Introduction

Sessile serrated lesion (SSL), is a precursor lesion in the serrated neoplasia pathway [1]. These lesions are considered a major contributor to the failure of colonoscopy to prevent colorectal cancers (known as “interval cancer” or “post-colonoscopy colorectal cancer”) [2]. Therefore, improved awareness of the clinicopathological and endoscopic characteristics of SSL and their dysplastic components is important.

Aims & Methods

This study aimed to elucidate the clinicopathological and endoscopic features of SSLs with and without dysplasia or carcinoma. We reviewed the data of all colorectal lesions that were pathologically diagnosed as SSLs at Juntendo University Hospital, Tokyo, Japan, between 2011 and 2022. During this period, all suspected SSLs were resected endoscopically or surgically. The histological diagnosis of SSLs was based on the World Health Organization Classification of Tumours of the Digestive System 2019 [3]. We analysed the clinicopathological features of all the patients, including age, sex, tumour location and size, and conventional endoscopic findings.

Results

Table 1.	Clinicopathological and endoscopic characteristics of colorectal lesions studied.
Variable [Lesions / Patients]	ND [1972 (92.5%) / 1276]	LGD [101 (4.7%) / 94]	HGD [39 (1.8%) / 38]	SIC [20 (0.9%) / 20]
Age (years)	62.8 ± 12.1 (23 - 91)	64.8 ± 10.0 (35 - 85)	71.6 ± 8.9 (51 - 86)	72.2 ± 9.7 (47 - 90)
Sex: Male / Female	667 (52.3%) / 609 (47.7%)	41 (43.6%) / 53 (56.4%)	14 (36.8%) / 24 (63.2%)	7 (35.0%) / 13 (65.0%)
Location: Proximal / Distal	1637 (83.0%) / 335 (17.0%)	81 (80.2%) / 20 (19.8%)	33 (84.6%) / 6 (15.4%)	18 (90.0%) / 2 (10.0%)
Size of tumour (mm)	10.8 ± 7.6 (2 - 65)	15.0 ± 9.0 (5 - 42)	14.2 ± 8.4 (6 - 43)	20.2 ± 12.7 (8 - 65)
(Semi)pedunculated morphology	51 (2.6%)	14 (13.9%)	10 (25.6%)	5 (25.0%)
Reddishness	77 (3.9%)	40 (39.6%)	21 (53.8%)	16 (80.0%)
Double elevation	70 (3.5%)	61 (60.4%)	19 (48.7%)	10 (50.0%)
Central depression	44 (2.2%)	6 (5.9%)	2 (5.1%)	6 (30.0%)

The clinicopathological and endoscopic characteristics of the lesions are summarised in Table 1. Out of 2132 SSLs (1368 patients), 1972 (92.5%) had no dysplasia (ND), 101 (4.7%) had low-grade dysplasia (LGD), 39 (1.8%) had high-grade dysplasia (HGD), and 20 (0.9%) had submucosal invasive carcinoma (SIC). Older age is more frequently associated with SSLs and dysplasia/carcinoma. The most frequent location of tumours was the proximal colon. A stepwise increase in the size of the SSL series was identified, along with dysplastic progression from ND to dysplasia to invasive carcinoma. Similarly, larger lesions were associated with higher rates of dysplasia or cancer (≥ 5 mm, 1.2%; 6 - 10 mm, 6.5%; 11-15 mm; 9.5%, 16-20 mm, 12.9%; ≥ 21 mm, 17.3%). However, 66 of the 160 (41.3%) SSLs with dysplasia/carcinoma were ≤ 10 mm in size. Macroscopically, (semi)pedunculated morphology, reddishness, double elevation, and central depression were more frequently observed in SSLs with dysplasia/carcinoma than in those without.

Conclusion

Our findings suggest that SSLs with dysplasia/carcinoma may be more frequently associated with older age, the proximal colon, and larger lesions. However, dysplasia/cancer could coexist in SSLs even if the size was ≤ 10 mm. Additionally, in an SSL series, endoscopic characteristics, including (semi)pedunculated morphology, reddishness, double elevation, and central depression, might be useful for the accurate diagnosis of advanced histology within an SSL. These results may may contribute to improvement in the recognition and complete resection of SSLs with dysplasia or invasive carcinoma, thereby reducing the rates of colorectal cancer.

