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Colonic Polyp

Colon Polyp

Colonic polyps arise from the mucosa of the large intestine and can be broadly categorized into neoplastic or non-neoplastic. The majority of polyps are asymptomatic, but rectorrhagia, abdominal pain or constipation may be seen. The gold standard of diagnosis and treatment is colonoscopy and polypectomy, respectively, while more extensive surgery is indicated in case of larger polyps that protrude the deeper layers of the colon.


Presentation

The vast majority of polyps do not produce any symptoms and remain undiagnosed throughout life [4]. Rectorrhagia, abdominal pain, cramping and changes in bowel habits are complaints reported in symptomatic polyps. In rare cases, large villous adenomas may cause watery diarrhea [1].

Anemia
  • The result is iron deficiency anemia, which can make you feel tired and short of breath.[mayoclinic.org]
  • Very large colon polyps and cancer can manifest with symptoms of weight loss, change in bowel habits including constipation and diarrhea , occult or even overt bleeding with anemia and abdominal pain.[mantasmd.com]
  • When signs and symptoms of colon polyps are present, they include: Rectal bleeding Anemia Diarrhea Constipation Some individuals also may experience other symptoms and signs.[emedicinehealth.com]
  • Sometimes bleeding polyps can cause fatigue and other symptoms of anemia (low levels of red blood cells). On rare occasions, a large polyp can cause diarrhea or secretion of large amounts of potassium .[drugs.com]
  • Sometimes bleeding polyps can cause fatigue and other symptoms of anemia (low levels of red blood cells). On rare occasions, a large polyp can cause diarrhea or secretion of large amounts of potassium.[drugs.com]
Axillary Mass
  • A 75-yr-old male presented with an enlarging axillary mass. Further investigation revealed an adenocarcinoma of the colon and a colonic polyp. Metastatic malignant melanoma was present within the colonic polyp and in axillary lymph nodes.[ncbi.nlm.nih.gov]
Blood in Stool
  • Colonoscopy was performed due to her complain of repeated blood in stools and subsequently the patient was misdiagnosed as a sigmoid colon polyp. Nonetheless, the "polyp" was not able to be removed endoscopically.[ncbi.nlm.nih.gov]
  • Within all the people who go to their doctor with colonic polyp, 42% report having rectal bleeding, 35% report having blood in stool, and 31% report having constipation.[symcat.com]
  • If symptoms do appear, they may include: Changes in bowel habit, including constipation or diarrhea Blood in stools (either dark, tarry stools or bright red stools) Abdominal pain If this combination of symptoms persists for more than a week, make an[coloncancer.about.com]
  • For those who do, however, symptoms may include Bleeding from the anus that may cause blood on your underwear, or on toilet paper after a bowel movement Blood in stool; black-looking, or red-streaked stool Constipation lasting more than a week Diarrhea[puristat.com]
  • stools may be an indication of rectal bleeding and should be evaluated by a doctor.[healthline.com]
Altered Bowel Function
  • Gastric anisakiasis is characterized by abdominal pain located in epigastrium, often accompanied by nausea, vomits or even altered bowel function, if it affects the duodenum.[scielo.isciii.es]
Alopecia
  • We describe a 70-year-old woman who presented with watery diarrhea and was found to have gastric and colonic polyposis, cutaneous hyperpigmentation, alopecia and onychodystrophy (Cronkhite-Canada syndrome).[ncbi.nlm.nih.gov]
Confusion
  • One was histologically confusing and raised the question of a vascular malformation. The third, seen at segmental colectomy after endosocopic biopsy of an adenoma, illustrates the gross appearances.[ncbi.nlm.nih.gov]
  • By harmonizing the thresholds for polypectomy and reporting and eliminating the polyp surveillance pathway, we could reduce confusion (both for patients and referring physicians), simplify management, and reduce costs.[doi.org]

Workup

Although some studies report that up to 20% of polyps can be missed by this procedure [10], colonoscopy is the gold standard of colonic polyp diagnosis. Firstly, a direct view into the entire colonic mucosa can be obtained and secondly, treatment can be performed during colonoscopy [11], which is why it is significantly favored over other studies such as barium enema and rectosigmoidoscopy. Colonoscopy is used to identify the number, size and location of polyps. This method also allows biopsy sampling and subsequent histopathological examination, the most important test in differentiation between polyps. In patients that have more than 20 adenomas, genetic evaluation for familial syndromes is indicated [12].

