Pseudopolyps

Pseudopolyps also called inflammatory polyps, post-inflammatory polyps or inflammatory pseudopolyps, formed as a consequence of alternating cycles of inflammation and regeneration of the ulcerated epithelium ¹. Pseudopolyps form as islands of regenerating mucosa and granulation tissue surrounded by sections of ulceration bulge into the intestinal lumen ². Inflammatory pseudopolyps also contain a submucosal core as the tissue heals. The term pseudopolyps, however, has been applied to the characterization of surviving islets of mucosa between ulcers during a severe attack, which create the impression of a polyp ³ and of loose mucosal tags, which are formed because of severe ulceration undermining the integrity of the muscularis mucosa. In conjunction with the inflammation process and cellular infiltration of the submucosa, granulation tissue is formed, which is more intense in some focal areas, thereby producing inflammatory pseudopolyps ⁴. During the healing process, which features re-epithelization and excessive regeneration, post-inflammatory pseudopolyps are formed ⁵, taking their shape from the elongation of mucosal tags related to the bowel’s peristaltic contractions and the stream of feces ⁶. From this perspective, the post-inflammatory polyps can be separated into the following categories: (1) pseudopolyps; (2) inflammatory polyps; and (3) post-inflammatory polyps ⁷.

Pseudopolyps are thought to develop as a result of repeated alternating cycles of inflammation and healing of the intestinal mucosa in patients with chronic inflammatory conditions ⁸. Pseudopolyps are usually confined to the colon. Inflammatory pseudopolyps are encountered in 20%–45% of patients with inflammatory bowel disease (IBD) and colonic involvement ⁹. There is a subgroup of patients with ulcerative colitis (10-20%) who present on endoscopy with pseudopolyps, typically formed at the bowel wall during repetitive inflammation attacks ¹⁰. Pseudopolyps have been associated with an increased burden of disease in the context of intermediate risk of colorectal cancer and the need for increased surveillance ¹¹. However, another study showed there is no convincing evidence that inflammatory pseudopolyps undergo dysplastic or neoplastic changes ¹². And according to new findings ¹³, pseudopolyp were shown to not be associated with colorectal neoplasia in patients with inflammatory bowel disease (IBD). Furthermore, patients with inflammatory pseudopolyps had more severe histologic inflammation, more often had extensive colitis, and were significantly more likely to undergo colectomy ¹³. The new findings suggest that inflammatory pseudopolyps are related to the inflammatory burden, but are not themselves a dominant risk factor for colorectal neoplasia ¹³.

Pseudopolyps generally are seen in patients with more severe and widely distributed inflammation ¹⁴. Inflammatory polyposis can develop in patients within a short period of time after the onset of clinically recognized inflammation, and pseudopolyps may be seen during the first acute attack of inflammatory bowel disease ¹⁴. Pseudopolyps are seen in patients with active or quiescent inflammatory bowel disease ¹⁵. Patients with inflammatory bowel disease complicated by dilation and megacolon are also more likely to have inflammatory polyposis ¹⁴. Besides the well‐recognized symptoms and complications that are usually associated with inflammatory bowel disease, the presence of inflammatory polyposis may be associated with unique complications. Colonic obstruction has been caused by inflammatory polyposis in patients with ulcerative colitis, even in the absence of acute inflammation ¹⁶. Protein‐losing enteropathy has also occurred in this setting ¹⁷. Filiform polyposis is the term used to describe the presence of slender, finger‐like projections protruding into the lumen of the colon from the mucosal surface, most often in patients with inflammatory bowel disease ¹⁸. The projections are composed of cores of normal submucosa surrounded by minimally inflamed mucosa. Such lesions were first described in middle‐aged patients years after an episode of acute colitis ¹⁹. Filiform polyposis has been described in patients with both forms of idiopathic inflammatory bowel disease ¹⁸. These lesions may cause obstruction, hemorrhage or may be asymptomatic in patients with otherwise quiescent inflammatory bowel disease ¹⁸. In addition to being found in the colon, filiform polyposis has also been seen in the stomach in a patient with Crohn’s disease involving the small bowel ²⁰.