References

1. O'Brien MJ, Yang S, Mack C, et al. Comparison of microsatellite instability, CpG island methylation phenotype, BRAF and KRAS status in serrated polyps and traditional adenomas indicates separate pathways to distinct colorectal carcinoma end points. Am J Surg Pathol. 2006; 30: 1491–1501.
2. Sawhney MS, Farrar WD, Gudiseva S, et al. Microsatellite instability in interval colon cancers. Gastroenterology. 2006; 131: 1700–1705.
3. Pai RK, Mäkinen MJ, Rosty C. Colorectal serrated lesions and polyps. In: Nagtegaal ID, Arends MJ, Odze RD, Lam AK (eds). WHO Classification of Tumours of the Digestive System, 5^th edn. Lyon: IARC Press, 2019; 163–169.

Introduction

Sessile serrated lesions with dysplasia (SSLD) are known high-risk polyps due to their potential for rapid progression to colorectal cancer (CRC). As such, timely detection and appropriate treatment are essential. However, due to the fact that SSLDs are relatively rare, evidence regarding their prevalence and characteristics remains limited. This population-based study aims to generate more robust evidence on the prevalence and characteristics of SSLDs.

Aims & Methods

This study analyzed all prospectively collected baseline colonoscopy data from the Dutch CRC screening program between January 2014 and December 2023, linked to the national pathology database (PALGA). The prevalence of sessile serrated lesions (SSL) and SSLD was calculated for two time periods (2014-2018 and 2019-2023), along with the number needed to screen (NNS) and corresponding confidence intervals (CI), stratified by age category (<60, 60-70, >70) and gender. Dysplasia rates (the proportion of SSLD among all SSL diagnoses) were assessed by polyp characteristics- including location, age- and size category- as well as by colonoscopy year to evaluate temporal trends. Multivariate regression using generalized estimating equations (GEE) was performed to examine the influence of age and gender on SSLD prevalence, and to identify polyp-level characteristics associated with dysplasia.

Results

Among 516.193 colonoscopies, 49.953 individuals had at least one SSL, and 5.737 individuals had at least one SSLD. Over the study period, a total 1.033.298 polyps were removed, including 76.771 SSLs and 7.019 SSLDs. Among FIT-positive individuals the overall SSL prevalence 9.68% (9.60-9.76) and the overall SSLD prevalence was 1.11% (1.08-1.14). The NNS for SSLs decreased from 13 in 2014-2018 to 9 in 2019-2023, while the NNS for SSLDs remained stable at 90. At patient level, increasing age was associated with higher SSLD prevalence (OR 1.03 CI95% 1.03-1.04 per year increase). At polyp level, both increasing age and size of SSLs were associated with a higher rate of dysplasia (P<0.001), yet at least 30% of SSLD cases involved polyps <10 mm. Regression analysis combining size and age showed that, compared to SSLs <5mm in individuals aged ≤60 years, the odds of dysplasia were seven times higher in individuals aged >70 years with SSLs ≥25mm (OR 7.01 CI95% 3.81-12.5). Over time, the dysplasia rate among SSLs declined from 17.5% in 2014 to 6.6% in 2023 (table 1).

Table 1: Diagnoses of SSL versus SSL and overall rate of dysplasia over time

	2014	2015	2016	2017	2018	2019	2020	2021	2022	2023
SSLs (n)	1.867	4.467	5.866	7.009	8.202	8.901	6.788	11.148	10.645	11.878
SSLD (n)	326	600	550	857	890	825	521	909	747	785
Rate of dyspl​asia:	17.5%	13.4%	9.4%	12.2%	10.9%	9.3%	7.7%	8.2%	7.0%	6.6%

Conclusion

This national study demonstrated that the prevalence for SSLs increased over time, while the prevalence of SSLD remained stable. Dysplasia in SSLs was associated with older age and larger polyp size. The observed decline in dysplasia rates over time may reflect challenges in SSLD detection, possibly due to limited classification guidelines compared to SSLs. Further research is needed to support improved recognition of SSLDs by both endoscopists and pathologists.

