The surgical anatomy of the lymphatic system of the pancreas

Mesopancreas-Anatomical Insights and Its Implications for Diagnosis and Clinical and Surgical Practice

Background: The concept of mesopancreas is frequently discussed in the surgical literature as the neural pathway for metastatic spread in pancreatic head cancer. It generally refers to a retro-pancreatic plane that should be resected to reduce the incidence of regional metastases. However, this concept remains poorly defined, both embryologically and anatomically. Our objective was to establish a clear embryological and anatomical definition of the mesopancreas, making anatomical data more applicable in surgical practice. Methods: We examined seven cadavers (5 males, 2 females, aged 62-71) with no medical or surgical history, preserved in 9% formalin at Carol Davila University's Anatomy Department. Regional dissections were performed in successive planes, highlighting the celiac ganglia and the associated network of neural connections that comprise the mesopancreas. Results: Our study defines the "mesopancreas" as remnants of primordial mesenteries that coalesced into the Treitz fascia. We identified its functional components as nerve fibers linking the celiac ganglia and superior mesenteric plexus to the pancreas, along with vascular structures, lymphatics, and connective and adipose tissue. These components likely contribute to regional metastasis in pancreatic head cancer. While resection of the mesopancreas could help prevent metastasis, its complex anatomy and proximity to major vessels pose significant surgical challenges. Conclusions: Based on our findings, we propose a plausible definition for the term "mesopancreas". It encompasses the structures that originated as part of the primordial mesenteries, which subsequently coalesced, resulting in the formation of the Treitz fascia. In essence, the mesopancreas is the functional content of a former mesentery.

A head with two tales: demystifying early spread of disease from the pancreatic head

The pancreas is a centrally located extraperitoneal organ within the anterior pararenal space. It is extensively connected to the extraperitoneal spaces by location and a network of mesenteries and ligaments. This provides interconnected avenues for vessels, lymphatics, and nerves to course through-as well as avenues for the spread of disease. The head of the pancreas results from the fusion of its ventral analog (anterior head) with its dorsal analog (posterior head). This differentiation provides two distinct pathways of spread of disease from the head of the pancreas. This communication will discuss the embryology, anatomy, and pathways of disease spread from the anterior and posterior pancreatic head. While any disease process can use these pathways, proven cases of adenocarcinoma of the pancreas are used for illustrations.

Imaging the pancreas with photon-counting CT - A review of normal pancreatic anatomy

PURPOSE

Compared to conventional energy integrating detector CT, Photon-Counting CT (PCCT) has the advantage of increased spatial resolution. The pancreas is a highly complex organ anatomically. The increased spatial resolution of PCCT challenges radiologists' knowledge of pancreatic anatomy. The purpose of this review was to review detailed macroscopic and microscopic anatomy of the pancreas in the context of current and future PCCT.

METHOD

This review is based on a literature review of all parts of pancreatic anatomy and a retrospective imaging review of PCCT scans from 20 consecutively included patients without pancreatic pathology (mean age 61.8 years, 11 female), scanned in the workup of pancreatic cancer with a contrast enhanced multiphase protocol. Two radiologists assessed the visibility of the main and accessory pancreatic ducts, side ducts, ampulla, major papilla, minor papilla, pancreatic arteries and veins, regional lymph nodes, coeliac ganglia, and coeliac plexus.

RESULTS

The macroscopic anatomy of the pancreas was consistently visualized with PCCT. Visualization of detailed anatomy of the ductal system (including side ducts), papillae, arteries, vein, lymph nodes, and innervation was possible in 90% or more of patients with moderate to good interreader agreement.

CONCLUSION

PCCT scans of the pancreas visualizes previously unseen or inconsistently seen small anatomical structures consistently. Increased knowledge of pancreatic anatomy could have importance in imaging of pancreatic cancer and other pancreatic diseases.

