Sessile serrated adenoma/polyps: Where are we at in 2016?

It is currently known that colorectal cancers(CRC) arise from 3 different pathways: the adenoma to carcinoma chromosomal instability pathway(50%-70%); the mutator "Lynch syndrome" route(3%-5%); and the serrated pathway(30%-35%). The World Health Organization has classified serrated polyps into three types of lesions: hyperplastic polyps(HP),sessile serrated adenomas/polyps(SSA/P) and traditional serrated adenomas(TSA),the latter two strongly associated with development of CRCs. HPs do not cause cancer and TSAs are rare. SSA/P appear to be the responsible precursor lesion for the development of cancers through the serrated pathway. Both HPs and SSA/Ps appear morphologically similar. SSA/P are difficult to detect. The margins are normally inconspicuous. En bloc resection of these polyps can hence be troublesome. A careful examination of borders,submucosal injection of a dye solution(for larger lesions) and resection of a rim of normal tissue around the lesion may ensure total eradication of these lesions.

Solitary rectal ulcer syndrome complicating sessile serrated adenoma/polyps: A case report and review of literature

Solitary rectal ulcer syndrome(SRUS) is a rare benign condition, which can mimic many other diseases because of their similarities in clinical, endoscopic and histological features. Sessile serrated adenoma/polyp(SSA/p) is a premalignant lesion in the colon and rectum. The misdiagnosis of SSA/p in SRUS patients has been noted, but the case of SRUS arising secondarily to SSA/p has been rarely reported. We herein report the case of a 59-year-old man who presented with an ulcerative nodular lesion in the rectum, accompanied by the symptoms of blood and mucus in the feces, diarrhea and constipation. Magnetic resonance imagining revealed thickening of the rectal mucosa-submucosa. Histologically, the lesion was characterized by the hyperplastic lamina propria and diffusely serrated crypts. Further immunohistochemical staining showed the loss of HES1 and MLH1 expression in the epithelial cells in the serrated area. The patient with SRUS had histological changes of SSA/p, suggesting a potential of tumor transformation in certain cases. SRUS uncommonly accompanied by serrated lesions should at least be considered by pathologists and clinicians.

Clinicopathological features and expression of regulatory mechanism of the Wnt signaling pathway in colorectal sessile serrated adenomas/polyps with different syndrome types

BACKGROUND Colorectal cancer(CRC)is the third most common cancer worldwide,with the fourth highest mortality among all cancers.Reportedly,in addition to adenomas,serrated polyps,which account for 15%-30%of CRCs,can also develop into CRCs through the serrated pathway.Sessile serrated adenomas/polyps(SSAs/Ps),a type of serrated polyps,are easily misdiagnosed during endoscopy.AIM To observe the difference in the Wnt signaling pathway expression in SSAs/Ps patients with different syndrome types.METHODS From January 2021 to December 2021,patients with SSAs/Ps were recruited from the Endoscopy Room of Shanghai Traditional Chinese Medicine-Integrated Hospital,affiliated with Shanghai University of Traditional Chinese Medicine.Thirty cases each of large intestine damp-heat(Da-Chang-Shi-Re,DCSR)syndrome and spleen-stomach weakness(Pi-Wei-Xu-Ruo)syndrome were reported.Baseline comparison of the general data,typical tongue coating,colonoscopy findings,and hematoxylin and eosin findings was performed in each group.The expression of the Wnt pathway-related proteins,namelyβ-catenin,adenomatous polyposis coli,and mutated in colorectal cancer,were analyzed using immunohistochemistry.RESULTS Significant differences were observed with respect to the SSAs/Ps size between the two groups of patients with different syndrome types(P=0.001).The other aspects did not differ between the two groups.The Wnt signaling pathway was activated in patients with SSAs/Ps belonging to both groups,which was manifested asβ-catenin protein translocation into the nucleus.However,SSAs/Ps patients with DCSR syndrome had more nucleation,higherβ-catenin expression,and negative regulatory factor(adenomatous polyposis coli and mutated in colorectal cancer)expression(P<0.0001)than SSA/P patients with Pi-Wei-Xu-Ruo syndrome.In addition,the SSA/P size was linearly correlated with the related protein expression.CONCLUSION Patients with DCSR syndrome had a more obvious Wnt signaling pathway activation and a higher risk of carcinogenesis.A high-quality colonoscopic diagnosis was essential.The thorough assessment of clinical diseases can be improved by combining the diseases of Western medicine with the syndromes of traditional Chinese medicine.