Disclosure

ED: received honoraria for consultancy from Olympus, Fujifilm, Ambu, InterVenn, Norgine and Exact Sciences. Speakers' fees from Olympus, Norgine, IPSEN/Mayoly, FujiFilm, Steris and Pentax. Endoscopic equipment on loan of FujiFilm
All other authors (NR and JIJ, VA) have nothing to disclose.

Introduction

Sessile serrated lesions (SSLs) are obscured lesions predominantly at right sided colon and associated with interval colorectal cancer. However, the prevalence and risk factors among younger individuals remain unclear.

Aims & Methods

This retrospective study enrolled individuals who underwent index colonoscopy. The primary outcomes were SSL prevalence between younger (<50 years) and older (≥50 years) groups, whereas the secondary outcomes included clinically significant serrated polyps (CSSPs). Multivariable logistic regression was employed to identify predictors. The aim of this study is to investigate the prevalence of SSL of younger age people in the single center cohort. ​Individuals who visited outpatient services were mostly symptomatic, were eligible for screening colonoscopy, or had abnormal fecal/tumor marker test results. Additionally, asymptomatic individuals who underwent health checkups at their own expense or who adhered to national labor law requirements were included. The exclusion criteria were as follows: (1) instances of duplicated cases due to prior colonoscopy examinations, (2) cases with inadequate bowel preparation, (3) history of hospitalization or colonoscopy as part of an emergency room visit, (4) cases of unsuccessful cecal intubation or flexible sigmoidoscopy, and (5) suspicious or confirmed inflammatory bowel disease. Notably, individuals who had previously undergone colonoscopy at other hospitals, as confirmed by their electronic medical records or chart review, were also excluded.

Results

Of the 9854 eligible individuals, 4712 (47.8%) were categorized into the younger age group. Individuals in the younger age group exhibited a lower prevalence of adenomas (22.6% vs. 46.2%, P < 0.001) and right-sided adenomas (11.2% vs. 27.2%, P < 0.001) compared with their older counterparts. However, both groups exhibited a similar prevalence of SSLs (7.2% vs. 6.5%, P = 0.157) and CSSP (10.3% vs. 10.3%, P = 0.956). Multivariable analysis results revealed that age = 40–49 years (odds ratio [OR] = 1.81, 95% confidence interval [CI] = 1.01–3.23), longer withdrawal time (OR = 1.18, 95% CI = 1.15 – 1.21 per minute increment), and endoscopist performance (OR = 3.35, 95% CI = 2.44 – 4.58) were independent predictors of SSL detection in the younger age group. No significant correlation was observed between adenoma and SSL detection rates among endoscopists (P = 0.083).

	Younger age group (< 50-years-old)	Elder age group (≥ 50-years-old)	P value
Cases (%)	4712 (47.8)	5142 (52.1)	Not applicable
Symptomatic cases (%)	1985 (42.1)	2763 (53.7)	< 0.001*
Sex (female, %)	2425 (51.5)	2649 (51.5)	< 0.001*
Family history of CRC (%)	318 (6.7)	164 (3.2)	< 0.001*
Adenoma (%)	1063 (22.6)	2375 (46.2)	< 0.001*
Advanced adenoma (%)	188 (4.0)	728 (14.2)	< 0.001*
SSL (%)	341 (7.2)	335 (6.5)	0.157
CSSP (%)	485 (10.3)	531 (10.3)	0.956
CRC (%)	19 (0.4)	72 (1.4)	< 0.001*

Conclusion

SSLs are not uncommon among younger individuals. Moreover, diligent effort and expertise are of paramount importance in SSL detection. Future studies should explore the clinical significance of SSLs in younger age individuals.

