Endoscopic treatment and management of rectal neuroendocrine tumors less than 10 mm in diameter

Rectal neuroendocrine tumors(rNETs)measuring less than 10 mm in diameter are defined as small rNETs.Due to the low risk of distant invasion and metastasis,endoscopic treatments,including modified endoscopic mucosal resection,endoscopic submucosal dissection,and other transanal surgical procedures,are effective.This review article proposes a follow-up plan according to the size and histopathology of the tumor after operation.

Colon and rectal cancer:An emergent public health problem

Colorectal cancer ranks third globally,with a high mortality rate.In the United States,and different countries in Europe,organized population screenings exist and include people between 50 and 74 years of age.These screenings have allowed an early diagnosis and consequently an improvement in health indicators.Colon and rectal cancer(CRC)is a disease of particular interest due to the high global burden associated with it and the role attributed to prevention and early diagnosis in reducing morbidity and mortality.This study is a review of CRC pathology and includes the most recent scientific evidence regarding this pathology,as well as a diagnosis of the epidemiological situation of CRC.Finally,the recommendation from a public health perspective will be discussed in detail taking into account the context and the most current recommendations.

Is lymphatic invasion of microrectal neuroendocrine tumors an incidental event?:A case report

BACKGROUND A rectal neuroendocrine tumor(rNET)is a malignant tumor originating from neuroendocrine cells.Currently,tumor size is the primary basis for assessing tumor risk.CASE SUMMARY This article reports the case of a 46-year-old male patient who underwent a colonoscopy that found a 3 mm rectal polypoid bulge.The pathological examination of a sample collected with biopsy forceps revealed a neuroendocrine tumor.Further endoscopic submucosal dissection rescue therapy was used.The presence of lymphatic vessels indicated that the tumor had infiltrated the negative resection margin.The lesion was located in the distal rectum near the anal canal.Therefore,to ensure the patient’s quality of life,follow-up observation was conducted after full communication with the patient.No tumor recurrence or distant metastasis has been found during the 13-mo follow-up after surgery.CONCLUSION Despite the presence of lymphatic invasion and extremely small diameter rNETs in our case,this phenomenon may not imply a higher risk of distant lymph node and organ metastasis.

Rectal Endometriosis Revealed by a Colonic Tumor Obstruction: A Case Report

Endometriosis is defined as the presence of endometrial tissue that is located outside the uterine cavity, associated with fibrosis and inflammatory reaction. The most common atypical locations are the gastrointestinal tract, urinary tract, lung, as well as abdominal surgical scars. Its diagnosis is still very difficult, especially when it manifests itself as an acute large bowel obstruction. We report the rare case of a 41-year-old patient diagnosed with acute colonic obstruction following a rectal tumor. She had undergone colonostomy even though colonoscopy biopsies were nonspecific, and a computed tomography (CT) scan was requested. It showed an adnexal heterogenous mass, therefore the patient had a laparotomy and a subtotal hysterectomy with bilateral salpingo-oophorectomy and a biopsy of the recto-colonic hinge. Histologic examination revealed a diagnosis of rectal endometriosis. The purpose of this work is to report a rare case of colonic endometriosis responsible for an acute large bowel obstruction.

Endoscopic mucosal resection with double band ligation versus endoscopic submucosal dissection for small rectal neuroendocrine tumors