Endoscopic diagnosis of sessile serrated adenoma/polyp with and without dysplasia/carcinoma

Sessile serrated adenoma/polyps(SSA/Ps) are early precursor lesions in the serrated neoplasia pathway, which results in colorectal carcinomas with BRAF mutations, methylation for DNA repair genes, a Cp G island methylator phenotype, and high levels of microsatellite instability. Some of these lesions can rapidly become dysplastic or invasive carcinomas that exhibit high lymphatic invasion and lymph node metastasis potentials. Detecting serrated lesions, including SSA/Ps with and without dysplasia/carcinoma, is critical, but SSA/Ps can be difficult to detect, are inconsistently identified by endoscopists and pathologists, and are often incompletely resected. Therefore, SSA/Ps are considered to be major contributors to "interval cancers". If colonoscopists can identify the specific endoscopic characteristics of SSA/Ps, their detection and the effectiveness of colonoscopy may improve. Here, the endoscopic features of SSA/Ps with and without dysplasia/carcinoma, including the characteristics determined using magnifying endoscopy, are reviewed in the context of previous reports. Endoscopically, these subtle polyps are like hyperplastic polyps, because they are slightly elevated and pale. Unlike hyperplastic polyps, SSA/Ps are usually larger than 5 mm, frequently covered by a thin layer called the ‘‘mucus cap'', and are more commonly located in the proximal colon. Magnifying narrow-band imaging findings, which include dark spots inside the crypts and varicose microvascular vessels, in addition to the type II-open pit patterns detected using magnifying chromoendoscopy, effectively differentiate SSA/Ps from hyperplastic polyps. The lesions' endoscopic characteristics, which include their(semi)pedunculated morphologies, double elevations, central depressions, and reddishness, and the use of magnifying endoscopy, might help to detect dysplasia/carcinoma within SSA/Ps. Greater awareness may promote further research into improving the detection, identification, and complete resection rates of SSA/Ps with and without dysplasia/carcinoma and reduce the interval cancer rates.

How to"pick up"colorectal serrated lesions and polyps in daily histopathology practice:From terminologies to diagnostic pitfalls

Over the last decade,our knowledge of colorectal serrated polyps and lesions has significantly improved due to numerous studies on this group of precursor lesions.Serrated lesions were misleading as benign before 2010,but they are currently reclassified as precancerous lesions that contribute to 30%of colorectal cancer through the serrated neoplasia pathway.The World Health Organization updated the classification for serrated lesions and polyps of the colon and rectum in 2019,which is more concise and applicable in daily practice.The responsible authors prescribe that“colorectal serrated lesions and polyps are characterized by a serrated(sawtooth or stellate)architecture of the epithelium.”From a clinical standpoint,sessile serrated lesion(SSL)and SSL with dysplasia(SSLD)are the two most significant entities.Despite these advancements,the precise diagnosis of SSL and SSLD based mainly on histopathology remains challenging due to various difficulties.This review describes the nomenclature and the terminology of colorectal serrated polyps and lesions and highlights the diagnostic criteria and obstacles encountered in the histopathological diagnosis of SSL and SSLD.