References

1. Murcia O, Juárez M, Hernández-Illán E et al. Serrated colorectal cancer: Molecular classification, prognosis, and response to chemotherapy. World J Gastroenterol 2016; 22: 3516-3530. doi:10.3748/wjg.v22.i13.3516
2. Meester RG, van Herk MM, Lansdorp-Vogelaar I et al. Prevalence and clinical features of sessile serrated polyps: a systematic review. Gastroenterology 2020; 159: 105-118. e125
3. Burnett-Hartman AN, Newcomb PA, Phipps AI et al. Colorectal endoscopy, advanced adenomas, and sessile serrated polyps: implications for proximal colon cancer. The American journal of gastroenterology 2012; 107: 1213-1219. doi:10.1038/ajg.2012.167
4. Zorzi M, Senore C, Da Re F et al. Detection rate and predictive factors of sessile serrated polyps in an organised colorectal cancer screening programme with immunochemical faecal occult blood test: the EQuIPE study (Evaluating Quality Indicators of the Performance of Endoscopy). Gut 2017; 66: 1233-1240
5. Lall V, Ismail AGM, Ayonrinde OT. Disparate age and sex distribution of sessile serrated lesions and conventional adenomas in an outpatient colonoscopy population–implications for colorectal cancer screening? International Journal of Colorectal Disease 2022; 37: 1569-1579
6. Kim HY, Kim SM, Seo J-H et al. Age-specific prevalence of serrated lesions and their subtypes by screening colonoscopy: a retrospective study. BMC Gastroenterology 2014; 14: 82. doi:10.1186/1471-230X-14-82

Disclosure

This study is recently accepted by Endoscopy (2024/02). We hope this research can be considered for the congress with its clinical importance and impact.

Introduction

Differentiating between colorectal serrated polyps (SPs) on endoscopy can be challenging since sessile serrated lesions (SSLs) and hyperplastic polyps (HPs) tend to have a similar appearance^1-4. Furthermore, the endoscopic differences between the two subtypes of HPs, namely microvesicular HP (MVHP) and goblet cell-rich HP (GCHP), are not well understood^5,6. Therefore, we compared the endoscopic features of SSL, MVHP, and GCHP.

Aims & Methods

This retrospective, cross-sectional study was conducted at the Toyoshima Endoscopy Clinic. We examined the polyp size, location, Paris classification type, mucus cap, indistinct border, expanded crypt opening, varicose microvascular vessels (VMV), and Japan NBI expert team (JNET) classification type. Multivariable analysis was performed to determine the endoscopic finding that predicted SP histology using a binomial logistic regression model. We constructed endoscopic microvesicular goblet (MG) score for differentiating SPs using the endoscopic findings associated with SP histology in the multivariable analysis, and calculated the area under the receiver operating characteristic curve (AUC) and diagnostic accuracy.

Results

A total of 1366 SPs were eligible for this study, including 321 SSLs, 718 MVHPs, and 327 GCHPs. The mean polyp size was 6.24 mm. SPs in the proximal colon accounted for 70.7%. In the comparison between MVHP and GCHP, a mucus cap (partial regression coefficient 1.44, 95% confidence interval [CI] 1.06-1.82), expanded crypt opening (1.92, 1.44-2.40), and VMV (1.04, 0.58-1.49) were more often found in MVHP in contrast to GCHP (Table). comparison of SSL and MVHP showed that SSLs were located in the proximal colon (0.70, 0.30-1.10), were larger (0.21, 0.16-0.25), and had mucus cap (0.54, 0.16-0.93) compared to MVHPs. On comparing the SSL plus MVHP group and GCHP group, larger size (0.12, 0.06-0.19), a mucus cap (1.76, 1.39-2.14), expanded crypt opening (2.04, 1.57-2.52), VMV (1.21, 0.75-1.68), and JNET type 2A (1.17, 0.73-1.61) were more often observed in SSL + MVHP group compared with GCHP. Mucus cap, expanded crypt opening, and VMV were each assigned 1 point and the sum of the points was defined as the endoscopic MG score. In the examination of MVHPs and GCHPs, the AUC of the endoscopic MG score for predicting MVHP was 0.78 (95% CI 0.76-0.81) and the optimal cut-off value was 1; the sensitivity, specificity, and positive predictive value (PPV) were 74.7%, 75.5%, 87.0%, respectively. In the assessment of SSLs, MVHPs, and GCHPs, the AUC of the endoscopic MG score for predicting SSL plus MVHP group was 0.82 (0.79-0.84) and the optimal cut-off value was 1; the sensitivity, specificity, and PPV were 79.4%, 75.5%, and 91.2%, respectively.