Inflammatory polyposis has also been reported in association with other conditions besides inflammatory bowel disease, including ischemic colitis ²¹. Infectious colitis may sometimes result in inflammatory polyposis. Twelve of 25 patients with tuberculous colitis were shown to have inflammatory polyposis in one series ²². A Caucasian man developed amoebic colitis associated with extensive pseudopolyps after traveling to India ²³. Polyposis has also been reported in Egyptian patients with schistosomal disease of the colon ²⁴ and in one man from the Aegean island of Mytilinae who had colitis due to infestation with Balantidium coli, a parasite that commonly infects pigs ²⁵. Another interesting case report describes inflammatory polyposis in a Korean patient diagnosed with Behçet’s disease ²⁶. Finally, multiple pseudopolyps were seen in an ileal blind loop in a patient who had undergone partial gastrectomy and Billroth II gastrojejunostomy for peptic ulcer disease 11 years before presenting with symptoms of chronic diarrhea. This patient had no history of other findings consistent with inflammatory bowel disease ²⁷.

A condition known as cap polyposis may be a variant of inflammatory polyposis. First described in 1985, this condition is not associated with inflammatory bowel disease but rather tends to occur in patients with mucosal prolapse ²⁸. The lesions consist of elongated, tortuous and occasionally distended crypts covered with a `cap’ of inflammatory granulation tissue. They are usually distributed from the rectum to the distal descending colon ²⁸. Patients typically present with diarrhea, tenesmus, hematochezia ²⁹ and protein‐losing enteropathy ²⁸. In at least one patient, avoidance of straining during defecation resulted in symptomatic and endoscopic improvement, but in some patients surgery has been required ²⁸.

Figure 1. Pseudopolyps

Footnote: Examples of various types of pseudopolyps in different patients with inflammatory bowel disease. (A) Endoscopic picture of deep ulcers and residual islets of surviving mucosa, the “true” pseudopolyps; (B) Localized pseudopolyps of varying size up to 1.6 cm with discrete borders, pale surface, exudates on surface and varying forms. Biopsy of the polyps revealed inflammatory infiltration of lymphocytes, distortion and branching of the crypts compatible with post inflammatory pseudopolyps; (C) Long filiform pseudopolyp located in the transverse colon captured with biopsy forceps; (D) Localized filiform pseudopolyposis located in sigmoid colon; (E) Post-inflammatory generalized pseudopolyposis; (F) Cluster of pseudopolyps in sigmoid colon with 2.5 cm size, creating a giant localized pseudopolyp. Multiple biopsies of the polyp showed lined epithelium with a core of connective tissue and vessels with inflammatory infiltration which confirmed the diagnosis of pseudopolyp; (G) Multiple pseudopolyps stubble the sigmoid colon. In this case, surveillance for dysplasia-associated lesion or mass can be challenging because of the intense inflammation and the multiple pseudopolyps; (H) Pseudopolyp or adenoma-like mass? Solitary polyp with 1.5 cm size and broad-based with discrete borders but without exudates, amenable to endoscopic removal and having a pale surface. Histology after removal of the polyp with electrocautery showed villous adenoma with mild dysplasia, and without dysplasia in the surrounding mucosa or elsewhere in the colon, compatible with adenoma-like mass; (I) Localized post-inflammatory pseudopolyps; (J) Localized pseudopolyps of 0.3 cm maximum size, located in sigmoid colon with discrete borders and pale, glistering surface. Endoscopic characteristics were adequate for recognition of pseudopolyps without the need for biopsies or further intervention.