Sessile serrated adenomas:Demographic,endoscopic and pathological characteristics

AIM:To study the demographic and endoscopic characteristics of patients with sessile serrated adenoma(SSA) in a single center.METHODS:Patients with SSA were identified by review of the pathology database of Mayo Clinic Arizona from 2005 to 2007.A retrospective chart review was performed to extract data on demographics,polyp characteristics,presence of synchronous adenomatous polyps or cancer,polypectomy methods,and related complications.RESULTS:One hundred and seventy-one(2.9%) of all patients undergoing colonoscopy had a total of 226 SSAs.The mean(SE) size of the SSAs was 8.1(0.4) mm;42% of SSAs were ≤ 5 mm,and 69% were ≤ 9 mm.Fifty-one per cent of SSAs were located in the cecum or ascending colon.Approximately half of the patients had synchronous polyps of other histological types,including hyperplastic and adenomatous polyps.Synchronous adenocarcinoma was present in seven(4%) cases.Ninety-seven percent of polyps were removed by colonoscopy.CONCLUSION:Among patients with colon polyps,2.9% were found to have SSAs.Most of the SSAs were located in the right side and were safely managed by colonoscopy.

Interendoscopist variability in proximal colon polyp detection is twice higher for serrated polyps than adenomas

AIM To assess the interendoscopist variability in the detection of colorectal polyps according to their location and histological type.METHODS This study was a retrospective analysis of prospectively collected data from a regional colorectal cancer(CRC) screening program; 2979 complete colonoscopies from 18 endoscopists were included. Variability in performance between endoscopists for detection of at least one adenoma(A), one proximal adenoma(PA), one distal adenoma(DA), and one proximal serrated polyp(PSP) was assessed by using multilevel logistic regression models.RESULTS The observed detection rates among the 18 endoscopists ranged from 24.6% to 47.6%(mean = 35.7%) for A, from 19.1% to 39.0%(mean = 29.4%) for DA, from 6.0% to 22.9%(mean = 12.4%) for PA, and from 1.3% to 19.3%(mean = 6.9%) for PSP.After adjusting for patient-level variables(sex, age), the interendoscopist detection rates variability achieved a significant level for A, PA, and PSP but not for DA(P = 0.03, P = 0.02, P = 0.02 and P = 0.08, respectively). This heterogeneity, as measured by the variance partition coefficient, was approximately threefold higher for PA(6.6%) compared with A(2.1%), and twofold higher for PSP(12.3%) compared with PA.CONCLUSION These results demonstrate significant interendoscopist variability for proximal polyp particularly for serrated p o l y p s, b u t n o t f o r d i s t a l a d e n o m a d e t e c t i o n. These findings contribute to explain the decreased effectiveness of complete colonoscopies at preventing proximal CRCs and the need to carefully assess the proximal colon during scope procedure.

Sessile serrated adenoma detection rate is correlated with adenoma detection rate

AIM To investigated the association between adenoma detection rate(ADR) and sessile serrated ADR(SSADR) and significant predictors for sessile serrated adenomas(SSA) detection.METHODS This study is a retrospective, single-center analysis. Total colonoscopies performed by the gastroenterologists at the University of Tokyo Hospital between January and December 2014 were retrospectively identified. Polyps were classified as low-grade or high-grade adenoma, cancer, SSA, or SSA with cytological dysplasia, and the prevalence of each type of polyp was investigated. Predictors of adenoma and SSA detection were examined using logistic generalized estimating equation models. The association between ADR and SSADR for each gastroenterologist was investigated by calculating a correlation coefficient weighted by the number of each gastroenterologist's examination.RESULTS A total of 3691 colonoscopies performed by 35 gastroenterologists were assessed. Overall, 978 (26.5%) low-and 84 (2.2%) high-grade adenomas, 81 (2.2%) cancers, 66 (1.8%) SSAs, and 2 (0.1%) SSAs with cytological dysplasia were detected. Overall ADR was 29.5%(men 33.2%, women 23.8%) and overall SSADR was 1.8%(men 1.7%, women 2.1%). In addition, 672 low-grade adenomas (68.8% of all the detected lowgrade adenomas), 58 (69.9%) high-grade adenomas, 29 (34.5%) cancers, 52 (78.8%) SSAs, and 2 (100%) SSAs with cytological dysplasia were found in the proximal colon. Adenoma detection was the only significant predictor of SSA detection (adjusted OR: 2.53, 95%CI: 1.53-4.20; P < 0.001). The correlation coefficient between ADR and SSADR weighted by the number of each gastroenterologist's examinations was 0.606(P < 0.001).CONCLUSION Our results demonstrated that ADR is correlated to SSADR. In addition, patients with adenomas had a higher prevalence of SSAs than those without adenomas.

