Vascular endothelial growth factor-A is an Immunohistochemical biomarker for the efficacy of bevacizumab-containing chemotherapy for duodenal and jejunal adenocarcinoma.

BACKGROUND: The efficacy and safety of bevacizumab-containing chemotherapy for patients with metastatic duodenal and jejunal adenocarcinoma (mDJA) are unclear. The present study aimed to evaluate the efficacy of bevacizumab and to explore immunohistochemical markers that can predict the efficacy of bevacizumab for patients with mDJA. METHODS: This multicentre study included patients with histologically confirmed small bowel adenocarcinoma who received palliative chemotherapy from 2008 to 2017 at 15 hospitals. Immunostaining was performed for vascular endothelial growth factor-A (VEGF-A), TP53, Ki67, ß-catenin, CD10, MUC2, MUC5AC, MUC6, and mismatch repair proteins. RESULTS: A total of 74 patients were enrolled, including 65 patients with mDJA and 9 with metastatic ileal adenocarcinoma. Patients with mDJA who received platinum-based chemotherapy with bevacizumab as first-line treatment tended to have a longer progression-free survival and overall survival than those treated without bevacizumab (P = 0.075 and 0.077, respectively). Multivariate analysis extracted high VEGF-A expression as a factor prolonging progression-free survival (hazard ratio: 0.52, 95% confidence interval: 0.30-0.91). In mDJA patients with high VEGF-A expression, those who received platinum-based chemotherapy with bevacizumab as a first-line treatment had significantly longer progression-free survival and tended to have longer overall survival than those treated without bevacizumab (P = 0.025 and P = 0.056, respectively), whereas no differences were observed in mDJA patients with low VEGF-A expression. CONCLUSION: Immunohistochemical expression of VEGF-A is a potentially useful biomarker for predicting the efficacy of bevacizumab-containing chemotherapy for patients with mDJA.

How to Manage Small Intestine (Jejunal and Ileal) Neuroendocrine Neoplasms Presenting with Liver Metastases?

PURPOSE OF REVIEW: Small intestinal neuroendocrine neoplasms (siNENs) are slowly growing tumours with a low malignant potential. However, more than half of the patients present with distant metastases (stage IV) and nearly all with locoregional lymph node (LN) metastases at the time of surgery. The value of locoregional treatment is discussed controversially. RECENT FINDINGS: In stage I to III disease, locoregional surgery was currently shown to be curative prolonging survival. In stage IV disease, surgery may prolong survival in selected patients with the chance to cure locoregional disease besides radical/debulking liver surgery. It may improve the quality of life and may prevent severe local complications resulting in a state of chronic malnutrition and severe intestinal ischaemia or bowel obstruction. Locoregional tumour resection offers the opportunity to be curative or to focus therapeutically on liver metastasis, facilitating various other therapeutic modalities. Risks and benefits of the surgical intervention need to be balanced individually.

Small Bowel Adenocarcinomas: Impact of Location on Survival.

BACKGROUND: Proximal (duodenal) small bowel adenocarcinomas have a worse prognosis than distal (jejuno-ileal) tumors, but differences in patient, tumor, and treatment factors between locations remain unclear. METHODS: Patients in the National Cancer Database with surgically resected pathologic stage I-IV small bowel adenocarcinomas between 2004 and 2015 were analyzed. Clinical stage IV patients were excluded. RESULTS: Proximal tumors (n = 3767) were more likely to be higher grade (OR 1.52, CI 1.22-1.85 for moderately; OR 1.83, CI 1.49-2.33 for poorly differentiated, P < 0.01 for both) and have positive lymph nodes (OR 2.04, CI 1.30-3.23, P < 0.01), while distal tumors (n = 3252) were likely to be larger (OR 1.31, CI 1.07-1.60 for size > 5 cm, P < 0.01). Proximal tumors were associated with worse overall survival (OS) and stage-specific survival compared with distal tumors (all P < 0.01). Cox regression analysis of the entire cohort showed worse survival with community versus academic cancer programs, higher comorbidity scores, pathologic stage IV, poorly differentiated histology, positive nodal or margin status, and proximal location, while female gender, larger tumor size, and chemotherapy predicted better survival. On separate Cox regression analyses of each location, neoadjuvant chemotherapy was associated with better OS in the proximal cohort (HR 0.70, CI 0.55-0.88, P < 0.01), while adjuvant chemotherapy was associated with better OS for both proximal (HR 0.49, CI 0.42-0.57, P < 0.01) and distal tumors (HR 0.68, CI 0.57-0.81, P < 0.01). CONCLUSIONS: Proximal small bowel adenocarcinomas are associated with worse overall and stage-specific survival. This may be due to tumor biologic differences as proximal tumors were more likely to have higher grade. Future studies should further investigate differences between proximal and distal tumors to guide targeted treatment algorithms.

