Official reprint from UpToDate®
www.uptodate.com ©2017 UpToDate, Inc. and/or its affiliates. All Rights Reserved.

Cap polyposis

Amy Lo, MD
Young-Mee Lee, MD
Section Editor
John R Saltzman, MD, FACP, FACG, FASGE, AGAF
Deputy Editor
Shilpa Grover, MD, MPH, AGAF


Cap polyposis is a rare condition characterized by erythematous, inflammatory colonic polyps covered by a cap of fibrinopurulent mucous. Patients usually present with mucoid diarrhea or rectal bleeding [1,2]. This topic will review the epidemiology, clinical manifestations, diagnosis, and management of cap polyposis. The approach to patient with colorectal polyps and the clinical manifestations, diagnosis, and management of other colorectal polyposis syndromes are discussed separately. (See "Clinical manifestations and diagnosis of familial adenomatous polyposis" and "Familial adenomatous polyposis: Screening and management of patients and families" and "Juvenile polyposis syndrome".)


Cap polyposis is a rare condition. The exact incidence is unknown. Cap polyposis usually occurs during the fifth decade of life; however, cases have been reported in both men and women ranging from 12 to 76 years of age [1,3,4].


The pathogenesis of cap polyposis is not well understood. Infection, mucosal ischemia, T cell-mediated inflammation, mechanical stimulation by abnormal bowel motility, and repeated trauma to the colonic mucosa caused by straining, have all been implicated in the pathogenesis.

A possible association with mucosal prolapse syndrome (MPS) has been suggested based upon similar histologic features [5-7]. It is hypothesized that in patients with cap polyposis, abnormal colonic motility may result in mucosal prolapse at redundant transverse folds, resulting in local ischemia, recurrent mucosal trauma, and the development of polyps [8]. Cap polyposis has also been described following pelvic surgery [9]. Persistent mechanical stimulation due to mucosal prolapse may lead to mucosal hyperplasia resulting in hypersecretion of serum proteins into the lumen and a protein-losing enteropathy [10].

An infectious etiology has been proposed based in part upon symptomatic and endoscopic improvement after treatment of Helicobacter pylori with antibiotics [3,9,11,12]. However, H.pylori has not been isolated within the inflammatory colonic polyps. Postulated mechanisms by which gastric H.pylori causes extra-gastric cap polyposis include molecular mimicry and the release of inflammatory mediators.

To continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information on subscription options, click below on the option that best describes you:

Subscribers log in here

Literature review current through: Oct 2017. | This topic last updated: Jun 05, 2017.
The content on the UpToDate website is not intended nor recommended as a substitute for medical advice, diagnosis, or treatment. Always seek the advice of your own physician or other qualified health care professional regarding any medical questions or conditions. The use of this website is governed by the UpToDate Terms of Use ©2017 UpToDate, Inc.
  1. Williams GT, Bussey HJ, Morson BC. Inflammatory "cap" polyps of the large intestine. Br J Surg 1985; 72:S133.
  2. Tomiyama R, Kinjo F, Kinjo N, et al. Gastrointestinal: cap polyposis. J Gastroenterol Hepatol 2003; 18:741.
  3. Akamatsu T, Nakamura N, Kawamura Y, et al. Possible relationship between Helicobacter pylori infection and cap polyposis of the colon. Helicobacter 2004; 9:651.
  4. Li JH, Leong MY, Phua KB, et al. Cap polyposis: a rare cause of rectal bleeding in children. World J Gastroenterol 2013; 19:4185.
  5. Konishi T, Watanabe T, Takei Y, et al. Confined progression of cap polyposis along the anastomotic line, implicating the role of inflammatory responses in the pathogenesis. Gastrointest Endosc 2005; 62:446.
  6. Konishi T, Watanabe T, Takei Y, et al. Cap polyposis: an inflammatory disorder or a spectrum of mucosal prolapse syndrome? Gut 2005; 54:1342.
  7. Oriuchi T, Kinouchi Y, Kimura M, et al. Successful treatment of cap polyposis by avoidance of intraluminal trauma: clues to pathogenesis. Am J Gastroenterol 2000; 95:2095.
  8. Bookman ID, Redston MS, Greenberg GR. Successful treatment of cap polyposis with infliximab. Gastroenterology 2004; 126:1868.
  9. Géhénot M, Colombel JF, Wolschies E, et al. Cap polyposis occurring in the postoperative course of pelvic surgery. Gut 1994; 35:1670.
  10. Oshitani N, Moriyama Y, Matsumoto T, et al. Protein-losing enteropathy from cap polyposis. Lancet 1995; 346:1567.
  11. Shimizu K, Koga H, Iida M, et al. Does metronidazole cure cap polyposis by its antiinflammatory actions instead of by its antibiotic action? A case study. Dig Dis Sci 2002; 47:1465.
  12. Nakagawa Y, Nagai T, Okawara H, et al. Cap polyposis (CP) which relapsed after remission by avoiding straining at defecation, and was cured by Helicobacter pylori eradication therapy. Intern Med 2009; 48:2009.
  13. Sadamoto Y, Jimi S, Harada N, et al. Asymptomatic cap polyposis from the sigmoid colon to the cecum. Gastrointest Endosc 2001; 54:654.
  14. Ng KH, Mathur P, Kumarasinghe MP, et al. Cap polyposis: further experience and review. Dis Colon Rectum 2004; 47:1208.
  15. Isomoto H, Urata M, Nakagoe T, et al. Proximal extension of cap polyposis confirmed by colonoscopy. Gastrointest Endosc 2001; 54:388.
  16. Esaki M, Matsumoto T, Kobayashi H, et al. Cap polyposis of the colon and rectum: an analysis of endoscopic findings. Endoscopy 2001; 33:262.
  17. Kajihara H, Uno Y, Ying H, et al. Features of cap polyposis by magnifying colonoscopy. Gastrointest Endosc 2000; 52:775.
  18. Isaacson P, Attwood PR. Failure to demonstrate specificity of the morphological and histochemical changes in mucosa adjacent to colonic carcinoma (transitional mucosa). J Clin Pathol 1979; 32:214.
  19. Filipe MI, Mughal S, Bussey HJ. Patterns of mucus secretion in the colonic epithelium in familial polyposis. Invest Cell Path 1980; 3:320.
  20. Filipe MI. Mucins of normal, premalignant and malignant colonic mucosa. In: Progress in cancer research and therapy, Wolman SR, Matromarino AJ (Eds), New York 1984. p.237.
  21. Habib NA, Dawson PM, Krausz T, et al. A study of histochemical changes in mucus from patients with ulcerative colitis, Crohn's disease, and diverticular disease of the colon. Dis Colon Rectum 1986; 29:15.
  22. Ehsanullah M, Filipe MI, Gazzard B. Mucin secretion in inflammatory bowel disease: correlation with disease activity and dysplasia. Gut 1982; 23:485.
  23. Buisine MP, Colombel JF, Lecomte-Houcke M, et al. Abnormal mucus in cap polyposis. Gut 1998; 42:135.
  24. Aggarwal R, Gupta P, Chopra P, Nundy S. Rectal cap polyposis masquerading as ulcerative colitis with pseudopolyposis and presenting as chronic anemia: a case study with review of literature. Saudi J Gastroenterol 2013; 19:187.
  25. Kini GP, Murray I, Champion-Young J, et al. Cap polyposis mistaken for Crohn's disease: case report and review of literature. J Crohns Colitis 2013; 7:e108.
  26. Batra S, Johal J, Lee P, Hourigan S. Cap Polyposis Masquerading as Inflammatory Bowel Disease in a Child. J Pediatr Gastroenterol Nutr 2016.
  27. Arimura Y, Isshiki H, Hirayama D, et al. Polypectomy to eradicate cap polyposis with protein-losing enteropathy. Am J Gastroenterol 2014; 109:1689.
  28. Oiya H, Okawa K, Aoki T, et al. Cap polyposis cured by Helicobacter pylori eradication therapy. J Gastroenterol 2002; 37:463.
  29. Gallegos M, Lau C, Bradly DP, et al. Cap polyposis with protein-losing enteropathy. Gastroenterol Hepatol (N Y) 2011; 7:415.
  30. Suzuki H, Sato M, Akutsu D, et al. A case of cap polyposis remission by betamethasone enema after antibiotics therapy including Helicobacter pylori eradication. J Gastrointestin Liver Dis 2014; 23:203.
  31. Chang HS, Yang SK, Kim MJ, et al. Long-term outcome of cap polyposis, with special reference to the effects of steroid therapy. Gastrointest Endosc 2012; 75:211.
  32. Kim ES, Jeen YT, Keum B, et al. Remission of cap polyposis maintained for more than three years after infliximab treatment. Gut Liver 2009; 3:325.
  33. Maunoury V, Breisse M, Desreumaux P, et al. Infliximab failure in cap polyposis. Gut 2005; 54:313.
  34. Chinen T, Misawa T, Yao T, et al. Pedunculated cap polyps preceding the development of cap polyposis: case report. Gastrointest Endosc 2005; 61:338.
  35. Ohkawara T, Kato M, Nakagawa S, et al. Spontaneous resolution of cap polyposis: case report. Gastrointest Endosc 2003; 57:599.
  36. Sasaki Y, Takeda H, Fujishima S, et al. Nine-year follow-up from onset to spontaneous complete remission of cap polyposis. Intern Med 2013; 52:351.