Sessile serrated adenomas in the proximal colon are likely to be flat,large and occur in smokers

AIM:To examine the epidemiology and the morphology of the proximal sessile serrated adenomas(SSAs).METHODS:We conducted a retrospective study to identify patients with SSAs using a university-based hospital pathology database query from January 2007to April 2011.Data collected included:age,gender,ethnicity,body mass index,diabetes,smoking,family history of colorectal cancer,aspirin,and statin use.We collected data on morphology of SSAs including site(proximal or distal),size,and endoscopic appearance(flat or protuberant).We also compared proximal SSAs to proximal tubular adenomas detected during same time period.RESULTS:One hundred and twenty patients with SSAs were identified:61%were distal and 39%were proximal SSAs.Proximal SSAs were more likely to be flat than distal(100%vs 78%respectively;P=0.0001).Proximal SSAs were more likely to occur in smokers(OR=2.63;95%CI:1.17-5.90;P=0.02)and in patients with family history of colorectal cancer(OR=4.72;95%CI:1.43-15.55;P=0.01)compared to distal.Proximal SSAs were statistically more likely to be≥6 mm in size(OR=2.94;P=0.008),and also more likely to be large(≥1 cm)(OR=4.55;P=0.0005)compared to the distal lesions.Smokers were more likely to have proximal(P=0.02),flat(P=0.01)and large(P=0.007)SSAs compared to non-smokers.Compared to proximal tubular adenomas,proximal SSAs were more likely to be large and occur in smokers.CONCLUSION:Proximal SSAs which accounted for two-fifths of all SSAs were more likely to present as flat lesions,larger SSAs,and were more likely to occur in smokers and in patients with family history of colorectal cancer.Our data has implications for colorectal cancer screening.

Improving sessile serrated adenoma detection rates with high definition colonoscopy:A retrospective study

BACKGROUND Sessile serrated adenomas(SSAs)are important premalignant lesions that are difficult to detect during colonoscopy due to poor definition,concealment by mucous caps,and flat appearance.High definition(HD)colonoscopy may uniquely aid in the detection of these inconspicuous lesions compared to standard definition(SD)colonoscopes.In the absence of existing clinical guidelines to obligate the use of HD colonoscopy for colorectal cancer screening in average-risk patients,demonstrating the benefit of HD colonoscopy on SSA detection rate(SSADR)may help strengthen the evidence to recommend its use in all settings.AIM To evaluate the benefit of HD colonoscopy compared to SD colonoscopy on SSADR in average-risk patients undergoing screening colonoscopy.METHODS Data from screening colonoscopies for patients aged 50-76 years two years before and two years after the transition from SD colonoscopy to HD colonoscopy at our large,academic teaching center were collected.Patients with symptoms of colorectal disease,positive occult blood test,history of colon polyps,cancer,polyposis syndrome,inflammatory bowel disease or family history of colon cancer or polyps were excluded.Patients whose endoscopists did not perform colonoscopies both before and after scope definition change were also excluded.Differences in individual endoscopist SSADR,average SSADR,and overall SSADR with SD colonoscopy vs HD colonoscopy were also evaluated for significance.RESULTS A total of 3657 colonoscopies met eligibility criteria with 2012 colonoscopies from the SD colonoscopy period and 1645 colonoscopies from the HD colonoscopy period from a pool of 11 endoscopists.Statistically significant improvements of 2.30%in mean SSADR and 2.53%in overall SSADR were noted with HD colonoscopy(P=0.00028 and P=0.00849,respectively).On the individual level,three endoscopists experienced statistically significant benefit with HD colonoscopy(+5.74%,P=0.0056;+4.50%,P=0.0278;+4.84%,P=0.03486).CONCLUSION Our study suggests that HD colonoscopy statistically significantly improves sessile serrated adenoma detection rate in the screening of average risk patients during screening colonoscopy.By improving the detection and removal of these lesions,adoption of HD colonoscopy may reduce the significant premalignant burden of sessile serrated adenomas.