Prognostic relevance of programmed death-ligand 1 expression and microsatellite status in small bowel adenocarcinoma.

Background: Small bowel adenocarcinoma (SBA) is a dreadful disease. Patient prognosis is limited due to late presentation and ineffective chemotherapy. PD-1/PD-L1 checkpoint immunotherapy is regarded as a promising approach in several cancer entities. The association of PD-1/PD-L1 expression and its impact on patient prognosis with SBA is unclear. Material and methods: Seventy-five consecutive patients who underwent surgery for SBA were retrospectively analyzed and stained for PD-L1 expression in the tumour or the stroma. Analysis of mismatch repair genes was performed to determine microsatellite status. Kaplan-Meier estimate was used to analyze patient survival. Univariate and multivariable Cox regression-analyses were used to assess the impact of PD-L1 expression and microsatellite status on patient survival.Results: PD-L1 was weakly upregulated within the tumour or the stroma and associated with prolonged survival (p = .0071 and p = .0472, respectively). Fifty-one tumours (68%) revealed microsatellite stability (MSS) and 24 tumours (32%) were microsatellite instable (MSI) without correlating with patient survival (p = .611). Neither PD-L1 expression in the tumour nor in the stroma was identified as an independent risk factor influencing survival (p = .572 and p = .3055).Conclusion: Although PD-L1 expression is associated with prolonged survival, it was not identified as an independent prognostic marker. Microsatellite status did not influence long-term survival.

Misdiagnosis of multiple synchronous small bowel adenocarcinomas as intestinal tuberculosis: a case report.

BACKGROUND: Small bowel adenocarcinoma (SBA) is a rare malignancy that primarily occurs in the duodenum. Multiple synchronous SBA is unique rare and difficult to diagnose due to non-specific disease presentation. Protocols to identify multiple synchronous SBA during early disease stages are urgently required. CASE PRESENTATION: An elderly man experienced left lower abdominal pain and melena for 3 months. Abdominal CT showed thickening of the multiple segmental small intestinal walls. As the patient had pulmonary tuberculosis simultaneously, he was misdiagnosis as intestinal tuberculosis and received anti-spasm therapy. The treatment delayed radical resection surgery and the patient underwent palliative segmental resection of the jejunum after 4 months due to intestinal obstruction. Resected specimens showed multiple synchronous SBA (five tumors). The patient accepted chemotherapy postoperatively. Six months postoperatively, the patient died of brain metastasis. CONCLUSIONS: We highlight how multiple synchronous SBA is rare and easily misdiagnosed. We should rule out multiple synchronous SBA when diagnosing intestinal diseases (e.g. inflammatory bowel disease, IBS). Intestinal tuberculosis may also be one of the risk factors for multiple synchronous SBA. High-risk patients should be assessed for known tumor makers, and receive gastroscopy, enteroscopy or capsule endoscopy. Doctors should obtain the pathology under endoscopy to the greatest possible degree. For suspected patients, laparotomy should be performed.

[Inflammatory fibroid polyp in the jejunum - a case report].

Inflammatory fibroid polyps (IFP) are rare type of benign tumours found in the gastrointestinal tract. IFP´s are in most cases small in size and without symptoms but can cause intussuception and haemorrhage. We present a case of a 25 year old female who presented with abdominal pain and symptoms and signs of anemia, hemoglobin was 36 g/L upon arrival. Further workup revealed a large tumor in the small intestine. The patient underwent a partial resection of the proximal jejunum. Pathology of the specimen showed inflammatory fibroid polyp.

Multicenter retrospective analysis of the clinicopathologic features of monomorphic epitheliotropic intestinal T-cell lymphoma.

Monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) is a provisional entity in the 2017 World Health Organization classifications. To further elucidate the clinicopathologic features of this new disease, we carried out a retrospective, multicenter analysis of 42 patients with MEITL. The median age of the patients was 59 years (range, 20-84 years), and 27 patients (64 %) were male. Thirty-two patients (76 %) were Ann-Arbor stages I-II and 28 (67 %) were Lugano stages I-II1&2. The most frequent site of involvement was the jejunum (N = 21). Most cases expressed CD8 (79 %) and CD56 (95 %) and did not express CD30 (5 %) or EBER (0 %). The median progression-free survival was 6.9 months (95 % CI 4.3-9.6); the median OS was 14.8 months (2.4-27.2). Thirty-two patients (76 %) underwent surgery and 37 (88 %) received chemotherapy. A complete response (CR) rate was 38 %. Sixteen patients had undergone autologous stem cell transplantation (ASCT). Relapse or progression was documented in 24 cases, most frequently in the primary site (N = 23). Four cases showed central nervous system relapse. Age over 55 years, poor performance scale, advanced Lugano stage (IIE-IV), not achieving CR, and not receiving ASCT were associated with inferior OS. While the optimal management of MEITL remains undetermined, achieving CR and consolidative ASCT seem essential. As CHOP might be insufficient for achieving CR, more efficient combinations should be investigated. Additionally, considering the frequent local failure and CNS relapse, novel therapeutic approaches are required to improve survival.

Clinicopathological Features and Prognosis of Gastrointestinal Stromal Tumor Located in the Jejunum and Ileum.

BACKGROUND: Data about the clinicopathological features and prognosis of gastrointestinal stromal tumors (GISTs) located in jejunum and ileum are lacking. The present study aims to investigate the features and prognosis of jejunal and ileal GISTs based on the Surveillance, Epidemiology, and End Results (SEER) database. PATIENTS AND METHODS: Cases of jejunal and ileal GISTs were extracted from SEER database. Clinicopathological characteristics and survival data of patients were recorded. The clinicopathological features and prognosis of patients were analyzed. RESULTS: There were 399 male (56.8%) and 303 female (43.2%). The median age was 60 years (17-96). Four hundred and seventy-two tumors were located in the jejunum (67.2%) and 230 tumors in the ileum (32.8%). The median tumor size was 7.0 cm (0.5-90). The 5-, 10-, and 20-year disease specific survival (DSS) was 84.4, 71.2, and 54.2% respectively. Clinicopathological features were comparable between tumors located in the jejunum and ileum (all p > 0.05) except gender and tumor size (both p < 0.05). Jejunal GISTs, rather than ileal GISTs (p = 0.043), were commonly found in the males. The tumor size of jejunal GISTs was smaller than that of ileal GISTs (p = 0.010). The DSS of jejunal GISTs was comparable to that of ileal GISTs (p = 0.269). CONCLUSIONS: Jejunal GISTs were more common than ileal GISTs. The prognosis was comparable between jejunal and ileal GISTs.

Cystic lymphangioma in the peripheral jejunal mesentery in an adult and excision with laparoscopic-assisted surgery: a case report.

BACKGROUND: Lymphangiomas are uncommon congenital malformations that present mainly in the head, neck, and axillar regions in pediatric patients. Mesenteric cystic lymphangiomas (MCLs), which occasionally present with substantial growth and the invasion of adjacent vital structures, are rarely reported in adults. We report a case of MCL in an adult who was treated with laparoscopic-assisted excision. CASE PRESENTATION: A 40-year-old Japanese man visited his family physician for prolonged periumbilical pain. Plain computed tomography (CT) showed a low-density mass in his left abdomen, and he was referred to our hospital 2 weeks later. His abdomen was flat and soft, and no mass was felt upon palpation. Routine laboratory data showed no abnormalities in the blood cell counts. The levels of tumor markers, such as carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9), and cancer antigen 125 (CA125), were within normal ranges. Contrast-enhanced CT was performed, and a low-density mass was observed with an irregular outline and poor contrast, as well as involvement of the peripheral mesenteric artery and partial compression of the adjacent jejunum without dilatation of the oral side of the bowel. The patient was diagnosed with lymphatic cysts and observed for 1 month without symptom exacerbation. Follow-up CT showed no increase in the size of the mass but showed apparent invasion of the jejunal wall without bowel obstruction. Magnetic resonance imaging (MRI) showed intermediate intensity on T1-weighted imaging (T1WI) and high intensity on T2-weighted imaging (T2WI). The coronal view on T2WI clearly showed an accumulation of cystic lesions. We performed tumor excision with partial resection of the jejunum in a laparoscopic-assisted manner. Pathological examination showed multicystic lesions with an attenuated endothelial lining, surrounding rich adipose tissue and scattered smooth muscle fibers; the patient was diagnosed with MCL. Immunohistochemical assays supported this diagnosis. CONCLUSIONS: This is rare case of MCL presenting in an adult who underwent successful laparoscopic-assisted resection. Mesenteric lymphangioma (ML) should be considered in the differential diagnosis of patients with intraabdominal cysts. Radical excision is optimal, even when the patient is asymptomatic. Laparoscopic-assisted tumor resection is a suitable surgical method for treating MLs located in the peripheral mesentery.