Pancreatic Morphology, Immunology, and the Pathogenesis of Acute Pancreatitis

Acute pancreatitis is a complex inflammatory disorder with significant morbidity and mortality. This review aims to integrate the current knowledge of pancreatic morphology and immunology with the pathogenesis of acute pancreatitis, providing a comprehensive understanding of this critical condition. We conducted an extensive literature review, synthesizing data from recent studies and authoritative sources on pancreatic anatomy, histology, immunology, and the pathophysiology of acute pancreatitis. We also incorporated epidemiological data, clinical features, diagnostic criteria, and prognostic factors. The pancreas exhibits a complex morphology with intricate interactions between its exocrine and endocrine components. Its unique immunological landscape plays a crucial role in maintaining homeostasis and orchestrating responses to pathological conditions. In acute pancreatitis, the disruption of intracellular calcium signaling leads to premature enzyme activation, triggering a cascade of events including mitochondrial dysfunction, ATP depletion, and the release of proinflammatory mediators. This process can escalate from localized inflammation to systemic complications. The interplay between pancreatic morphology, immune responses, and pathophysiological mechanisms contributes to the varied clinical presentations and outcomes observed in acute pancreatitis. Understanding the intricate relationships between pancreatic morphology, immunology, and the pathogenesis of acute pancreatitis is crucial for developing more effective diagnostic and therapeutic strategies. This integrated approach provides new insights into the complex nature of acute pancreatitis and may guide future research directions in pancreatic disorders.

Extranodal extension influences prognosis in pancreatic body/tail cancer: A retrospective cohort study

BACKGROUND/PURPOSE

Extranodal extension (ENE) is an established prognostic factor in various malignancies, affecting survival in pancreatic head cancer (PHC). However, its significance in pancreatic body/tail cancer (PBTC) remains unclear. Therefore, we aimed to investigate the impact of ENE on PTBC prognosis.

METHODS

We analyzed data collected from electronic medical records of patients with PBTC who underwent distal pancreatectomy at a single center between January 2011 and December 2015. The patients were categorized based on ENE presence and prognostic implications were evaluated using Kaplan-Meier survival curves and Cox proportional hazards model.

RESULTS

PBTC cases involving lymph node (LN) metastasis and ENE exhibited significantly lower disease-free (DFS) and overall survival (OS) rates compared to cases without LN metastasis or ENE (median DFS; N0, 23 months; LN+/ENE-, 10 months; LN+/ENE+, 5 months; p < .001). No statistically significant difference was observed in DFS and OS rates between patients with N1/N2 in the group without ENE and those with ENE+. Multivariate analysis confirmed ENE as a significant adverse prognostic factor.

CONCLUSIONS

ENE significantly predicts poor prognosis in PBTC, particularly in cases with nodal metastasis. The current cancer staging system for PBTC should incorporate ENE status. Moreover, different staging systems should be considered for PHC and PBTC.

What is the optimal surgical approach for ductal adenocarcinoma of the pancreatic neck? - a retrospective cohort study

BACKGROUND

The appropriate surgical approach for pancreatic ductal adenocarcinoma (PDAC) is determined by the tumor's relation to the porto-mesenteric axis. Although the extent and location of lymphadenectomy is dependent on the type of resection, a pancreatoduodenectomy (PD), distal pancreatectomy (DP), or total pancreatectomy (TP) are considered equivalent oncologic operations for pancreatic neck tumors. Therefore, we aimed to assess differences in histopathological and oncological outcomes for surgical approaches in the treatment of pancreatic neck tumors.

METHODS

Patients with resected PDAC located in the pancreatic neck were identified from the National Cancer Database (2004-2020). Patients with metastatic disease were excluded. Furthermore, patients with 90-day mortality and R2-resections were excluded from the multivariable Cox-regression analysis.

RESULTS

Among 846 patients, 58% underwent PD, 25% DP, and 17% TP with similar R0-resection rates (p = 0.722). Significant differences were observed in nodal positivity (PD:44%, DP:34%, TP:57%, p < 0.001) and mean-number of examined lymph nodes (PD:17.2 ± 10.4, DP:14.7 ± 10.5, TP:21.2 ± 11.0, p < 0.001). Furthermore, inadequate lymphadenectomy (< 12 nodes) was observed in 30%, 44%, and 19% of patients undergoing PD, DP, and TP, respectively (p < 0.001). Multivariable analysis yielded similar overall survival after DP (HR:0.83, 95%CI:0.63-1.11), while TP was associated with worse survival (HR:1.43, 95%CI:1.08-1.89) compared to PD.