Serrated polyps of the colon and rectum:Remove or not?

In recent years,the serrated neoplasia pathway where serrated polyps arise as a colorectal cancer has gained considerable attention as a new carcinogenic pathway.Colorectal serrated polyps are histopathologically classified into hyperplastic polyps(HPs),sessile serrated lesions,and traditional serrated adenomas;in the serrated neoplasia pathway,the latter two are considered to be premalignant.In western countries,all colorectal polyps,including serrated polyps,apart from diminutive rectosigmoid HPs are removed.However,in Asian countries,the treatment strategy for colorectal serrated polyps has remained unestablished.Therefore,in this review,we described the clinicopathological features of colorectal serrated polyps and proposed to remove HPs and sessile serrated lesions≥6 mm in size,and traditional serrated adenomas of any size.

Serrated polyps of the colon and rectum: Endoscopic features including image enhanced endoscopy

In this review, I outline the characteristic endoscopic findings of serrated lesions of the colorectum based on image enhanced endoscopy(IEE). Histopathologically, lesions with serrated structures are typically classified into the following three types based: hyperplastic polyps(HPs), traditional serrated adenomas(TSAs), and sessile serrated adenoma/polyps(SSA/Ps). Both HP and SSA/P often present as dark-green colors on auto fluorescence imaging(AFI) colonoscopy that are similar to the normal surrounding mucosa. In contrast, TSAs often have elevated shapes and present as magenta colors that are similar to the tubular adenomas. The superficial type of TSA also includes many lesions that present as magenta colors. When SSA/Ps are associated with cytological dysplasia, many lesions present with magenta colors, whereas lesions that are not associated with cytological dysplasia present with dark-green colors. When observed via narrow band imaging(NBI), many SSA/P include lesions with strong mucous adhesions. Because these lesions are observed with reddish mucous adhesions, we refer to them as "red cap sign" and place such signs among the typical findings of SSA/P. Because the dilatation of the pit in SSA/P is observed as a round/oval black dot on magnified observations, we refer to this finding as Ⅱ-dilatation pit(Ⅱ-D pit) and also positioned it as a characteristic finding of SSA/P. In contrast, dilatations of the capillary vessels surrounding the glands, such as those that occur in tubular adenoma, are not considered to be useful for differentiating HPs from SSA/Ps. However, in cases in which SSA/P is associated with cytological dysplasia, the dilatation of capillary vessels is observed in the same area. When submucosal layer invasion occurs in the same area, the blood flow presents with irregularities that are similar to those of common colorectal cancer at an early stage and disappears as the invasion proceeds deeply. The surface pattern of invasive cancer that is observed at the tumor surface is also likely to disappear. Based on the above results, we considered that the differentiations between HP and TSA, between TSA and SSA/P, and between HP and SSA/P might become easier due to the concomitant use of white light observation and IEE. We also concluded that AFI and NBI can be useful modalities for SSA/P lesions associated with cytological dysplasia.