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Pseudopolyps key facts

• Pseudopolyps are markers of episodes of severe inflammation, encountered in endoscopy in a subgroup of patients with ulcerative colitis.
• Their clinical significance is uncertain, except for their link with an intermediate risk for colorectal cancer
• Pseudopolyps are not included in endoscopic scores for monitoring the activity of ulcerative colitis
• The presence of pseudopolyps in patients with ulcerative colitis was associated with rapid escalation of treatment, escalation to biological agents or surgery, and possibly with bowel stenosis
• The presence of pseudopolyps in ulcerative colitis patients was not associated with a greater need for hospitalization
• Patients with ulcerative colitis and pseudopolyps may represent a subgroup with a greater burden of disease in terms of increased immunosuppressive treatment.

The presence of inflammatory pseudopolyps in a patient with inflammatory bowel disease can be an indirect marker of previous episodes of severe inflammation, and their incidence rises with more extensive colitis. Although there are not any clear prognostic criteria predicting their formation, it is a common belief that intense flares and hyperplastic healing predispose to inflammatory pseudopolyp formation. A cornerstone study by De Dombal et al ³⁰, involving 465 patients with ulcerative colitis, has shown that 19.5% of patients with total colitis had inflammatory pseudopolyps and 38% of the patients with inflammatory pseudopolyps had suffered at least one episode of severe flare; in addition, 57.1% of the patients who underwent colectomy to address fulminant ulcerative colitis in 1956 had inflammatory pseudopolyp. This high prevalence can be attributable to severe active disease ³¹. Teague et al ³² expressed a similar opinion, citing a inflammatory pseudopolyp prevalence of 41% in 48 patients with total colitis, and Jalan et al ⁴ reported that 31% of patients with severe ulcerative colitis had inflammatory pseudopolyp.

In regards to predicting inflammatory pseudopolyp formation, Babic et al ³³ proposed that elevation in two of the three following parameters-C-reactive protein, C4 and procollagen III peptide-accompany formation of inflammatory pseudopolyp in ulcerative colitis, calculating the positive predictive value and accuracy to be as high as 90% and 93%, respectively. The existence of inflammatory pseudopolyp has also been linked with the occurrence of extra-intestinal symptoms, specifically arthropathy ⁴. Their presence in general, however, does not characterize any specific phase of inflammatory bowel disease, as they can be found in both active and quiescent disease states, with the exception of the first form (i.e., the mucosal remnants) which are only found in active inflammatory bowel disease ³⁴.

Pseudopolyps and cancer

Patients with inflammatory pseudopolyp are considered to be at intermediate risk for colorectal cancer. United Kingdom guidelines suggest surveillance colonoscopy be performed at a 3-year interval ³⁵, European Crohn’s and Colitis Organization guidelines suggest colonoscopy at 2- or 3-year intervals ³⁶ and the American Society for Gastrointestinal Endoscopy suggests between 1- and 3-year intervals ³⁷. Three studies, performed by Rutter et al ³⁸, Velayos et al ³⁹ and Baars et al ⁴⁰, have shown a near 2-fold increased risk of colorectal cancer in patients with previous or present inflammatory pseudopolyp in endoscopy. In much older reports, there was a debate about the possibility of inflammatory pseudopolyp malignant transformation, with advocates representing both sides. Among these, Goldgraber et al ³ reported a case series of several forms of inflammatory pseudopolyp with some showing premalignant changes, but later analysis proved these were benign lesions, regardless of size ⁴.

Nowadays, malignant transformation of inflammatory pseudopolyp is considered an extremely rare event, with only two reports of giant inflammatory pseudopolyp harboring carcinoma or dysplasia features ⁵, ⁴¹. Another case report from Klarskov et al ⁴² presented a carcinoma in rectum stump that had arose from serrated adenoma with a filiform form. The authors speculated that the serrated adenoma had derived from transformation of preexisting inflammatory pseudopolyp. A possible mechanism has been implicated by Jawad et al ⁴³, who reported that inflammatory pseudopolyp can be the source of premalignant mutations, following their analysis of DNA taken from 30 inflammatory pseudopolyp samples and which showed four identifiable mutations. However, more studies are needed to confirm the doubt in their benign nature.