Polyps
  • In 535 patients with rectosigmoid polyps, the prevalence of proximal colonic polyps, neoplastic polyps and advanced adenomas were 33.4%, 27.3% and 2.9%, respectively.[ncbi.nlm.nih.gov]
  • Although some studies report that up to 20% of polyps can be missed by this procedure, colonoscopy is the gold standard of colonic polyp diagnosis.[symptoma.com]
  • In initial diagnosis, frequency of Adenomatous polyp, Hyperplastic polyp and Mixed polyp were 92.44% and 5.33%, and 2.22%, respectively.[ncbi.nlm.nih.gov]
  • We developed a colonic polyp detection method for CT colonographic examination that enables the detection of polyps surrounded by air and polyps surrounded by TFM without DBC.[ncbi.nlm.nih.gov]
  • The "total polyp diameter" (i.e. the sum of all polyp diameters identified during colonoscopy), which was calculated in each patient by adding the diameter of each polyp to a sum, was categorized as "small" ( or 10mm in diameter).[ncbi.nlm.nih.gov]
Liver Biopsy
  • Data were extracted from the patient charts and included demographics, anthropometric measurements, vital signs, underlying diseases, medical therapy, laboratory data, and results of the liver biopsy.[ncbi.nlm.nih.gov]
  • Data were extracted from the patient charts including demographic, anthropometric measurement, vital signs, underlying diseases, medical therapy, laboratory data, results of the liver biopsy with degree of fibrosis and necroinflammatory activity, the[ncbi.nlm.nih.gov]

Treatment

Complete removal of all potentially hazardous polyps is performed in all patients. Usually, polypectomy is performed during colonoscopy and complete excision is vital for preventing recurrence at that site [1]. Histopathological testing is important for further treatment, as colonic polyps that have protruded into deeper sections of the colon may necessitate colonic resection. Follow-up of patients with successfully removed polyps is important, as they may appear at other sites within a few years.

Prognosis

Colorectal carcinomas arise from adenomatous polyps in more than 90% of cases [3], which is why their early identification and removal is essential in preventing CRC.

A discrete malignant potential is related to hyperplastic polyps in hyperplastic polyposis syndrome.

Etiology

Colonic polyps are divided into two major categories: nonneoplastic and neoplastic. Nonneoplastic polyps include [2]:

  • Inflammatory polyps - Most commonly appear in inflammatory bowel disease (IBD), especially in ulcerative colitis.
  • Hamartomatous polyps - Juvenile polyps most commonly appear in young children, they share similar morphology with inflammatory polyps, but they may appear either as a solitary lesion or as a part of juvenile polyposis, an autosomal dominant genetic disease characterized by mutations in SMAD4 and BMPR1A [2]. Juvenile polyps are the most common subtype of hamartomatous polyps, formations that may appear in some quite rare familial syndromes such as Peutz-Jeghers syndrome, tuberous sclerosis, and Cowden's syndrome.
  • Hyperplastic polyps - Current theories state that this type of polyp stems from decreased turnover of epithelial cells, leading to accumulation of goblet cells, which is supported by the fact that it is observed primarily in elderly.

On the other hand, neoplastic polyps may be divided into tubular, tubulovillous or villous adenomas, depending on their structure. It is accepted that colonic adenomas and their progression toward carcinomas appear due to several genetic mutations, most notably in APC genes, while p53, K-ras, and DCC gene changes are other important mutations [6]. The role of dietary habits has been frequently mentioned in the pathogenesis of colorectal carcinoma but its clear association with the formation of colonic polyps remain to be solidified.

Epidemiology

Studies have estimated various prevalence rates of colonic polyps. Postmortem examinations show a prevalence rate of 40-60% after 60 years [4] while screening colonoscopy revealed an estimated overall prevalence rate of 27% [7]. In addition to advanced age, several risk factors for malignant transformation such as tobacco smoking, alcohol consumption and family history of adenomatous polyps are established [8].