BACKGROUND Endoscopic resection remains an effective method for the treatment of small rectal neuroendocrine tumors(NETs)(≤10 mm).Moreover,endoscopic mucosal resection(EMR)with double band ligation(EMR-dB),a simplified modification of EMR with band ligation,is an alternative strategy to remove small rectal NETs.AIM To evaluate the feasibility and safety of EMR-dB for the treatment of small rectal NETs(≤10 mm).METHODS A total of 50 patients with small rectal NETs,without regional lymph node enlargement or distant metastasis confirmed by endoscopic ultrasound,computerized tomography scan,or magnetic resonance imaging,were enrolled in the study from March 2021 to June 2022.These patients were randomly assigned into the EMR-dB(n=25)group or endoscopic submucosal dissection(ESD)group(n=25).The characteristics of the patients and tumors,procedure time,devices cost,complete resection rate,complications,and recurrence outcomes were analyzed.RESULTS There were 25 patients(13 males,12 females;age range 28-68 years old)in the EMR-dB group,and the ESD group contained 25 patients(15 males,10 females;age range 25-70 years old).Both groups had similar lesion sizes(EMR-dB 4.53±1.02 mm,ESD 5.140±1.74 mm;P=0.141)and resected lesion sizes(1.32±0.52 cm vs 1.58±0.84 cm;P=0.269).Furthermore,the histological complete resection and en bloc resection rates were achieved in all patients(100%for each).In addition,there was no significant difference in the complication rate between the two groups.However,the procedure time was significantly shorter and the devices cost was significantly lower in the EMRdB group.Besides,there was no recurrence in both groups during the follow-up period.CONCLUSION The procedure time of EMR-dB was shorter compared with ESD,and both approaches showed a similar curative effect.Taken together,EMR-dB was a feasible and safe option for the treatment of small rectal NETs.

Comparative analysis of the short and medium-term efficacy of the Da Vinci robot versus laparoscopic total mesangectomy for rectal cancer

BACKGROUND The Da Vinci robot-assisted surgery technique has been widely used in laparo-scopic mesangectomy for rectal cancer.However,the short-term efficacy of these procedures compared to traditional laparoscopic surgery remains controversial.The purpose of this study was to compare and analyze the short-and medium-term efficacy of Da Vinci robot and laparoscopic surgery in total mesangectomy(TME)for rectal cancer,so as to provide guidance and reference for clinical practice.AIM To investigate the safety and long-term efficacy of robotic and laparoscopic total mesorectal resection for the treatment of rectal cancer.METHODS The clinicopathologic data of 240 patients who underwent TME for rectal cancer in the Anorectal Department of People’s Hospital of Xinjiang Uygur Autonomous Region from August 2018 to March 2023 were retrospectively analyzed.Among them,112 patients underwent laparoscopic TME(L-TME)group,and 128 patients underwent robotic TME(R-TME)group.The intraoperative,postoperative,and follow-up conditions of the two groups were compared.RESULTS The conversion rate of the L-TME group was greater than that of the R-TME group(5.4%vs 0.8%,χ^(2)=4.417,P=0.036).The complication rate of the L-TME group was greater than that of the R-TME group(32.1%vs 17.2%,χ^(2)=7.290,P=0.007).The percentage of positive annular margins in the L-TME group was greater than that in the R-TME group(7.1%vs 1.6%,χ^(2)=4.658,P=0.031).The 3-year disease-free survival(DFS)rate and overall survival(OS)rate of the L-TME group were lower than those of the R-TME group(74.1%vs 85.2%,χ^(2)=4.962,P=0.026;81.3%vs 91.4%,χ^(2)=5.494,P=0.019);in patients with American Joint Committee on Cancer stage Ⅲ DFS rate and OS rate in the L-TME group were significantly lower than those in the R-TME group(52.5%vs 76.1%,χ^(2)=5.799,P=0.016;65.0%vs 84.8%,χ^(2)=4.787,P=0.029).CONCLUSION Compared with the L-TME group,the R-TME group had a better tumor prognosis and was more favorable for patients with rectal cancer,especially for patients with stage Ⅲ rectal cancer.

Prediction of pathological complete response and prognosis in locally advanced rectal cancer