Endoscopic diagnosis for colorectal sessile serrated lesions

BACKGROUND Hyperplastic polyps are considered non-neoplastic, whereas sessile serrated lesions(SSLs) are precursors of cancer via the ‘‘serrated neoplastic pathway’’. The clinical features of SSLs are tumor size(> 5 mm), location in the proximal colon, coverage with abundant mucus called the ‘‘mucus cap’’, indistinct borders, and a cloud-like surface. The features in magnifying narrow-band imaging are varicose microvascular vessels and expanded crypt openings. However, accurate diagnosis is often difficult.AIM To develop a diagnostic score system for SSLs.METHODS We retrospectively reviewed consecutive patients who underwent endoscopic resection during colonoscopy at the Toyoshima endoscopy clinic. We collected data on serrated polyps diagnosed by endoscopic or pathological examination. The significant factors for the diagnosis of SSLs were assessed using logistic regression analysis. Each item that was significant in multivariate analysis was assigned 1 point, with the sum of these points defined as the endoscopic SSL diagnosis score. The optimal cut-off value of the endoscopic SSL diagnosis score was determined by receiver-operating characteristic curve analysis.RESULTS Among 1288 polyps that were endoscopically removed, we analyzed 232 diagnosed as serrated polyps by endoscopic or pathological examination. In the univariate analysis, the location(proximal colon), size(> 5 mm), mucus cap, indistinct borders, cloud-like surface, and varicose microvascular vessels were significantly associated with the diagnosis of SSLs. In the multivariate analysis, size(> 5 mm;P = 0.033), mucus cap(P = 0.005), and indistinct borders(P = 0.033) were independently associated with the diagnosis of SSLs. Size > 5 mm, mucus cap, and indistinct borders were assigned 1 point each and the sum of these points was defined as the endoscopic SSL diagnosis score. The receiver-operating characteristic curve analysis showed an optimal cut-off score of 3, which predicted pathological SSLs with 75% sensitivity, 80% specificity, and 78.4% accuracy. The pathological SSL rate for an endoscopic SSL diagnosis score of 3 was significantly higher than that for an endoscopic SSL diagnosis score of 0, 1, or 2(P < 0.001).CONCLUSION Size > 5 mm, mucus cap, and indistinct borders were significant endoscopic features for the diagnosis of SSLs. Serrated polyps with these three features should be removed during colonoscopy.

Evaluation of magnifying colonoscopy in the diagnosis of serrated polyps

AIM:To elucidate the colonoscopic features of serrated lesions of the colorectum using magnifying colonoscopy.METHODS:Broad division of serrated lesions of the colorectum into hyperplastic polyps(HPs),traditional serrated adenomas(TSAs),and sessile serrated adenomas/polyps(SSA/Ps) has been proposed on the basis of recent molecular biological studies.However,few reports have examined the colonoscopic features of these divisions,including magnified colonoscopic findings.This study examined 118 lesions excised in our hospital as suspected serrated lesions after magnified observation between January 2008 and September 2011.Patient characteristics(sex,age),conventional colonoscopic findings(location,size,morphology,color,mucin) and magnified colonoscopic findings(pit pattern diagnosis) were interpreted by five colonoscopists with experience in over 1000 colonoscopies,and were compared with histopathological diagnoses.The pit patterns were categorized according to Kudo's classification,but a more detailed investigation was also performed using the subclassification [type Ⅱ-Open(type Ⅱ-O),type Ⅱ-Long(type Ⅱ-L),or type Ⅳ-Serrated(type Ⅳ-S)] proposed by Kimura T and Yamano H.RESULTS:Lesions comprised 23 HPs(23/118:19.5%),39 TSAs(39/118:33.1%:with cancer in one case),50 SSA/Ps(50/118:42.4%:complicated with cancer in three cases),and six others(6/118:5.1%).We excluded six others,including three regular adenomas,one hamartoma,one inflammatory polyp,and one juvenile polyp for further analysis.Conventional colonoscopy showed that SSA/Ps were characterized as larger in diameter than TSAs and HPs(SSA/P vs HP,13.62 ± 8.62 mm vs 7.74 ± 3.24 mm,P < 0.001;SSA/Ps vs TSA,13.62 ± 8.62 mm vs 9.89 ± 5.73 mm,P < 0.01);common in the right side of the colon [HPs,30.4%(7/23):TSAs,20.5%(8/39):SSA/P,84.0%(42/50),P < 0.001];flat-elevated lesion [HPs,30.4%(7/23):TSAs,5.1%(2/39):SSA/Ps,90.0%(45/50),P < 0.001];normal-colored or pale imucosa [HPs,34.8%(8/23):TSAs,10.3%(4/39):SSA/Ps,80%(40/50),P < 0.001];and with large amounts of mucin [HPs,21.7%(5/23):TSAs,17.9%(7/39):SSA/Ps,72.0%(36/50),P < 0.001].In magnified colonoscopic findings,17 lesions showed either type Ⅱ pit pattern alone or partial type Ⅱ pit pattern as the basic architecture,with 14 HPs(14/17,70.0%) and 3 SSA/Ps.Magnified colonoscopy showed the type Ⅱ-O pit pattern as characteristic of SSA/Ps [sensitivity 83.7%(41/49),specificity 85.7%(54/63)].Cancer was also present in three lesions,in all of which a type Ⅵ pit pattern was also present within the same lesion.There were four HPs and four TSAs each.The type Ⅳ-S pit pattern was characteristic of TSAs [sensitivity 96.7%(30/31),specificity 89.9%(72/81)].Cancer was present in one lesion,in which a type Ⅵ pit pattern was also present within the same lesion.In our study,serrated lesions of the colorectum also possessed the features described in previous reports of conventional colonoscopic findings.The pit pattern diagnosis using magnifying colonoscopy,particularly magnified colonoscopic findings using subclassifications of surface architecture,reflected the pathological characteristics of SSA/Ps and TSAs,and will be useful for colonoscopic diagnosis.CONCLUSION:We suggest that this system could be a good diagnostic tool for SSA/Ps using magnifying colonoscopy.