Sex distribution
Age distribution

Pathophysiology

The pathogenesis of adenomatous colonic polyps remains incompletely understood, but genetic factors seem to play the biggest role, especially in familial forms. Mutations in the APC gene is thought to be the single most important step in the pathogenesis of these lesions, followed by p53, K-ras and DCC, but the complete model remains to be elucidated [2]. BRAF mutations have been observed in certain adenoma subtypes as well [9]. The propensity of adenomatous polyps to advance toward malignant lesions is the base of their extraordinary clinical significance. This behavior is particularly related to large, sessile adenomas with a significant amount of villous component.

In hyperplastic polyps, alterations in normal cell shedding lead to accumulation of goblet cells. In familial adenomatous polyposis, the key genetic event is the mutation in the adenomatous polyposis coli gene . In Peutz-Jeghers syndrome, mutations in LKB1/STK11 genes occur, while Juvenile polyposis is characterized by SMAD4 and BMPR1A gene alterations [2].

Prevention

Since the mechanism of polyp formation remains unclear, little can be done to prevent their occurrence. However, wide-scale screening of patients has shown remarkable results in detecting polyps in their early stages. In fact, approximately 20-30% of adenomas are detected by screening [11], and marked reductions in cost as well as treatment difficulties by screening methods have been observed [13]. For these reasons, certain guidelines suggest performing a colonoscopy every 1-3 years, depending on the presence of risk factors and previous colonoscopy findings [4], so that the diagnosis of colonic polyps is made early on.

Summary

Colonic polyps are an important clinical entity as some forms lead to colorectal cancer (CRC), one of the most common and most lethal malignancies worldwide. In terms of appearance, polyps may be described as sessile or pedunculated, while further classification based on morphology and histological appearance divides colonic polyps into neoplastic and nonneoplastic [1]. Hyperplastic, inflammatory and hamartomatous polyps comprise the nonneoplastic group, which can appear either as solitary lesions or as a part of some familial syndromes, such as Peutz-Jeghers syndrome, Cowden's syndrome and tuberous sclerosis [2]. Various forms of adenomatous polyps, on the other hand, are premalignant lesions that lead to CRC in up to 90% of cases, according to some studies [3]. Prevalence of adenomatous polyps at 60 years of age ranges between 30-40%, but significant variations in these rates exist [4]. Larger polyp diameter (> 10 mm) is shown to be one of the most important risk factors for its progression into malignancy [4]. In addition to the lesion size, its appearance within familial syndromes such as hereditary nonpolyposis colorectal cancer and familial adenomatous polyposis is also considered to be a risk factor. Several mutations have been identified in adenomatous polyps and their progression toward malignant change, including involvement of APC, p53, K-ras and DCC genes. Mutations of the adenomatous polyposis coli (APC) gene are the key event in familial adenomatous polyposis (FAP). Patients are usually asymptomatic, especially in the presence of polyps that are smaller in diameter (<10mm). The most frequent symptoms involve rectorrhagia, abdominal pain, and alterations in normal bowel functioning [5]. Colonoscopy is the main diagnostic procedure in the case of colonic polyps, which are easily detected by this method. A full inspection of the colon is necessary to assess the number of polyps, as well as their size, in order to proceed with treatment. In addition to its superiority to barium enema and rectosigmoidoscopy, treatment can be performed during colonoscopy, which primarily includes polypectomy. In the setting of deeper involvement, colon resection can be indicated [1]. Because of the fact that adenomatous polyps often lead to CRC, screening and removal of polyps in early stages are one of the most important strategies in preventing cancer of the colon.