Duodenal localization is a negative predictor of survival after small bowel adenocarcinoma resection: A population-based, propensity score-matched analysis.

BACKGROUND AND OBJECTIVES: This study assessed the influence of tumor localization of small bowel adenocarcinoma on survival after surgical resection. METHODS: Patients with resected small bowel adenocarcinoma, ACJJ stage I-III, were identified from the Surveillance, Epidemiology, and End Results database from 2004 to 2013. The impact of tumor localization on overall and cancer-specific survival was assessed using Cox proportional hazard regression models with and without risk-adjustment and propensity score methods. RESULTS: Adenocarcinoma was localized to the duodenum in 549 of 1025 patients (53.6%). There was no time trend for duodenal localization (P = 0.514). The 5-year cancer-specific survival rate was 48.2% (95%CI: 43.3-53.7%) for patients with duodenal carcinoma and 66.6% (95%CI: 61.6-72.1%) for patients with cancer located in the jejunum or ileum. Duodenal localization was associated with worse overall and cancer-specific survival in univariable (HR = 1.73; HR = 1.81, respectively; both P < 0.001), multivariable (HR = 1.52; HR = 1.65; both P < 0.001), and propensity score-adjusted analyses (HR = 1.33, P = 0.012; HR = 1.50, P = 0.002). Furthermore, young age, retrieval of more than 12 regional lymph nodes, less advanced stage, and married matrimonial status were positive, independent prognostic factors. CONCLUSIONS: Duodenal localization is an independent risk factor for poor survival after resection of adenocarcinoma.

Primary Jejunal adenocarcinoma - An unsuspected culprit.

Primary Small bowel adenocarcinoma, a rare entity and having varied clinical presentation, makes its clinical detection a diagnostic challenge. Moreover, its true prevalence in sub-continent population has not yet been established, which makes it more difficult for its detection. We present the case of a 60 year old male who came with abdominal pain and weight loss for two years as the only symptoms. A series of tests in the two year period remained inconclusive. Later Computed tomography showed a suspicious mass at the terminal ileum. On exploration, there was a grossly dilated jejunal loop due to stricture one foot from ligament of Trietz and mesenteric lymphadenopathy. En-bloc resection of jejunum with suspicious of malignancy was done and primary end to end anastomosis was made. Histopathology and follow up metastatic workup showed poorly differentiated adenocarcinoma of jejunum with T3N1M0. Small bowel malignancy should also be kept in mind, when managing patients with weight loss of unknown origin.

[A Case of Intussusception in the Jejunum Due to Small Intestinal Adenocarcinoma].

The patient was a woman in her 60's with an 11-month history ofpersistent epigastralgia and abdominal distension, without abnormal findings on upper endoscopy, abdominal ultrasonography, and abdominal computed tomography in other hospitals. She presented to our hospital with a complaint off requent vomiting; abdominal CT indicated intussusception in the jejunum due to a small intestinal tumor, and laparoscopic exploration and partial jejunectomy were performed. The histopathological diagnosis was tub1>tub2>pap, pT4(SE), pN1, pPM0, pDM0, pStage III A. She was treated with oral chemotherapy( S-1)and developed no recurrence 7 months after surgery. Laparoscopic exploration was useful to detect intussusception in the jejunum due to small intestinal adenocarcinoma.

The characteristics and outcomes of small bowel adenocarcinoma: a multicentre retrospective observational study.