CONCLUSION

While R0-rates are similar amongst all approaches, DP is associated with inadequate lymphadenectomy which may result in understaging disease. However, this had no negative influence on survival. In the premise that an oncological resection of the pancreatic neck tumor is feasible with a partial pancreatectomy, no benefit is observed by performing a TP.

Repositioning the Early Pathology of Type 1 Diabetes to the Extraislet Vasculature

Type 1 diabetes (T1D) is a prototypic T cell-mediated autoimmune disease. Because the islets of Langerhans are insulated from blood vessels by a double basement membrane and lack detectable lymphatic drainage, interactions between endocrine and circulating T cells are not permitted. Thus, we hypothesized that initiation and progression of anti-islet immunity required islet neolymphangiogenesis to allow T cell access to the islet. Combining microscopy and single cell approaches, the timing of this phenomenon in mice was situated between 5 and 8 wk of age when activated anti-insulin CD4 T cells became detectable in peripheral blood while peri-islet pathology developed. This "peri-insulitis," dominated by CD4 T cells, respected the islet basement membrane and was limited on the outside by lymphatic endothelial cells that gave it the attributes of a tertiary lymphoid structure. As in most tissues, lymphangiogenesis seemed to be secondary to local segmental endothelial inflammation at the collecting postcapillary venule. In addition to classic markers of inflammation such as CD29, V-CAM, and NOS, MHC class II molecules were expressed by nonhematopoietic cells in the same location both in mouse and human islets. This CD45- MHC class II+ cell population was capable of spontaneously presenting islet Ags to CD4 T cells. Altogether, these observations favor an alternative model for the initiation of T1D, outside of the islet, in which a vascular-associated cell appears to be an important MHC class II-expressing and -presenting cell.

Unraveling Proto-Oncogene (ErbB2) Expression in Patients With Carcinoma Head of Pancreas and Chronic Pancreatitis Patients: A Case-Control Study

Background The pre-malignant tendency of the normal, non-affected portion of the pancreas is not as well explored as the multicentricity documented in pancreatic cancer cases. In order to ascertain the expression of inflammatory markers and Erythroblastic Oncogene B (ErbB2) in the non-affected pancreas in patients with pancreatic cancer, a case-control study was carried out. Materials and methods In patients who underwent pancreatoduodenectomy for pancreatic cancer (PC), pro-inflammatory genes and a tumor marker, erythroblastic oncogene 2 (ErbB2) in the epidermal growth factor receptor family were analyzed in the pancreatic tissue at the cut surface of the normal pancreas using qRT-PCR. Twenty patients diagnosed with Chronic pancreatitis (CP) after Frey's surgical procedure were selected, and their pancreatic tissues were analyzed as controls. The HPLC-purified primers were designed using National Center for Biotechnology Information (NCBI) software. The primer's specificity was verified for gene expression analysis using the Basic Local Alignment Search Tool (BLAST). The genes under study were normalized using β-actin as the housekeeping gene, and the 2-ddct method was used to compute the fold change compared to the control sample. Results Patients with margin-positive were not included. Pro-inflammatory genes (TNF-α, NF-kβ, and COX-2) had significantly lower foldchange in PC patients compared to the CP group. The CP control group had higher levels of IL-6 gene expression than the PC group. Patients with pancreatic cancer had a considerably higher expression of the ErbB2 gene than patients with CP. Conclusion The upregulated ErbB2 gene in the unaffected pancreatic tissue of pancreatic cancer patients, when compared to controls, indicates that the remaining pancreas may have the capacity to cause cancer. Proto-oncogene may play a role in the pathophysiologic process in patients with pancreatic cancer.

Prognostic impact of the distance from the root of splenic artery to tumor in the patients with pancreatic body or tail cancer

BACKGROUND

The impact of the distance from the root of splenic artery to tumor (DST) on the prognosis and optimal surgical procedures in the patients with pancreatic body/tail cancer has been unclear.