Patient Information

Colonic polyps are pathological formations that arise from the colonic mucosa and are generally classified into those that may progress to colorectal cancer and those that may not. Adenomatous polyps are considered as prerequisite lesions to colon cancer, as some studies have determined that up to 90% of colorectal cancer arise from these polyps. Other colonic polyps, such as inflammatory, hyperplastic and hamartomatous polyps are either isolated findings or they may be a part of certain genetic syndromes. Adenomatous polyps can also appear in familial syndromes. Familial adenomatous polyposis, Peutz-Jeghers syndrome, Cowden's syndrome and tuberous sclerosis are diseases in which large numbers of polyps appear. The exact reason why these polyps develop remains unclear, but mutations of numerous genes have been identified, leading to the fact that genetic processes are the most likely cause. Smoking, alcohol consumption, increased polyp size (> 10 mm) and number are proposed as risk factors for progression to colorectal cancer. Colonic polyps are a somewhat common finding in elderly patients, as prevalence rates are estimated to range from 40-60%, but they may often go undetected, as they rarely cause any symptoms. Large polyps could, however, cause rectal bleeding, abdominal pain and bloating. To make the diagnosis of colonic polyps, colonoscopy is the single most important procedure, which comprises insertion of an endoscope into the rectum and subsequent visualization of the entire large intestine. This procedure is favored over barium enema and rectosigmoidoscopy (a procedure that evaluates only the last third of the colon) due to its ability to identify polyps with precision, but more importantly because treatment can be carried out during this procedure. The overall goal of treatment is to maximally reduce the chance of colon cancer development. All polyps should be removed and microscopically examined to determine the exact type, in order to plan further treatment and follow-up strategies. In the case of large polyps that protrude in deeper layers of the colon wall, resection of the colon may be indicated. Since the introduction of colonoscopy in regular practice, prevention by means of massive screening for colonic polyps has shown to be quite effective, as 20-30% of polyps are shown to be identified during screening. Depending on previous colonoscopic findings, guidelines for prevention suggest regular follow-ups at every 1-3 years, so that effective reduction in the burden of colorectal cancer can be achieved.

References

Article

  1. Porter RS, Kaplan JL. Merck Manual of Diagnosis and Therapy. 19th Edition. Merck Sharp & Dohme Corp. Whitehouse Station, N.J; 2011.
  2. Aster, JC, Abbas, AK, Robbins, SL1, Kumar, V. Robbins basic pathology. Ninth edition. Philadelphia, PA: Elsevier Saunders; 2013.
  3. Neri E, Faggioni L, Cini L, Bartolozzi C. Colonic polyps: inheritance, susceptibility, risk evaluation, and diagnostic management. Cancer Management and Research. 2011;3:17-24.
  4. Atkin WS, Saunders BP. Surveillance guidelines after removal of colorectal adenomatous polyps. Gut. 2002;51;v6-v9.
  5. Adelstein BA, Macaskill P, Chan SF, et al. Most bowel cancer symptoms do not indicate colorectal cancer and polyps: a systematic review. BMC Gastroenterol. 2011;11:65.
  6. Cappell MS. From colonic polyps to colon cancer: pathophysiology, clinical presentation, screening and colonoscopic therapy. Minerva Gastroenterol Dietol. 2007;53(4):351-373.
  7. Rex DK, Lehman GA, Ulbright TM, et al. Colonic neoplasia in asymptomatic persons with negative fecal occult blood tests: influence of age, gender, and family history. Am J Gastroenterol. 1993;88:825-831.
  8. Giacosa A1, Frascio F, Munizzi F. Epidemiology of colorectal polyps. Tech Coloproctol. 2004;8(2):243-247.
  9. Spring KJ, Zhao ZZ, Karamatic R, et al. High prevalence of sessile serrated adenomas with BRAF mutations: a prospective study of patients undergoing colonoscopy. Gastroenterology. 2006;131(5):1400-1407.
  10. Yeung TM, Mortensen NJ. Advances in endoscopic visualization of colorectal polyps. Colorectal Dis. 2011;13:352-329.
  11. Bond JH. Colon polyps and cancer. Endoscopy. 2005;37(3):208-212.
  12. Perencevich M, Stoffel EM. A Multidisciplinary Approach to the Diagnosis and Management of Multiple Colorectal Polyps. Gastroenterology & Hepatology. 2011;7(6):420-423.
  13. Heresbach D, Chauvin P, Hess-Migliorretti A, Riou F, Grolier J, Josselin JM. Cost-effectiveness of colorectal cancer screening with computed tomography colonography according to a polyp size threshold for polypectomy. Eur J Gastroenterol Hepatol. 2010;22(6):716-723.

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Last updated: 2019-07-11 22:11