and the only procedure or imaging modality to be validated by studies that document a decrease in colorectal cancer mortality. However, this procedure does not examine the entire colon. Studies indicate that the majority of large adenomatous polyps in women will be missed by using flexible sigmoidoscopy alone.
    • Screening is usually begun at age 50 years in patients who are at average risk.
    • Randomized controlled trials have documented a reduction in mortality from colon cancer in populations screened by flexible sigmoidoscopy. However, studies suggest that about 40% of high-risk proximal adenomas remain undetected when this procedure is used as the primary screening modality.
  • Colonoscopy
    • Colonoscopy is the preferred test to detect colonic polyps, obtain biopsies, and/or perform endoscopic resection. Sensitivities for large colonic polyps in the 80-90% range have been reported.
    • Although flexible sigmoidoscopy and stool tests for occult blood have been the mainstays of screening to prevent colon cancer, some clinicians now favor colonoscopy as a primary screening tool.
    • See related CME at Colonoscopy and Colorectal Cancer Prevention.
  • Stool DNA
    • Tests have been developed that detect mutant, fragmented, and/or methylated DNA from exfoliated colon tumor cells in stool.
    • These tests have shown the ability to detect a substantial fraction of tumors in clinical trials5 but are expensive and appear to be less sensitive than colonoscopy.

Histologic Findings

Adenomatous polyps are of 3 different histological types, as follows: tubular, villous, and tubulovillous. Adenomatous polyps may show changes of dysplasia, which distinguish them from hyperplastic polyps. The most common benign polyp is hyperplastic.

Staging

Colonic polyps are typically benign. Colonic polyps that contain high-grade dysplasia or microinvasive cancer confined to the mucosa are often termed carcinoma in situ.

More on Colonic Polyps

Overview: Colonic Polyps
Differential Diagnoses & Workup: Colonic Polyps
Treatment & Medication: Colonic Polyps
Follow-up: Colonic Polyps
References
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References

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  2. Powell SM, Petersen GM, Krush AJ, Booker S, Jen J, Giardiello FM, et al. Molecular diagnosis of familial adenomatous polyposis. N Engl J Med. Dec 30 1993;329(27):1982-7. [Medline].

  3. Powell SM. Direct analysis for familial adenomatous polyposis mutations. Mol Biotechnol. Feb 2002;20(2):197-207. [Medline].

  4. Kim DH, Pickhardt PJ, Taylor AJ, et al. CT colonography versus colonoscopy for the detection of advanced neoplasia. N Engl J Med. Oct 4 2007;357(14):1403-12. [Medline].

  5. Itzkowitz SH, Jandorf L, Brand R, et al. Improved fecal DNA test for colorectal cancer screening. Clin Gastroenterol Hepatol. Jan 2007;5(1):111-7. [Medline].

  6. Beach R, Chan AO, Wu TT, et al. BRAF mutations in aberrant crypt foci and hyperplastic polyposis. Am J Pathol. Apr 2005;166(4):1069-75. [Medline].

  7. Bussey HJ, DeCosse JJ, Deschner EE, et al. A randomized trial of ascorbic acid in polyposis coli. Cancer. Oct 1 1982;50(7):1434-9. [Medline].

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  10. Cotran RS, Kumar V, Robbins SL. Tumors of the small and large intestines. In: Cotran R, Kumar V, Robbins S, eds. Pathologic Basis of Disease. 5th ed. Huntington, NY: WB Saunders Company; 1994:809-822.

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  12. Itzkowitz SH, Kim YS. Colonic polyps and polyposis syndromes. In: Feldman M, Sleisenger MH, Scharschmidt BF, eds. Sleisinger & Fordtran's Gastrointestinal and Liver Disease; Pathophysiology, Diagnosis, Management. Vol 2. 6th ed. Philadelphia, Pa: WB Saunders Company; 1998:1865-1905.

  13. Kiesslich R, Goetz M, Lammersdorf K, et al. Chromoscopy-guided endomicroscopy increases the diagnostic yield of intraepithelial neoplasia in ulcerative colitis. Gastroenterology. Mar 2007;132(3):874-82. [Medline].

  14. Kinzler KW, Vogelstein B. Lessons from hereditary colorectal cancer. Cell. Oct 18 1996;87(2):159-70. [Medline].

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  16. [Best Evidence] Logan RF, Grainge MJ, Shepherd VC, et al. Aspirin and folic acid for the prevention of recurrent colorectal adenomas. Gastroenterology. Jan 2008;134(1):29-38. [Medline].

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Further Reading

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Keywords

colonic polyps, colonic polyp, colon polyp, colon polyps, colon cancer, colon cancer polyp, colon, colonoscopy, colonoscopy polyp, polyps in colon, polyps in the colon, adenomas, hyperplastic polyps, benign epithelial neoplasms, polyposis syndromes, familial adenomatous polyposis, FAP, Gardner syndrome, Turcot syndrome, Peutz-Jeghers syndrome, Cowden disease, familial juvenile polyposis, hereditary nonpolyposis colorectal cancer, HNPCC, dysplasia-associated lesion or mass, DALM, sulindac, polypectomy, colectomy

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Contributor Information and Disclosures

Author

Gregory H Enders, MD, PhD, Member, Fox Chase Cancer Center
Gregory H Enders, MD, PhD is a member of the following medical societies: American Association for Cancer Research, American Association for the Advancement of Science, American Gastroenterological Association, American Medical Association, and Massachusetts Medical Society
Disclosure: Nothing to disclose.

Coauthor(s)

Wafik S El-Deiry, MD, PhD, Professor of Medicine, Department of Hematology/Oncology; Co-Program Leader, Radiation Biology Program, Abramson Comprehensive Cancer Center, University of Pennsylvania School of Medicine
Wafik S El-Deiry, MD, PhD is a member of the following medical societies: American Association for Cancer Research, American Society for Clinical Investigation, and American Society of Gene Therapy
Disclosure: Nothing to disclose.

Medical Editor

Manoop S Bhutani, MD, FACG, FACP, Professor, Department of Medicine, Division of Gastroenterology, Director, Center for Endoscopic Ultrasound, Co-Director, Center for Endoscopic Research, Training and Innovation, University of Texas Medical Branch at Galveston
Manoop S Bhutani, MD, FACG, FACP is a member of the following medical societies: American Association for the Advancement of Science, American College of Gastroenterology, American College of Physicians, American Gastroenterological Association, American Institute of Ultrasound in Medicine, and American Society for Gastrointestinal Endoscopy
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

BS Anand, MD, Department of Internal Medicine, Division of Gastroenterology, Professor, Baylor University College of Medicine
BS Anand, MD is a member of the following medical societies: American Association for the Study of Liver Diseases, American College of Gastroenterology, American Gastroenterological Association, and American Society for Gastrointestinal Endoscopy
Disclosure: Nothing to disclose.

CME Editor

Alex J Mechaber, MD, FACP, 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; Consulting Staff, Department of Medicine, Section of Gastroenterology and Hepatology, Hospital of the Medical College of Pennsylvania
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 and Ethics, American Trauma Society, Association of American Medical Colleges, and Physicians for Social Responsibility
Disclosure: Nothing to disclose.

 
 
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