A possible explanation about the relationship between inflammatory pseudopolyp and increased risk of colorectal cancer lies in the facts that they are considered markers of episodes of previous severe inflammation and that their incidence of appearance rises with the increased extent of colitis ³⁰, which is in turn linked to colorectal cancer. Another possible explanation is that their presence, especially if they are numerous, can obscure the capability of finding dysplastic lesions in endoscopic surveillance ³⁹.

Pseudopolyps distinct forms

Inflammatory pseudopolyps exist in a variety of forms, including sessile, frond-like and pedunculated, and they can occur as solitary or multiple, or as diffuse or localized in distribution ³. They also vary in size, but are usually short. When a inflammatory pseudopolyp exceeds 1.5 cm in size (Figure 1B), the term giant pseudopolyp has prevailed for their characterization ⁴⁴, with this description first appearing in the literature in 1965 ³.

A distinct form of the post-inflammatory polyps is the filiform polyps. These appear as slender, finger-like or worm-like projections of the mucosa and sub-mucosa, and look like a polyp stalk without a head and often with branching (Figure 1C and 1D) ⁴⁵. They often create a cluster, and as such are termed as localized giant pseudopolyposis (Figure 1E and 1F) ⁴⁶. In the literature, the term filiform polyposis often accounts for giant inflammatory pseudopolyps ⁴⁷. Another distinct form of the post-inflammatory polyps is the bridged inflammatory pseudopolyp, representing a mucosal bridge that formed from a long filiform polyp connecting to the opposite end of the lumen ⁴⁸.

Inflammatory pseudopolyp location and distribution

inflammatory pseudopolyps are more commonly encountered in large intestine, likely due to this tissue being affected in both ulcerative colitis and Crohn’s disease. The most common site is transverse colon and, thereafter, descending and sigmoid colon, with rectum being the least common site; moreover, inflammatory pseudopolyp in the rectum are usually found at the upper third region ³⁰. The giant inflammatory pseudopolyps show similar topographic occurrence ⁴⁷. However, as Crohn’s disease can involve the entire gastrointestinal tract, the inflammatory pseudopolyps can be present throughout but have been detected less often in extra-colonic regions. There is an exception to this distribution pattern for ulcerative colitis patients with backwash ileitis, wherein inflammatory pseudopolyps have also been found at the terminal ileum ⁴⁹. There are also reports of inflammatory pseudopolyps located at the esophagus ⁵⁰, stomach ⁵¹, and different parts of the small bowel ⁵², with ileum presentation predominating in the latter ⁵³. There is one case report of a Crohn disease patient with pansinusitis location of inflammatory pseudopolyp, which regressed with medical therapy ⁵⁴, and another case report of a patient with refractory pouchitis who presented with a large inflammatory pseudopolyp located in an affected pouch ⁵⁵.

Pseudopolyps treatment

Questions remain about the optimal management or follow-up strategies for inflammatory pseudopolyp, especially for cases with multiple inflammatory pseudopolyp, because no large trials have been published regarding these issues.

A great matter of concern involves distinguishing them from adenoma-like dysplasia-associated lesion or mass (DALM) and non-adenoma-like DALM (Figure 1H). Even though some diagnostic endoscopic criteria may be used for recognizing inflammatory pseudopolyp, they are not completely reliable ⁵⁶. There can be good inter-observer agreement for identifying inflammatory pseudopolyp during endoscopy in general ⁵⁷, but when it comes to distinguishing inflammatory pseudopolyp from other dysplastic lesions, the efficiency falls. Farraye et al ⁵⁸ performed an internet-based study and found that gastroenterologists with non-inflammatory bowel disease-specialized expertise had lower capability of distinguishing different forms of lesions in inflammatory bowel disease patients.