METHODS

We retrospectively analyzed 94 patients who underwent distal pancreatectomy (DP) and 17 patients who underwent DP with celiac axis resection (DP-CAR) between 2008 and 2018.

RESULTS

The 111 patients were assigned by DST length (in mm) as DST = 0: n = 14, 0

CONCLUSIONS

DST did not affect prognosis in patients with pancreatic body/tail cancer. Neoadjuvant therapy followed by DP may be desirable for patients with a DST = 0 tumor. For those with a 0 Collapse

Key Words

• Distal pancreatectomy
• Distal pancreatectomy with celiac axis resection
• Neoadjuvant therapy
• Pancreatic cancer
• Root of splenic artery

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MESH Headings

• Humans
• Splenic Artery/surgery
• Prognosis
• Retrospective Studies
• Neoplasm Recurrence, Local/pathology
• Celiac Artery/surgery
• Celiac Artery/pathology
• Pancreatic Neoplasms/pathology
• Pancreatectomy/methods

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Affiliation(s)

Takuya Minagawa Division of Hepato-Biliary-Pancreatic Surgery, Shizuoka Cancer Center, Shizuoka, Japan; Department of Hepato-Biliary-Pancreatic and Gastrointestinal Surgery, School of Medicine, International University of Health and Welfare, Chiba, Japan
Yukiyasu Okamura Division of Hepato-Biliary-Pancreatic Surgery, Shizuoka Cancer Center, Shizuoka, Japan; Division of Digestive Surgery, Department of Surgery, Nihon University School of Medicine, Tokyo, Japan.
Teiichi Sugiura Division of Hepato-Biliary-Pancreatic Surgery, Shizuoka Cancer Center, Shizuoka, Japan
Takaaki Ito Division of Hepato-Biliary-Pancreatic Surgery, Shizuoka Cancer Center, Shizuoka, Japan
Yusuke Yamamoto Division of Hepato-Biliary-Pancreatic Surgery, Shizuoka Cancer Center, Shizuoka, Japan
Ryo Ashida Division of Hepato-Biliary-Pancreatic Surgery, Shizuoka Cancer Center, Shizuoka, Japan
Katsuhisa Ohgi Division of Hepato-Biliary-Pancreatic Surgery, Shizuoka Cancer Center, Shizuoka, Japan
Keiko Sasaki Division of Pathology, Shizuoka Cancer Center, Shizuoka, Japan
Katsuhiko Uesaka Division of Hepato-Biliary-Pancreatic Surgery, Shizuoka Cancer Center, Shizuoka, Japan

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Clinicoradiological Factors Predicting Lymph Node Metastasis in Patients with Nonfunctioning Pancreatic Neuroendocrine Neoplasms: A Systematic Review and Meta-Analysis

INTRODUCTION

Lymph node metastasis of nonfunctioning pancreatic neuroendocrine neoplasms (pNENs) potentially leads to poor survival. Given the contradictory results in the literature regarding factors associated with lymph node metastasis of nonfunctioning pNENs, we conducted a systematic review and meta-analysis to determine the preoperative predictors of lymph node metastasis.

METHODS

Original studies reporting factors associated with lymph node metastasis in patients with nonfunctioning pNENs were identified in PubMed, EMBASE, and Cochrane Library databases, and data from eligible studies were analyzed using random-effects meta-analysis to obtain pooled estimates of odds ratios (ORs) and their 95% confidence intervals (CIs).

RESULTS

Eleven studies were included. Tumor size (>2 cm or >2.5 cm; OR, 5.80 [95% CI, 4.07-8.25]) and pancreatic head location (OR, 1.75 [95% CI, 1.05-2.94]) were significant preoperative predictors of lymph node metastasis. Old age (OR, 1.07 [95% CI, 0.68-1.68]) and male sex (OR, 1.12 [95% CI, 0.74-1.70]) were not significantly associated with lymph node metastasis.

CONCLUSIONS

A large tumor size and pancreatic head location can be useful for planning optimal treatment in patients with nonfunctioning pNENs.