BACKGROUND Colorectal cancer is currently the third most common malignant tumor and the second leading cause of cancer-related death worldwide.Neoadjuvant chemoradiotherapy(nCRT)is standard for locally advanced rectal cancer(LARC).Except for pathological examination after resection,it is not known exactly whether LARC patients have achieved pathological complete response(pCR)before surgery.To date,there are no clear clinical indicators that can predict the efficacy of nCRT and patient outcomes.AIM To investigate the indicators that can predict pCR and long-term outcomes following nCRT in patients with LARC.METHODS Clinical data of 128 LARC patients admitted to our hospital between September 2013 and November 2022 were retrospectively analyzed.Patients were categorized into pCR and non-pCR groups.Univariate analysis(using the χ^(2) test or Fisher’s exact test)and logistic multivariate regression analysis were used to study clinical predictors affecting pCR.The 5-year disease-free survival(DFS)and overall survival(OS)rates were calculated using Kaplan-Meier analysis,and differences in survival curves were assessed with the log-rank test.RESULTS Univariate analysis showed that pretreatment carcinoembryonic antigen(CEA)level,lymphocyte-monocyte ratio(LMR),time interval between neoadjuvant therapy completion and total mesorectal excision,and tumor size were correlated with pCR.Multivariate results showed that CEA≤5 ng/mL(P=0.039),LMR>2.73(P=0.023),and time interval>10 wk(P=0.039)were independent predictors for pCR.Survival analysis demonstrated that patients in the pCR group had significantly higher 5-year DFS rates(94.7%vs 59.7%,P=0.002)and 5-year OS rates(95.8%vs 80.1%,P=0.019)compared to the non-pCR group.Tumor deposits(TDs)were significantly correlated with shorter DFS(P=0.002)and OS(P<0.001).CONCLUSION Pretreatment CEA,LMR,and time interval contribute to predicting nCRT efficacy in LARC patients.Achieving pCR demonstrates longer DFS and OS.TDs correlate with poor prognosis.

Prognostic value of preoperative carcinoembryonic antigen/tumor size in rectal cancer

BACKGROUND Carcinoembryonic antigen(CEA)is a commonly used biomarker in colorectal cancer.However,controversy exists regarding the insufficient prognostic value of preoperative serum CEA alone in rectal cancer.Here,we combined preoperative serum CEA and the maximum tumor diameter to correct the CEA level,which may better reflect the malignancy of rectal cancer.AIM To assess the prognostic impact of preoperative CEA/tumor size in rectal cancer.METHODS We retrospectively reviewed 696 stage I to III rectal cancer patients who underwent curative tumor resection from 2007 to 2012.These patients were randomly divided into two cohorts for cross-validation:training cohort and validation cohort.The training cohort was used to generate an optimal cutoff point and the validation cohort was used to further validate the model.Maximally selected rank statistics were used to identify the optimum cutoff for CEA/tumor size.The Kaplan-Meier method and log-rank test were used to plot the survival curve and to compare the survival data.Univariate and multivariate Cox regression analyses were used to determine the prognostic value of CEA/tumor size.The primary and secondary outcomes were overall survival(OS)and disease-free survival(DFS),respectively.RESULTS In all,556 patients who satisfied both the inclusion and exclusion criteria were included and randomly divided into the training cohort(2/3 of 556,n=371)and the validation cohort(1/3 of 556,n=185).The cutoff was 2.429 ng/mL per cm.Comparison of the baseline data showed that high CEA/tumor size was correlated with older age,high TNM stage,the presence of perineural invasion,high CEA,and high carbohydrate antigen 19-9(CA 19-9).Kaplan-Meier curves showed a manifest reduction in 5-year OS(training cohort:56.7%vs 81.1%,P<0.001;validation cohort:58.8%vs 85.6%,P<0.001)and DFS(training cohort:52.5%vs 71.9%,P=0.02;validation cohort:50.3%vs 79.3%,P=0.002)in the high CEA/tumor size group compared with the low CEA/tumor size group.Univariate and multivariate analyses identified CEA/tumor size as an independent prognostic factor for OS(training cohort:hazard ratio(HR)=2.18,95%confidence interval(CI):1.28-3.73,P=0.004;validation cohort:HR=4.83,95%CI:2.21-10.52,P<0.001)as well as DFS(training cohort:HR=1.47,95%CI:0.93-2.33,P=0.096;validation cohort:HR=2.61,95%CI:1.38-4.95,P=0.003).CONCLUSION Preoperative CEA/tumor size is an independent prognostic factor for patients with stage I-III rectal cancer.Higher CEA/tumor size is associated with worse OS and DFS.

Is endoscopic ultrasonography essential for endoscopic resection of small rectal neuroendocrine tumors?