BACKGROUND: Small bowel adenocarcinoma (SBA) is a rare malignancy that accounts for 1-2% of gastrointestinal tumours. We investigated the clinical characteristics, outcomes, and prognostic factors of primary SBA. METHODS: We retrospectively analysed the characteristics and clinical courses of 205 SBA patients from 11 institutions in Japan between June 2002 and August 2013. RESULTS: The primary tumour was in the duodenum and jejunum/ileum in 149 (72.7%) and 56 (27.3%) patients, respectively. Sixty-four patients (43.0%) with duodenal adenocarcinoma were asymptomatic and most cases were detected by oesophagogastroduodenoscopy (EGD), which was not specifically performed for the detection or surveillance of duodenal tumours. In contrast, 47 patients (83.9%) with jejunoileal carcinoma were symptomatic. The 3-year survival rate for stage 0/I, II, III, and IV cancers was 93.4%, 73.1%, 50.9%, and 15.1%, respectively. Multivariate analysis revealed performance status 3-4, high carcinoembryonic antigen, high lactate dehydrogenase (LDH), low albumin, symptomatic at diagnosis, and stage III/IV disease were independent factors for overall survival (OS). Ten patients (18.5%) with stage IV disease were treated with a combination of resection of primary tumour, local treatment of metastasis, and chemotherapy; this group had a median OS of 36.9 months. CONCLUSIONS: Although most SBA patients were diagnosed with symptomatic, advanced stage disease, some patients with duodenal carcinoma were detected in early stage by EGD. High LDH and symptomatic at diagnosis were identified as novel independent prognostic factors for OS. The prognosis of advanced SBA was poor, but combined modality therapy with local treatment of metastasis might prolong patient survival.

Small-bowel Surveillance in Patients With Peutz-Jeghers Syndrome: Comparing Magnetic Resonance Enteroclysis and Double Balloon Enteroscopy.

BACKGROUND AND STUDY AIMS: Small-bowel surveillance with polypectomy of polyps ≥15 mm prevents complications in patients with Peutz-Jeghers syndrome (PJS). We aimed to compare magnetic resonance enteroclysis (MRE) and double balloon enteroscopy (DBE) for diagnostic yield of these polyps and for patient preference. MATERIALS AND METHODS: PJS patients prospectively underwent MRE followed by proximal DBE within 20 weeks. Endoscopists were blinded to the MRE results. We compared number of polyps ≥15 mm detected by MRE and DBE. Patients' perceptions of both procedures were assessed using questionnaires. RESULTS: Fifteen PJS patients (67% males, median age 47 y) underwent both MRE and DBE. Polyps ≥15 mm were identified by MRE and/or DBE in 12/15 (80%) patients. There was no significant difference in the detection of polyps ≥15 mm (38 by MRE vs. 50 by DBE, P=0.37). Sensitivity for these polyps was 62% (38/61) for MRE and 82% (50/61) for DBE. Patients' perceived shame and burden did not differ significantly between MRE and DBE. Patients reported significantly more pain during preparation for MRE than for DBE (moderate vs. no pain, P=0.02), although perceived pain during the procedures was comparable (both mild, P=0.89). For future small-bowel surveillance 10/13 (77%) patients preferred DBE over MRE (P=0.09). CONCLUSIONS: Our results suggest that MRE and DBE have a comparable diagnostic yield of polyps ≥15 mm. However, DBE allows for direct intervention and was preferred over MRE by most patients in this series. Larger cohorts of PJS patients are needed to fully evaluate the diagnostic yield of DBE compared with other modalities.

Gastrointestinal Bleeding Due to Gastrointestinal Tract Malignancy: Natural History, Management, and Outcomes.

BACKGROUND: Gastrointestinal (GI) tumor bleeding can vary from occult bleeding to massive hemorrhage and can be the presenting sign of malignancy. AIMS: Our primary aims were to: (1) characterize the natural history, treatment, and outcomes in patients with GI tumor bleeding and (2) compare and contrast bleeding in upper GI (UGI)/small bowel (SB) and lower GI malignancies. METHODS: Patients with endoscopically confirmed tumor bleeding were identified through search of consecutive electronic medical records: Bleeding was determined by the presence of melena, hematochezia, hematemesis, or fecal occult blood. Comprehensive clinical and management data were abstracted. RESULTS: A total of 354 patients with GI tumors were identified: 71 had tumor bleeding (42 UGI/SB and 29 colonic). GI bleeding was the initial presenting symptom of malignancy in 55/71 (77%) of patients; 26/71 patients had widely metastatic disease at presentation. Further, 15 of 26 patients with metastatic disease presented with GI bleeding. Visible bleeding was present in 14/42 (33%) and 4/29 (14%) of UGI/SB and colonic tumors, respectively. Endoscopic hemostasis was attempted in 10 patients, and although initial control was successful in all, bleeding recurred in all of these patients. The most common endoscopic lesion was clean-based tumor ulceration. Overall mortality at 1 year was 57% for esophageal/gastric, 14% for SB, and 33% for colonic tumors. CONCLUSIONS: When patients with GI malignancy present with GI bleeding, it is often the index symptom. Initial endoscopic hemostasis is often successful, but rebleeding is typical. Esophageal and gastric tumors carry the poorest prognosis, with a high 1-year mortality rate.