Pancreatic draining lymph nodes (PLNs) serve as a pathogenic hub contributing to the development of type 1 diabetes

Type 1 diabetes (T1D) is a chronic, progressive autoinflammatory disorder resulting from the breakdown of self-tolerance and unrestrained β cell-reactive immune response. Activation of immune cells is initiated in islet and amplified in lymphoid tissues, especially those pancreatic draining lymph nodes (PLNs). The knowledge of PLNs as the hub of aberrant immune response is continuously being replenished and renewed. Here we provide a PLN-centered view of T1D pathogenesis and emphasize that PLNs integrate signal inputs from the pancreas, gut, viral infection or peripheral circulation, undergo immune remodeling within the local microenvironment and export effector cell components into pancreas to affect T1D progression. In accordance, we suggest that T1D intervention can be implemented by three major ways: cutting off the signal inputs into PLNs (reduce inflammatory β cell damage, enhance gut integrity and control pathogenic viral infections), modulating the immune activation status of PLNs and blocking the outputs of PLNs towards pancreatic islets. Given the dynamic and complex nature of T1D etiology, the corresponding intervention strategy is thus required to be comprehensive to ensure optimal therapeutic efficacy.

Drug Delivery Strategies for the Treatment of Pancreatic Cancer

Pancreatic cancer is fast becoming a global menace and it is projected to be the second leading cause of cancer-related death by 2030. Pancreatic adenocarcinomas, which develop in the pancreas' exocrine region, are the predominant type of pancreatic cancer, representing about 95% of total pancreatic tumors. The malignancy progresses asymptomatically, making early diagnosis difficult. It is characterized by excessive production of fibrotic stroma known as desmoplasia, which aids tumor growth and metastatic spread by remodeling the extracellular matrix and releasing tumor growth factors. For decades, immense efforts have been harnessed toward developing more effective drug delivery systems for pancreatic cancer treatment leveraging nanotechnology, immunotherapy, drug conjugates, and combinations of these approaches. However, despite the reported preclinical success of these approaches, no substantial progress has been made clinically and the prognosis for pancreatic cancer is worsening. This review provides insights into challenges associated with the delivery of therapeutics for pancreatic cancer treatment and discusses drug delivery strategies to minimize adverse effects associated with current chemotherapy options and to improve the efficiency of drug treatment.

Use of indocyanine green near-infrared lymphography to detect sentinel lymph nodes in a dog with a malignant insulinoma: a case report

Malignant insulinoma is the most common type of neuroendocrine tumor found in the pancreas of dogs. Canine insulinoma displays malignant behavior with a high rate of metastasis. The most common sites of metastases are the draining lymph nodes, which are also the primary location sites for the recurrence of functional disease. However, identifying metastatic nodes can often be complicated, as the pancreas is drained by numerous lymphatic centers, and clinical enlargement or structural changes may not always be present in metastatic nodes. Additionally, unaltered nodes are frequently small (a few millimeters) and can be hard to distinguish from the surrounding tissues. Therefore, lymphadenectomy is generally recommended for affected dogs. Unlike in human medicine, there are currently no established strategies for lymph node resection in dogs with malignant insulinoma. This report presents a technique for identifying and removing sentinel nodes using indocyanine green and near-infrared lymphography (NIRFL) during surgery. A total of six sentinel nodes were detected and resected with this method. This technique could provide a more structured approach for lymph node resection in affected dogs and potentially in humans in the future. However, its therapeutic benefits must be evaluated in a larger cohort of cases.

Cell Dissemination in Pancreatic Cancer

Pancreatic cancer is a disease notorious for its high frequency of recurrence and low survival rate. Surgery is the most effective treatment for localized pancreatic cancer, but most cancer recurs after surgery, and patients die within ten years of diagnosis. The question persists: what makes pancreatic cancer recur and metastasize with such a high frequency? Herein, we review evidence that subclinical dormant pancreatic cancer cells disseminate before developing metastatic or recurring cancer. We then discuss several routes by which pancreatic cancer migrates and the mechanisms by which pancreatic cancer cells adapt. Lastly, we discuss unanswered questions in pancreatic cancer cell migration and our perspectives.