Case of pediatric traditional serrated adenoma resected via endoscopic submucosal dissection

Traditional serrated adenoma(TSA)is a type of serrated polyp of the colorectum and is thought to be a precancerous lesion.There are three types of serrated polyps,namely,hyperplastic polyps,sessile serrated adenomas/polyps,and TSAs.TSA is the least common of the three types and accounts for about 5% of serrated polyps.Here we report a pediatric case of TSA that was successfully resected by endoscopic submucosal dissection(ESD).This rare case report describes a pediatric patient with no family history of colonic polyp who was admitted to our hospital with hematochezia.On colonoscopy,we found a polypoid lesion measuring 10 mm in diameter in the lower rectum.We selected ESD as a surgical option for en bloc resection,and histopathological examination revealed TSA.The findings in this case suggest that TSA with precancerous potential can occur in children,and that ESD is useful for treating this lesion.

Correlations of morphology and molecular alterations in traditional serrated adenoma

Traditional serrated adenoma was first reported by Longacre and FenoglioPresier in 1990.Their initial study described main features of this lesion,but the consensus diagnostic criteria were not widely adopted until recently.Traditional serrated adenoma presents with grossly protuberant configuration and pineconelike appearance upon endoscopy.Histologically,it is characterized by ectopic crypt formation,slit-like serration,eosinophilic cytoplasm and pencillate nuclei.Although much is now known about the morphology and molecular changes,the mechanisms underlying the morphological alterations are still not fully understood.Furthermore,the origin of traditional serrated adenoma is not completely known.We review recent studies of the traditional serrated adenoma and provide an overview on current understanding of this rare entity.