AIM To evaluate the importance of endoscopic ultrasonography(EUS) for small(≤ 10 mm) rectal neuroendocrine tumor(NET) treatment.METHODS Patients in whom rectal NETs were diagnosed by endoscopic resection(ER) at the Pusan National University Yangsan Hospital between 2008 and 2014 were included in this study. A total of 120 small rectal NETs in 118 patients were included in this study. Histologic features and clinical outcomes were analyzed, and the findings of endoscopy, EUS and histology were compared. RESULTS The size measured by endoscopy was not significantly different from that measured by EUS and histology(r = 0.914 and r = 0.727 respectively). Accuracy for the depth of invasion was 92.5% with EUS. No patients showed invasion of the muscularis propria or metastasis to the regional lymph nodes. All rectal NETswere classified as grade 1 and demonstrated an L-cell phenotype. Mean follow-up duration was 407.54 ± 374.16 d. No patients had local or distant metastasis during the follow-up periods. CONCLUSION EUS is not essential for ER in the patient with small rectal NETs because of the prominent morphology and benign behavior.

Transrectal ultrasound and magnetic resonance imaging measurement of extramural tumor spread in rectal cancer

AIM： To evaluate the agreement between transrectal ultrasound （TRUS） and magnetic resonance imaging （MRI） in classification of ≥ T3 rectal tumors. METHODS： From January 2010 to January 2012, 86 consecutive patients with ≥ T3 tumors were included in this study. The mean age of the patients was 66.4 years （range： 26-91 years）. The tumors were all ≥ T3 on TRUS. The sub-classification was defined by the penetration of the rectal wall： a： 0 to 1 mm; b： 1-5 mm, c： 6-15; d： 〉 15 mm. Early tumors as ab （≤ 5 ram） and advanced tumors as cd （〉 5 mm）. All patients underwent TRUS using a 6.5 MHz transrectal transducer. The MRI was performed with a 1.5 T Phil- ips unit. The TRUS findings were blinded to the radiol- ogist performing the interpretation of the MRI images and measuring the depth of extramural tumor spread RESULTS： TRUS found 51 patients to have an early ≥ T3 tumors and 35 to have an advanced tumor, where- as MRI categorized 48 as early ≥ T3 tumors and 38 as advanced tumors. No patients with tumors classified as advanced by TRUS were found to be early on MRI. The kappa value in classifying early versus advanced T3 rectal tumors was 0.93 （95% CI： 0.85-1.00）. We found a kappa value of 0.74 （95% CI： 0.63-0.86） for the total sub-classification between the two methods. The mean maximal tumor outgrowth measured by TRUS, 5.5 mm ± 5.63 mm and on MRI, 6.3 mm ±6.18 mm, P = 0.004. In 19 of the 86 patients the following CT scan or surgery revealed distant metastases; of the 51 patients in the ultrasound ab group three （5.9%） had metastases, whereas 16 （45.7%） of 35 in the cd group harbored distant metastases, P = 0.00002. The odds ratio of having distant metastases in the ultra- sound cd group compared to the ab group was 13.5 （95% CI： 3.5-51.6）, P = 0.00002. The mean maximal ultrasound measured outgrowth was 4.3 mm （95% CI： 3.2-5.5 mm） in patients without distant metastases, while the mean maximal outgrowth was 9.5 mm （95% CI： 6.2-12.8 ram） in the patients with metastases, P = 0.00004. Using the MRI classification three （6.3%） of 48 in the MRI ab group had distant metastases, while 16 （42.1%） of the 38 in the MRI cd group, P = 0.00004. The MRI odds ratio was 10.9 （95% CI： 2.9-41.4）, P = 0.00008. The mean maximal MRI measured out- growth was 4.9 mm （95% CI： 3.7-6.1 turn） in patients without distant metastases, while the mean maximal outgrowth was 11.5 mm （95% CI： 7.8-15.2 mm） in the patients with metastases, P = 0.000006. CONCLUSION： There is good agreement between TRUS and MRI in the pretreatment sub-classification of ≥ T3 tumors. Distant metastases are more frequent in the advanced group.

Characteristics and long-term prognosis of patients with rectal neuroendocrine tumors

AIM: To analyze the clinicopathologic characteristics and prognostic factors of rectal neuroendocrine tumors.