Chromo-endoscopy might aid in differential diagnosis, since inflammatory pseudopolyps (as non-neoplastic polyps) show Kudo’s pattern classification of type II ⁵⁹. In another study by Koinuma et al ⁶⁰, magnifying endoscopy was demonstrated as a useful tool for distinguishing neoplastic from non-neoplastic lesions, reducing the amount of biopsies needed; however, the efficacy of this technique for studying the underlying inflammatory process was shown to be limited by the presence of multiple inflammatory pseudopolyps ⁵⁶. In another study, 165 patients with long-standing ulcerative colitis were divided and randomized for endoscopic surveillance by means of either conventional endoscopy (with biopsies every 10 cm) or chromo-endoscopy (with 0.1% methylene blue); there were two false-negative results that were not identified by the chromo-endoscopy procedure, for which non-targeted biopsies from colons with multiple inflammatory pseudopolyp proved to contain dysplasia ⁶¹.

Nevertheless, in cases where there is either doubt about the diagnosis of inflammatory pseudopolyp, suspicion of DALM or large-size inflammatory pseudopolyp, or presence of multiple inflammatory pseudopolyp wherein endoscopic surveillance is compromised, multiple biopsies should be obtained in repeated examinations ⁶² or proceeding the endoscopic or surgical removal, with surrounding tissue examination by biopsy as well ⁶³.

There is a general acceptance that if inflammatory pseudopolyp are adequately recognized using endoscopic criteria and do not provoke any complications, no removal is considered obligatory ⁵⁸. However, it is considered mandatory that the surface of any inflammatory pseudopolyp be surveyed adequately during endoscopy. In older reports, especially of cases with large inflammatory pseudopolyp, surgical intervention was frequently performed for the removal, due to confusion with colorectal cancer or villous adenoma and related to the more common use of radiological approaches, such as barium enema, for diagnosis and monitoring ⁶⁴. Nowadays, however, endoscopic surveillance is more effective than surgical intervention ⁶⁵.

In the same context, the discovery of inflammatory pseudopolyp in a patient with inflammatory bowel disease, without evidence of suspicious lesions in endoscopy and in which the presence of inflammatory pseudopolyp does not obstruct adequate endoscopic surveillance of the mucosa, should not urge gastroenterologists towards more intense endoscopic follow-up. Neither should it discourage them from the use of chromo-endoscopy for surveillance in any manner other than those proposed in the various guidelines (with an approximate 3-year interval), and certainly not in a different way than would be performed in patients without inflammatory pseudopolyps ³⁷. As mentioned before, colorectal cancer derived from inflammatory pseudopolyp is a rare event and occurrence of inflammatory pseudopolyp has not been linked with early colorectal cancer ⁶⁶. Therefore, screening for colorectal cancer in all patients with inflammatory pseudopolyp is not recommended before 8-10 years after onset of symptoms ³⁷.

Medical treatment has been used for inflammatory pseudopolyp and shown to induce regression. Choi et al ⁶² reported regression of giant inflammatory pseudopolyp in patients with inflammatory bowel disease upon administration of mesalazine and azathioprine. Infliximab has also been shown to induce regression of inflammatory pseudopolyp in Crohn’s disease ⁶⁷. Topical enema with budenoside use was also reported to induce remission and control of minor bleeding of inflammatory pseudopolyp in sigmoid colon ⁶⁸.

Endoscopic procedures such as argon plasma coagulation ⁶⁹, endoscopic loop polypectomy ⁷⁰, and ablation with yttrium aluminium garnet (commonly referred to as YAG) laser have been reported for control of bleeding provoked by ulcerated inflammatory pseudopolyp ⁷¹. Endoscopic resection with electrocautery is another effective means reported for removing either symptomatic inflammatory pseudopolyps or inflammatory pseudopolyps of which their benign nature was not able to be established only with endoscopic criteria and which need further histological evaluation ⁷².

Surgical methods are used when endoscopic therapy fails to manage complicated inflammatory pseudopolyp, for example in lower gastrointestinal bleeding or when obstructing phenomena, such as luminal obliteration or intussusception, occur ⁶⁴. The various surgical procedures range from segmental dissection to hemicolectomy ⁷³, depending on the cause. However, with the recent advances in endoscopic treatment, the need for a surgical approach has lessened over time.

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