Table. Multivariable analysis for comparison of endoscopic appearance between MVHP and GCHP.
	Partial regression coefficient	95% confidence interval	Degree of freedom	P value
Polyp size	0.04	-0.03, 0.11	1	0.23
Mucus cap	1.44	1.06, 1.82	1	<0.001
Indistinct border	0.07	-0.32, 0.46	1	0.73
Expanded crypt opening	1.92	1.44, 2.40	1	<0.001
VMV	1.04	0.58, 1.49	1	<0.001

Conclusion

MVHP and GCHP, while belonging to the same HP category, exhibited different endoscopic appearances such as mucus cap, expanded crypt opening, and VMV. Conversely, SSL and MVHP despite belonging to different histopathological categories, showed similar endoscopic appearances except for mucus cap. Moreover, SSL plus MVHP showed distinct endoscopic appearances compared to GCHP group. Considering MVHP and GCHP as separate entities can aid in the endoscopic diagnosis of SPs.

References

1. Ijspeert JEG, de Wit K, van der Vlugt M, et al. Prevalence, distribution and risk of sessile serrated adenomas/polyps at a center with a high adenoma detection rate and experienced pathologists. Endoscopy. 2016;48(08):740-746.
2. Turner KO, Genta RM, Sonnenberg A. Lesions of All Types Exist in Colon Polyps of All Sizes. Am J Gastroenterol. 2018;113(2):303-306.
3. Zessner-Spitzenberg J, Waldmann E, Jiricka L, et al. Comparison of adenoma detection rate and proximal serrated polyp detection rate and their effect on post-colonoscopy colorectal cancer mortality in screening patients. Endoscopy. 2023;55(5):434-441.
4. Nishizawa T, Yoshida S, Toyoshima A, et al. Endoscopic diagnosis for colorectal sessile serrated lesions. World J Gastroenterol. 2021;27(13):1321-1329.
5. Qazi TM, O'Brien MJ, Farraye FA, et al, 3rd. Epidemiology of goblet cell and microvesicular hyperplastic polyps. Am J Gastroenterol. 2014;109(12):1922-1932.
6. Crockett SD, Barry EL, Mott LA, et l. Predictors of Incident Serrated Polyps: Results from a Large Multicenter Clinical Trial. Cancer Epidemiol Biomarkers Prev. 2022;31(5):1058-1067.

Disclosure

The authors have no COI.

Introduction

Sessile Serrated Lesions (SSLs) show an “ultra flat” morphology, a mucus cap and are predominantly located proximally to the splenic flexure (PSF) (1). Hypothetically, previous knowledge in detection of flat or non-protruding conventional adenoma could be a predictor factor for endoscopic detection of SSLs.

Aims & Methods

Aim: To investigate in a South American Private Hospital, the relationship between Flat Adenomas Detection Rate (FADR) and Sessile Serrate Lesion Detection Rate (SDR)
Methods: This study is a retrospective, single-center analysis carried out at Centro Medico Docente La Trinidad Caracas-Venezuela from total selected colonoscopies performed by the gastroenterologists between 2008 and 2018 in patients 51-80 years old (YO). For this study, Adenoma Detection Rate (ADR) includes the whole morphologic spectrum of colon & rectum traditional adenomas from Paris Classification of Colorectal Lesions (2). We will consider the “General ADR” as “GADR”, including Non-protruding or flat ADR: “FADR” plus Protruding ADR: “PADR”, as well as the last two separately. By using logistic regression generalized estimating equation models, the location in colon & rectum and morphology of all types of adenomas (ADs) were assessed. The relationship between the global number of colonoscopies (GNC), GADR, FADR, PADR and the SDR was investigated calculating a correlation coefficient (CC) weighted by the number of total colonoscopies. In addition, 3 linear regression equation models to estimate the relationship between the 3 different types of ADR and SDR and the probability of occurrence of SDR based on the proportion of colonoscopies with SDR presenting every type of ADR weighted by the number of colonoscopies with SDR were calculated.

Results

Results of the linear regression models used to estimate the relationship between the different types of ADR and SDR and the probability of occurrence based on the number of Centro Medico Docente La Trinidad colonoscopies
Category of ADR	R2	β	P	SDR Correlation coefficient	Probability of occurrence (%)	Colonoscopies in each category of ADR validated for SDR calculation
General ADR	0.9687	0.1632	<0.001	0.9842	94.26	148
Flat ADR	0.759	1.888	0.002	0.8712	92.35	145
Protruding ADR	0.3186	0.1664	0.113	0.5644	37.58	59
R2 : Determination coefficient. This evaluates the strength of the linear relationship between the two variables.
β: Partial regression coefficient. It indicates the average effect that the increase in one unit of the predictor variable has on the dependent variable.
ADR: Adenoma Detection Rate. SDR: Serrated Detection Rate. 157 colonoscopies were valid for the calculation of the SDR