Clinical impact of atypical endoscopic features in rectal neuroendocrine tumors

AIM: To validate the association between atypical endoscopic features and lymph node metastasis(LNM).METHODS: A total of 247 patients with rectal neuroendocrine tumors(NETs) were analyzed. Endoscopic images were reviewed independently by two endoscopists, each of whom classified tumors by sized and endoscopic features, such as shape, color, and surface change(kappa coefficient 0.76 for inter-observer agreement). All of patients underwent computed tomography scans of abdomen and pelvis for evaluation of LNM. Univariate and multivariate analyses were performed to identify the factors associated with LNM. Additionally, the association between endoscopic atypical features and immunohistochemical staining of tumors was analyzed.RESULTS: Of 247 patients, 156(63.2%) were male and 15(6.1%) were showed positive for LNM. On univariate analysis, tumor size(P < 0.001), shape(P < 0.001), color(P < 0.001) and surface changes(P < 0.001) were significantly associated with LNM. On multivariate analysis, tumor size(OR = 11.53, 95%CI: 2.51-52.93, P = 0.002) and atypical surface(OR = 27.44, 95%CI: 5.96-126.34, P < 0.001) changes were independent risk factors for LNM. The likelihood of atypical endoscopic features increased as tumor size increased. Atypical endoscopic features were associated with LNM in rectal NETs < 10 mm(P = 0.005) and 10-19 mm(P = 0.041) in diameter. Immunohistochemical staining showed that the rate of atypical endoscopic features was higher in non L-cell tumors.CONCLUSION: Atypical endoscopic features as well as tumor size are predictive factors of LNM in patients with rectal NETs.

Neurofibromatosis type 1-associated multiple rectal neuroendocrine tumors: A case report and review of the literature

Neurofibromatosis type 1(NF-1) is commonly associated with benign or malignant tumors in both the central and peripheral nervous systems. However, rare cases of NF-1-associated multiplerectal neuroendocrine tumors have been reported. This report describes a case of a 39 year old female with NF-1 and intermittent hematochezia as a primary symptom. Physical examination showed multiple subcutaneous nodules and café au lait spots with obvious scoliosis of the back. Imaging examinations and colonoscopy found malformation of the left external iliac vein and multiple gray-yellow nodules with varying sizes and shapes in the rectal submucosal layer. Histological and immunohistochemical results suggested multiple rectal neuroendocrine tumors, a rare disease with few appreciable symptoms and a particularly poor prognosis. The patient with NF-1 presented here had not only multiple rectal neuroendocrine neoplasms but also vascular malformations, scoliosis and other multiple system lesions. This case therefore contributes to improving clinical understanding, diagnosis and treatment of related complications for patients with NF-1 who present with associated medical conditions.

Rectal neuroendocrine tumors:Current advances in management,treatment,and surveillance

Rectal neuroendocrine neoplasms(r-NENs)are considered among the most frequent digestive NENs,together with small bowel NENs.Their incidence has increased over the past few years,and this is probably due to the widespread use of endoscopic screening for colorectal cancer and the advanced endoscopic procedures available nowadays.According to the current European Neuroendocrine Tumor Society(ENETS)guidelines,well-differentiated r-NENs smaller than 10 mm should be endoscopically removed in view of their low risk of local and distant invasion.R-NENs larger than 20 mm are candidates for surgical resection because of their high risk of distant spreading and the involvement of the muscularis propria.There is an area of uncertainty regarding tumors between 10 and 20 mm,in which the metastatic risk is intermediate and the endoscopic treatment can be challenging.Once removed,the indications for surveillance are scarce and poorly codified by international guidelines,therefore in this paper,a possible algorithm is proposed.