Visible Lymph Affluents in the D3 Volume: An MDCTA Pictorial Essay

BACKGROUND

There seems to be a gap in knowledge of the anatomy of mesenteric lymphatics between the superior mesenteric nodes and the intestinal trunk. To our knowledge, these central lymph vessels were not hitherto systematically searched for, described, or morphometrically analyzed. Our aim was to identify those vessels on the routine multidetector computerized tomography angiography (MDCTA), performed prior to right colectomy for cancer, with extended mesenterectomy, central vascular ligation, and D3 lymphadenectomy.

METHODS

A total of 420 MDCTA datasets were analyzed utilizing manual segmentation and 3D reconstruction, with the aid of image processing software Osirix, Mimics, and 3-matic. The 3D models and masks underwent a detailed topographic and morphometric analysis.

RESULTS

Significant vascular-like structures, having neither origin nor termination on the blood vessels, were noted in 18 cases (4.3%) in the D3 volume. The dimensions of visible lymph vessels varied, their mean diameter was 1.81 ± 0.61 mm, and the mean length was 38.07 ± 22.19 mm. In the vast majority of cases, the lymph vessels were situated in front of the superior mesenteric artery (SMA), coursing either longitudinally cranially (13 cases) or transversely/obliquely to the left (5 cases). In all cases but one, the lymph vessel passed at the left-hand side of the middle colic artery. As for the course shape, in seven cases, the lymph vessel appeared highly serpiginous.

CONCLUSIONS

The regular MDCTA can provide valuable information on mesenteric lymphatics and aid in surgical planning.

The Pancreas and Known Factors of Acute Pancreatitis

Pancreatitis is regarded by clinicians as one of the most complicated and clinically challenging of all disorders affecting the abdomen. It is classified on the basis of clinical, morphological, and histological criteria. Causes of acute pancreatitis can easily be identified in 75–85% of patients. The main causes of acute, recurrent acute, and chronic pancreatitis are gallstone migration and alcohol abuse. Other causes are uncommon, controversial, or unexplained. For instance, cofactors of all forms of pancreatitis are pancreas divisum and hypertriglyceridemia. Another factor that should be considered is a complication of endoscopic retrograde cholangiopancreatography: post-endoscopic retrograde cholangiopancreatography acute pancreatitis. The aim of this study is to present the known risk factors for acute pancreatitis, beginning with an account of the morphology, physiology, and development of the pancreas.

Optimal lymph-node dissection for pancreatic tail cancer

PURPOSE

The optimal range of lymph-node dissection for pancreatic tail cancer remains unclear. We investigated the location and frequency of lymph-node metastases to identify the correct range of lymph-node dissection for pancreatic tail cancer.

METHODS

We analyzed clinical data retrospectively, on patients who underwent distal pancreatectomy for resectable left-sided pancreatic cancer, between February, 2006 and March, 2021. Eligible patients were divided into two groups according to the tumor location: those with pancreatic tail cancer (Pt group) and those with pancreatic body or body and tail cancer (non-Pt group).

RESULTS

Of the 96 patients analyzed, 61 (64%) were assigned to the Pt group and 35 (36%) were assigned to the non-Pt group. Metastases to stations 7, 8, 9, 10, 11, 14, and 18 were found in 0 (0%), 0 (0%), 0 (0%), 4 (7%), 18 (30%), 2 (4%), and 10 (17%) patients in the Pt group, and in 1 (3%), 4 (12%), 2 (6%), 1 (3%), 18 (51%), 3 (9%), and 6 (17%) patients in the non-Pt group, respectively.

CONCLUSION

Lymph-node dissection at stations 7, 8, and 9 might not be necessary in patients with resectable pancreatic cancer confined to the pancreatic tail.

A Comprehensive study of the Abdominal Ganglia Part 3: An overview of the most commonly observed ganglion patterns, with particular emphasis on inferior mesenteric and gonadal ganglia

INTRODUCTION

Chronic pain from untreatable abdominal cancers or pancreatitis can severely decrease an individual's quality of life due to accompanying neuropathic pain, the most difficult pain mechanism to treat. Current treatment modalities focus on peripheral block or neurolysis procedures of the sympathetic ganglia in an attempt to curb the pain and improve quality of life. Reports indicated that these treatments are ineffective with patients either experiencing no relief or return the pain in a few weeks. The aim of this study was to investigate the location, macro- and microscopic morphology and interconnections of the abdominal ganglia.