For this study, 8432 colonoscopies were validated for 9 gastroenterologists (G1-G9). For patients between 51 and 80 YO, GADR for all 9 Gastroenterologists was 19.76%. GADR-SDR individually for 9 gastroenterologists (G1-G9) varies from as high as G9 GADR-SDR: 33.21%-4.19% to as low as G1: 12.67%-0.50%. The most frequent location for ADs was PSF: OR 1.95, IC 95% (1.30-2.84), P<0.001. SSLs were mostly located PSF OR 2.18, IC 95% (1.44, 2.92) P<0.001. The morphology of ADs was mainly pedicle OR 1.00 IC 95% P<0.001 and for SSL it was flat by far: OR 6.84 IC 95% (2.08-9.02) P<0.001. The CC demonstrated a good association between GADR and SDR: 0.98 P<0.05; and for FADR: 0.87, P<0.05 but not for PADR: 0.56 P=0.113. The GNC was not associated with the SDR CC: -0.197, P=0.6117. The GADR and FADR show robust strength of the linear relationship with SDR and probability of occurrence, but not for PADR (table)

Conclusion

A sine qua non factor for a good SDR for the gastroenterologist is previous knowledge about “FADR”. To the best of our knowledge, this is the first time that ADR has been divided into “General, Flat and Protruded” in order to investigate the impact of the endoscopic skills on flat colorectal lesions detection for a good SDR.

References

1. Rex DK, Ahnen DJ, Baron JA et al. Serrated lesions of the colorectum: review and recommendations from an expert panel. Am J Gastroenterol 2012; 107: 1315-1329; quiz 1314, 1330 [PMID: 22710576 DOI: 10.1038/ ajg.2012.161]
2. Lambert R et al. Superficial Neoplastic Lesions in the Digestive Tract. Endoscopy 2005; 37: 570±578

Introduction

Multiple pathways have been proposed to explain the development of colorectal cancer. The first is the well-established adenoma–carcinoma sequence, in which polypoid adenomas gradually progress to early polypoid cancers and eventually to advanced carcinomas. The second is the serrated pathway, where serrated lesions evolve into early cancers. The third is the de novo pathway, which hypothesizes that carcinomas arise directly from normal epithelium without a pre-existing adenomatous stage. This study focuses on the depressed-type colorectal cancers, which are thought to develop through the de novo pathway, and aims to elucidate their distinct clinicopathological features.

Aims & Methods

From April 2001 to December 2023, a total of 50,119 colorectal neoplasms (excluding advanced cancers) were resected either endoscopically or surgically at Showa University Northern Yokohama Hospital. Among them, 1,633 lesions were identified as T1 carcinomas. Based on macroscopic growth patterns, these T1 cancers were classified into three categories: depressed-type (n = 323; 20.1%), flat-type (n = 602; 36.9%), and protruded-type (n = 703; 43.0%). We compared the pathological characteristics and recurrence rates among the three groups.

Results

The mean tumor size was 15 mm in depressed-type lesions, 32 mm in flat-type, and 18 mm in protruded-type. Vascular invasion was significantly more frequent in the depressed-type group (42%) compared to both flat- and protruded-type lesions (21% each). The proportion of poorly differentiated or mucinous adenocarcinoma was also higher in the depressed type (14%) compared to flat (10%) and protruded types (15%). In contrast, the prevalence of adenomatous components was markedly lower in the depressed type (4%) than in the flat (54%) and protruded types (52%). Similarly, the frequency of polypoid morphology was only 13% in depressed lesions, compared to 56% and 88% in flat and protruded types, respectively. These findings suggest that depressed-type lesions may arise directly from normal epithelium, bypassing the adenomatous phase. The overall rate of distant metastasis or recurrence among all T1 cancers was low, at 0.8% (13 out of 1,633 cases).