Predicting tumor response after preoperative chemoradiation using clinical parameters in rectal cancer

AIM: To evaluate the clinical parameters and identify a better method of predicting pathological complete response (pCR). METHODS: We enrolled 249 patients from a database of 544 consecutive rectal cancer patients who underwent surgical resection after preoperative chemoradiation therapy (PCRT). A retrospective review of morphological characteristics was then performed to collect data regarding rectal examination findings. A scoring model to predict pCR was then created. To validate the ability of the scoring model to predict complete regression.RESULTS: Seventy patients (12.9%) achieved a pCR. A multivariate analysis found that pre-CRT movability (P = 0.024), post-CRT size (P = 0.018), post-CRT morphology (P = 0.023), and gross change (P = 0.009) were independent predictors of pCR. The accuracy of the scoring model was 76.8% for predicting pCR with the threshold set at 4.5. In the validation set, the accuracy was 86.7%. CONCLUSION: Gross changes and morphological findings are important predictors of pathological response. Accordingly, PCRT response is best predicted by a combination of clinical, laboratory and metabolic information.

Colorectal cancer screening by non-invasive metabolic biomarker fecal tumor M2-PK

AIM: To evaluate the utility of the innovative fecal tumor M2-Pyruvate kinase (M2-PK) test in our daily clinical routine, as a marker for the pre-selection of patients who should subsequently undergo colonoscopy for the diagnosis or exclusion of colorectal cancer. METHODS: Fecal tumor M2-PK was measured in stool samples of 96 study participants (33 patients with colorectal cancer, 21 patients with rectal carcinoma and 42 controls) who all underwent total colonoscopy. RESULTS: In 39 of 42 individuals in the control group, fecal tumor M2-PK was below 4.0 kU/L (93% specificity). Colorectal tumors were accompanied by a highly significant increase (P < 0.001) in fecal tumor M2- PK levels (median: colon carcinoma, 23.1 kU/L; rectal carcinoma, 6.9 kU/L; colorectal carcinoma, 14.7 kU/L), which correlated with Duke’s staging and T-classification. The overall sensitivity was 78% for colorectal cancer, increasing from 60% for stage T1 to 100% for stage T4 and from 60% for Duke’s A to 90% for Duke’s D tumors. CONCLUSION: Fecal tumor M2-PK is an appropriately sensitive tool to pre-select those patients requiring colonoscopy for the further diagnostic confirmation or exclusion of colorectal cancer.

Rectal neuroendocrine tumor with uncommon metastatic spread:A case report and review of literature

Neuroendocrine tumors of the gastrointestinal tract are rare neoplasms. Rectal neuroendocrine tumors consist approximately the 5%-14% of all neuroendocrine neoplasms in Europe. These tumors are diagnosed in relatively young patients,with a mean age at diagnosis of 56 years. Distant metastases from rectal neuroendocrine tumors are not very common. Herein we describe a case of a rectal neuroendocrine tumor which metastasized to the lung,mediastinum and orbit. This case underscores the importance of early identification and optimal management to improve patient's prognosis. Therefore,the clinical significance of this case is the necessity of physicians' awareness and education regarding neuroendocrine tumors' diagnosis and management.

Morphological observation of tumor infiltrating immunocytes in human rectal cancer

AIM： To investigate the morphological characterization of tumor infiltrating dendritic cells （TIDCs） and tumor infiltrating lymphocytes （TILs） in human rectal cancer. METHODS： Light and electron microscopy as well as immunohistochemistry were used to observe the distributive and morphological changes of TIDCs and TILs. RESULTS： TIDCs were mainly located in tumor-surrounding tissue. The number of TIDCs in the earlier stage was higher than that in the later stage （P〈 0.01）. TILs were mainly seen in adjacent tissue of cancers and tumor-surrounding tissue. There were more TILs in the earlier stage than that in the later stage （P〈0.01）. Under electron microscope, TIDCs were irregular in shape and exhibited many dendritic protrusions. It isn＇t obvious that cancer cells perforated the basement membrane and TILs were arranged along the basement membrane in the earlier stage. In the later stage, it is explicit that cancer cells perforated the basement membrane and surrounded by TILs. There were contacts among TIDCs, TILs and tumor cell. One IIDCs contacted one or several TILs which clustered around TIDCs. Glycogen granules were seen between TIDCs and Tits. CONCLUSION： The number of TIDCs and TILs is related with tumor progression There exist close relationships among TIDCs, TILs and tumor cell.