Congenital intestinal fibrosarcoma with rapid recurrence requiring adjuvant chemotherapy.

A total of 16 cases of congenital fibrosarcoma have been reported from 1975 to March 2015. Five of the 16 had abnormal fusion between erythroblast transformation specific translocation variant 6 and neurotrophin recptor gene neurotrophic tyrosine kinase, receptor, type 3 (ETV6-NTRK3); in another five out of 16 this was absent, and six were not tested. All were managed by surgical resection but none involved metastasis. Herein we report the case of a newborn baby girl with congenital fibrosarcoma negative for ETV6-NTRK3 gene fusion, who presented with ileal perforation and positive resection margin. She had rapid recurrence with lymph node metastasis treated with postoperative chemotherapy. There was no further recurrence at >3 years of follow up.

Primary pancreatic-type acinar cell carcinoma of the jejunum with tumor thrombus extending into the mesenteric venous system: a case report and literature review.

BACKGROUND: Although ectopic pancreatic tissue is common in the upper gastrointestinal tract, the incidence of ectopic pancreatic tissue in the jejunum is low, and malignant transformation in ectopic pancreatic tissue is rare. Furthermore, pancreatic-type acinar cell carcinoma (ACC) developing in the jejunum and ACC accompanied by tumor thrombus are extremely rare. CASE PRESENTATION: A 78-year-old-woman presented with melena. Abdominal computed tomography images and endoscopic examination revealed a submucosal jejunal mass with tumor thrombus extending into a jejunal vein. The patient underwent a curative resection combined with a partial jejunectomy and partial pancreatectomy. Histopathological examination of the resected tissue showed tumor cells with a homogeneous acinar architecture identical to pancreatic-type ACC and tumor thrombus. Postoperatively, she was followed for 10 months and had no recurrence. CONCLUSION: We present an extremely rare case of pancreatic-type ACC in the jejunum with extensive tumor thrombus invading into the mesenteric venous system. This type of cancer has not been reported previously but should be considered in the differential diagnosis of a jejunal mass.

[A Case of Jejunal Ectopic Pancreatic Cancer with Small Bowel Obstruction].

Were port a caseof an 82-year-old man who presented with vomiting. Computed tomography(CT)revealed a jejunum tumor and small bowel obstruction. Enteroscopy revealed a protruded lesion and biopsy indicated adenocarcinoma. PET-CT revealed nothing without jejunal tumor. Therefore, with a preoperative diagnosis of primary small bowel cancer, we performed operation. Surgery indicated peritoneal disseminations and a jejunal tumor 40 cm distal from the ligament of Treitz, and we performed small bowel partial resection. Pathological examination revealed adenocarcinoma originating from a Heinrich type I ectopic pancreas in the jejunum. Ectopic pancreatic cancer in the jejunum is rare, and we review case reports in the literature.

Lymphadenectomy during Small Bowel Neuroendocrine Tumor Surgery: The Concept of Skip Metastases.

BACKGROUND: More than half of small bowel neuroendocrine tumors (SB-NETs) are metastatic at diagnosis, but complete resection of the primary tumor and lymph node (LN) is recommended by most authors. Our aim was to describe the pattern of involved LN after an extensive LN resection. MATERIALS AND METHODS: Between July 2013 and December 2015, all consecutive patients who underwent resection of at least one SB-NET in our European Neuroendocrine Tumor Society Center of Excellence were prospectively included, while patients with duodenal SB-NETs were excluded. The resection and pathological analysis of LNs were standardized using three groups (group 1, along the small intestine; group 2, along the mesenteric vessel; and group 3, retropancreatic and mesenteric vessel origin). RESULTS: Twenty-eight patients with SB-NET resection were prospectively enrolled in the study, with seven patients being excluded from the analysis because it was impossible to divide the operative piece into nodal groups due to retractile mesenteritis. Among the remaining 21 patients, 20 (95 %) had LNs involved; 8 (38 %) in group 1, 13 (62 %) in group 2, and 12 (57 %) in group 3. Skip metastases were found in 14 patients (67 %): 4 (19 %) with an invasion pattern of group 3+ without group 2+, and 12 (57 %) with an invasion pattern of group 2+ or group 3+ without group 1+. CONCLUSION: As a result of skip metastases, systematic, extensive LN resection in retropancreatic portion may be required to prevent unresectable locoregional recurrence.