METHODS

The abdominal sympathetic ganglia of nine adult cadavers were investigated. The locations, morphology, interconnections and microscopic structure was studied in 108 potential abdominal ganglia. Particular emphasis was placed on direct interconnectivity between the ganglia and histological morphology.

RESULTS

A total of 100 ganglia were confirmed histologically to contain ganglion cells. The number and locations of most of the ganglia identified in our study does not correspond to that described by previous reports. Numerous interconnections between the different ganglia, as well as direct communications with the lumbar sympathetic chain ganglia were observed.

CONCLUSIONS

The interconnections and presence of ganglion cells the nerves connecting the ganglia lead to the belief that the system should be considered as a unit and that pain fibers may be transmitted via alternative previously undiscovered pathways. If the pain treatments are to be reassessed with this information in mind, we believe that greater success could be achieved. This article is protected by copyright. All rights reserved.

Importance of Nodal Metastases Location in Pancreatoduodenectomy for Pancreatic Ductal Adenocarcinoma: Results from a Prospective, Lymphadenectomy Protocol

BACKGROUND

Implementing a prospective lymphadenectomy protocol, we investigated the nodal yields and metastases per anatomical stations and nodal echelon following upfront pancreatoduodenectomy (PD) for cancer. Next, the relationship between the extension of nodal dissection, the number of examined and positive nodes (ELN/PLN), disease staging and prognosis was assessed.

METHODS

Lymphadenectomy included stations 5, 6, 8a-p, 12a-b-p, 13, 14a-b, 17, and jejunal mesentery nodes. Data were stratified by N-status, anatomical stations, and nodal echelons. First echelon was defined as stations embedded in the main specimen and second echelon as stations sampled as separate specimens. Recurrence and survival analyses were performed by using standard statistics.

RESULTS

Overall, 424 patients were enrolled from June 2013 through December 2018. The median number of ELN and PLN was 42 (interquartile range [IQR] 34-50) and 4 (IQR 2-8). Node-positive patients were 88.2%. The commonest metastatic sites were stations 13 (77.8%) and 14 (57.5%). The median number of ELN and PLN in the first echelon was 28 (IQR 23-34) and 4 (IQR 1-7). While first-echelon dissection provided enough ELN for optimal nodal staging, the aggregate rate of second-echelon metastases approached 30%. Nodal-related factors associated with recurrence and survival were N-status, multiple metastatic stations, metastases to station 14, and jejunal mesentery nodes.

CONCLUSIONS

First-echelon dissection provides adequate number of ELN for optimal staging. Nodal metastases occur mostly at stations 13/14, although second-echelon involvement is frequent. Only station 14 and jejunal mesentery nodes involvement was prognostically relevant. This latter station should be included in the standard nodal map and analyzed pathologically.

A Comprehensive study of the Abdominal Ganglia Part 1: Celiac, phrenic and superior mesenteric ganglia

INTRODUCTION

Patients with pancreatic cancer, chronic pancreatitis and other abdominal pain syndromes may develop debilitating pain throughout the course of their illness with little to no relief by most conventional methods. While some form of relief is experienced by patients, not all benefit from these procedures and side effects, while transitory in most cases are severe and often not expected. Our aim was therefore to investigate the anatomy surrounding the abdominal sympathetic ganglia, the target for the invasive procedures in an attempt to understand the variations in results.

MATERIALS AND METHODS

The abdominal cavities of nine individuals were dissected and the ganglia investigated, harvested and histologically and immunochemical stained.

RESULTS

The phrenic ganglion was found inconsistently and more often in the left than the right. If present it was located in association with the inferior phrenic artery and often connected to the celiac ganglion. The celiac ganglion was located anterior to the diaphragmatic crus on both sides and specifically posteromedial to the suprarenal gland and superior to the renal artery on the left. On the right it was located posterior to the suprarenal gland and inferior vena cava also superior to the renal vessels. The superior mesenteric ganglion was only positively identified in one individual and was located on the left lateral aspect of the superior mesenteric artery.