Conclusion

Depressed-type colorectal carcinomas are characterized by significantly smaller tumor size and a lower prevalence of adenomatous components, yet exhibit a higher rate of vascular invasion and unfavorable histological features compared to flat and protruded types. These clinicopathological features support the hypothesis that depressed-type carcinomas follow a de novo pathway of tumorigenesis. Given their subtle appearance and high malignant potential, these lesions may be overlooked during routine colonoscopy. Therefore, careful attention should be paid to their morphological features during endoscopic examination to ensure early detection and appropriate management.

Introduction

Magnifying endoscopy (ME) enables clear visualization of microvascular (MV) architecture and microsurface structure [1] [2] and allows real-time visualization of red blood cell flow within subepithelial microvessels. Mean MV blood flow velocity is significantly lower in early gastric cancer than in non-neoplastic lesions [3]. However, MV blood flow velocity in the colorectum has not been investigated and it is unclear whether it is useful for the qualitative diagnosis of colorectal polyps in clinical practice.

Aims & Methods

We aimed to calculate the blood flow velocity in colorectal polyps and the surrounding mucosa, and evaluate its usefulness for the differential diagnosis of colorectal polyps. We retrospectively reviewed videos of colorectal polyps that were endoscopically resected at our hospital between March 2019 and January 2023. All procedures were carried out with a high-resolution optical magnifying endoscope (EC-L600ZP7; Fujifilm Corporation, Tokyo, Japan) and endoscope video system (LASEREO; Fujifilm Corporation). The blood flow velocities of each lesion and surrounding mucosa were carefully evaluated using magnifying blue laser imaging (M-BLI) prior to endoscopic resection. All M-BLI video images were split into 30 fps, and mean blood flow velocities were calculated by the mean movement distance of one tagged red blood cell using split images of videos. We compared mean MV blood flow velocities between lesions and the surrounding mucosa. Furthermore, we calculated the MV blood flow imaging ratio (inside lesion/surrounding mucosa) to avoid the influence of individual differences such as blood pressure.

Results

Adenomas				Hyperplastic polyps
	Blood flow velocity (mm/sec)		(A) / (B)		Blood flow velocity (mm/sec)		(C) / (D)
	(A) Lesions	(B) The surrounding mucosa			(C) Lesions	(D) The surrounding mucosa
mean±SD	1.65±0.66	4.12±1.11	0.41±0.16	mean±SD	2.83±1.10	3.13±0.85	0.89±0.25
(range)	（0.46-2.90）	（1.80-6.20）	（0.1-0.82）	(range)	（1.07-4.50）	（2.30-5.07）	（0.46-1.51）

This study included 30 adenomas (ADs) from 20 patients and 20 hyperplastic polyps (HPs) from 13 patients. No significant differences in age or sex were found between lesion groups. The mean size for ADs and HPs were 4.8 ± 3.1 mm and 3.6 ± 1.8 mm, respectively. The macroscopic type of ADs and HPs were 1 and 0 of 0-Isp, 20 and 13 of 0-Is, and 9 and 7 of 0-IIa, respectively. The mean MV blood flow velocity was significantly lower in ADs (1.65 ± 0.66 mm/sec; range 0.46–2.90) than HPs (2.83 ± 1.10 mm/sec; range 1.07–4.50) or the surrounding mucosa (4.12 ± 1.11 mm/sec; range 1.80–6.20; p < 0.001, respectively). The ratio of the blood flow velocity of lesions compared to the surrounding mucosa was significantly lower in ADs (0.41 ± 0.16; range 0.10–0.82) than HPs (0.89 ± 0.25; range 0.46 – 1.51; p < 0.001).
In summary, MV blood flow velocity was significantly lower in ADs than HPs and the surrounding non-neoplastic mucosa, suggesting blood flow in ADs may be congested. A lower subepithelial MV blood flow rate in ADs compared with non-neoplastic lesions may be due to a difference in caliber and tortuosity of microvessels.

Conclusion

Our results suggest using MV blood flow velocity and ME as a novel dynamic diagnosis for the differential diagnosis of ADs and HPs. However, since this was a single-center retrospective study with a small sample size, further investigation is needed to validate our results and confirm their clinical usefulness.

References

1. Gono, K., et al., J Biomed Opt, 2004. 9(3): p. 568-77.
2. Yoshida, N., et al., J Gastroenterol, 2014. 49(1): p. 73-80.
3. Ueyama, H., et al., J Gastroenterol Hepatol, 2021. 36(7): p. 1927-1934.