From traditional serrated adenoma to tubulovillous adenoma and beyond

It is well established that colorectal cancer develops from a series of precursor epithelial polyps, including tubular adenomas, villous/tubulovillous adenomas (VA/TVA), sessile serrated adenomas (SSA) and traditional serrated adenomas (TSA). Of these, TSAs are least common and account for only 5% of all serrated polyps. TSAs are characterised by the presence of a &ldquo;pinecone-like&rdquo; architecture, granular eosinophilic cytoplasm, luminal serrations, ectopic crypt foci (ECF) and elongated, pencillate nuclei. However, the distinct slit-like luminal serrations, reminiscent of small bowel mucosa, appear to be the most unique and reproducible feature to distinguish TSAs from other polyps. There is a contention that TSAs are not inherently dysplastic and that the majority do not show cytological atypia. Two types of dysplasia are associated with TSA. Serrated dysplasia is less well recognised and less commonly encountered than adenomatous dysplasia. In addition, it is now becoming increasingly evident that TSAs can be admixed with HP, SSA and VA/TVA. At a genetic level, polyps may switch phenotype as they accumulate genetic changes, evolving from a serrated pathway to a more conventional one, which could be the basis for a spectrum theory starting out with a TSA with serration and ECF evolving into a TSA with conventional dysplasia and, eventually, to a well-developed conventional adenoma. Nevertheless, there is an exigency for future studies to provide further illumination and bridge the gaps in our present understanding.

Cold snare polypectomy:A closer look at the efficacy and limitations for polyps 10-20 mm in size

Current guidelines recommend cold snare polypectomy for polyps less than 10 mm in size.Conversely,endoscopic mucosal resection is still the preferred technique for larger polyps.Concerns regarding cold snare polypectomy for larger polyps revolve around the difficulty in conducting en-bloc resection(resulting in piecemeal removal),and the potential for local residual polyp tissue and a high rate of recurrence.On the other hand,cold snare technique has the advantages of shortening procedure time,reducing delayed bleeding risks and lowering cost of treatment.Numerous ongoing and recent studies are focused on evaluating the risks and benefits of this technique for polyps larger than 10 mm,with the goal of providing clear guidelines in the near future.The aim of this editorial is to provide our readers with an overview regarding this subject and the latest developments surrounding it.

Heterogeneity of colorectal adenomas, the serrated adenoma, and implications for screening and surveillance

Current algorithms for screening and surveillance for colon cancer are valuable, but may be limited by the underlying nature of the targeted neoplastic lesions. Although part of the success of adenoma removal relates to interruption of so-called "adenoma-carcinoma sequence", an alternate serrated pathway to colon cancer may pose difficulties with the ultimate results achieved by traditional colonoscopic methods. The endpoint carcinoma in this unique pathway may be derived from a dysplastic serrated adenoma. These tend to be located primarily in the right colon, especially in females, and are frequently associated with co-existent colon cancer. Unfortunately, however, there are few, if any, other identifiable risk factors, including age or family history of colon polyps or colon cancer. Moreover, this alternate serrated pathway may itself also be quite biologically heterogeneous as reflected in sessile serrated adenomas (SSA) with virtually exclusive molecular signatures defined by the presence of either BRAF or KRAS mutations. Screening algorithms in the future may need to be modified and individualized, depending on new information that likely will emerge on the natural history of these biologically heterogeneous lesions that differs from traditional adenomatous polyps.

Clinico-pathological aspects of colorectal serrated adenomas

AIM： To study the association of colorectal serrated adenomas （SAs） with invasive carcinoma, local recurrence, synchronicity and metachronicity of lesions. METHODS： A total of 4536 polyps from 1096 patients over an eight-year period （1987-1995） were retrospectively examined. Adenomas showing at least 50% of serrated architecture were called SAs by three reviewing pathologists. RESULTS： Ninety-one （2%） of all polyps were called SAs, which were found in 46 patients. Invasive carcinomas were seen in 3 out of 46 （6.4%） patients, of whom one was a case of familial adenomatous polyposis （FAP）. A male preponderance was noted and features of a mild degree of dysplasia were seen in majority （n=75, 83%） of serrated adenomas. Follow-up ranged 1-12 years with a mean time of 5.75 years. Recurrences of SAs were seen in 3 （6.4%） cases, synchronous SAs in 16 （34.8%） cases and metachronous SAs in 9 （19.6%） cases. CONCLUSION： Invasive carcinoma arising in serrated adenoma is rare, accounting for 2 （4.3%） cases studied in this series.