Radiomics for differentiating tumor deposits from lymph node metastasis in rectal cancer

BACKGROUND Tumor deposits(TDs)are not equivalent to lymph node(LN)metastasis(LNM)but have become independent adverse prognostic factors in patients with rectal cancer(RC).Although preoperatively differentiating TDs and LNMs is helpful in designing individualized treatment strategies and achieving improved prognoses,it is a challenging task.AIM To establish a computed tomography(CT)-based radiomics model for preoperatively differentiating TDs from LNM in patients with RC.METHODS This study retrospectively enrolled 219 patients with RC[TDs+LNM-(n=89);LNM+TDs-(n=115);TDs+LNM+(n=15)]from a single center between September 2016 and September 2021.Single-positive patients(i.e.,TDs+LNM-and LNM+TDs-)were classified into the training(n=163)and validation(n=41)sets.We extracted numerous features from the enhanced CT(region 1:The main tumor;region 2:The largest peritumoral nodule).After deleting redundant features,three feature selection methods and three machine learning methods were used to select the best-performing classifier as the radiomics model(Rad-score).After validating Rad-score,its performance was further evaluated in the field of diagnosing double-positive patients(i.e.,TDs+LNM+)by outlining all peritumoral nodules with diameter(short-axis)>3 mm.RESULTS Rad-score 1(radiomics signature of the main tumor)had an area under the curve(AUC)of 0.768 on the training dataset and 0.700 on the validation dataset.Rad-score 2(radiomics signature of the largest peritumoral nodule)had a higher AUC(training set:0.940;validation set:0.918)than Radscore 1.Clinical factors,including age,gender,location of RC,tumor markers,and radiological features of the largest peritumoral nodule,were excluded by logistic regression.Thus,the combined model was comprised of Rad-scores of 1 and 2.Considering that the combined model had similar AUCs with Rad-score 2(P=0.134 in the training set and 0.594 in the validation set),Rad-score 2 was used as the final model.For the diagnosis of double-positive patients in the mixed group[TDs+LNM+(n=15);single-positive(n=15)],Rad-score 2 demonstrated moderate performance(sensitivity,73.3%;specificity,66.6%;and accuracy,70.0%).CONCLUSION Radiomics analysis based on the largest peritumoral nodule can be helpful in preoperatively differentiating between TDs and LNM.

Laterally spreading tumor-like primary rectal mucosa-associated lymphoid tissue lymphoma:A case report

BACKGROUND Colorectal mucosa-associated lymphoid tissue(MALT)lymphoma is a rare disease,and only a few cases have been reported to date.It has no specific clinical presentations and shows various endoscopic appearances.There is no uniform consensus on its treatment.With the advancement of endoscopic technology,endoscopic treatment has achieved better results in individual case reports of early-stage patients.CASE SUMMARY We report a case of rectal MALT in a 57-year-old Chinese man with no symptoms who received endoscopy as part of a routine physical examination,which incidentally found a 25 mm×20 mm,laterally spreading tumor(LST)-like elevated lesion in the rectum.Therefore,he was referred to our hospital for further endoscopic treatment.Complete and curable removal of the tumor was performed by endoscopic submucosal dissection.We observed enlarged and dilated branch-like vessels similar to those of gastric MALT lymphoma on magnifying endoscopy with narrow-band imaging.And immunopathological staining showed hyperplastic capillaries in the mucosa.Histopathological findings revealed diffusely hyperplastic lymphoid tissue in the lamina propria,with a visible lymphoid follicle structure surrounded by a large number of diffusely infiltrated lymphoid cells that had a relatively simple morphology and clear cytoplasm.In addition,immunohistochemical analysis suggested strongly positive expression for CD20 and Bcl-2.Gene rearrangement results showed positivity for IGH-A,IGH-C,IGK-B,and IGL.Taking all the above findings together,we arrived at a diagnosis of extranodal marginal zone B-cell lymphoma of MALT lymphoma. Positron emission tomography-computed tomographyexamination showed no other lesions involved. The patient will be followed byperiodic endoscopic observation.CONCLUSIONIn conclusion, we report a case of rectal MALT with an LST-like appearancetreated by endoscopic submucosal dissection. Further studies will be needed toexplore the clinical behavior, endoscopic appearance, and treatment of rectalMALT.