CONCLUSION

The blockade procedures for treatment of pain are developed to target the area around the celiac artery where the ganglion is commonly described to be located. However, based on our results of its location and interconnections the ganglion is not located in the targeted area.

The lymphatic system and sentinel lymph nodes: conduit for cancer metastasis

The lymphatic system is a complicated system consisting of the lymphatic vessels and lymph nodes draining the extracellular fluid containing cellular debris, excess water and toxins to the circulatory system. The lymph nodes serve as a filter, thus, when the lymph fluid returns to the heart, it is completely sterile. In addition, the lymphatic system includes the mucosa-associated lymphoid tissue, such as tonsils, adenoids, Peyers patches in the small bowel and even the appendix. Taking advantage of the drainage system of the lymphatics, cancer cells enter the lymphatic vessels and then the lymph nodes. In general, the lymph nodes may serve as a gateway in the majority of cases in early cancer. Occasionally, the cancer cells may enter the blood vessels. This review article emphasizes the structural integrity of the lymphatic system through which cancer cells may spread. Using melanoma and breast cancer sentinel lymph node model systems, the spread of early cancer through the lymphatic system is progressive in a majority of cases. The lymphatic systems of the internal organs are much more complicated and difficult to study. Knowledge from melanoma and breast cancer spread to the sentinel lymph node may establish the basic principles of cancer metastasis. The goal of this review article is to emphasize the complexity of the lymphatic system. To date, the molecular mechanisms of cancer spread from the cancer microenvironment to the sentinel lymph node and distant sites are still poorly understood and their elucidation should take major priority in cancer metastasis research.

Resection of the Portal-Superior Mesenteric Vein in Pancreatic Cancer: Pathological Assessment and Recurrence Patterns

OBJECTIVES

The portal vein (PV)-superior mesenteric vein (SMV) margin is the most affected margin in pancreatic cancer. This study investigates the association between venous resection, tumor invasion in the resected PV-SMV, recurrence patterns, and overall survival (OS).

METHODS

This multicenter cohort study included patients who underwent pancreatoduodenectomy for pancreatic cancer (2010-2017). In addition, a systematic literature search was performed.

RESULTS

In total, 531 patients were included, of which 149 (28%) underwent venous resection of whom 53% had tumor invasion in the resected PV-SMV. Patients with venous resection had a significant higher rate of R1 margins (69% vs 37%) and had more often multiple R1 margins (43% vs 16%). Patient with venous resection had a significant shorter time to locoregional recurrence and a shorter OS (15 vs 19 months). At multivariable analyses, venous resection and tumor invasion in the resected PV-SMV were not predictive for time to recurrence and OS. The literature overview showed that pathological assessment of the resected PV-SMV is not adequately standardized.

CONCLUSIONS

Only half of patients with venous resection had pathology confirmed tumor invasion in the resected PV-SMV, and both are not independently associated with time to recurrence and OS. The pathological assessment of the resected PV-SMV needs to be standardized.

Clinical Implication of Node-negative Resectable Pancreatic Cancer

BACKGROUND

Lymph node metastasis is one of the strongest prognostic factors of pancreatic cancer. However, the clinical implication of pathologically node-negative pancreatic cancer (pN0-PC) has not been fully investigated.

METHODS

Patients who underwent surgical resection for radiologically resectable pancreatic cancer between 2002 and 2018 were included in this study. A clinicopathological examination focusing on pN0-PC was performed.

RESULTS

Of all 533 patients, 155 (29.1%) were diagnosed with pN0-PC and 378 (70.9%) were diagnosed with node-positive pancreatic cancer (pN1/2-PC). The 5-year survival rates of patients with pN0-PC and pN1/2-PC were 57.1% and 25.0%, respectively (p < 0.001). A multivariate analysis revealed six prognostic factors in pN0-PC: age ≥ 70 years, nonadministration of adjuvant chemotherapy, anterior serosal invasion, nerve plexus invasion, and microscopic lymphatic and venous invasions. The 5-year survival rates of patients who had pN0-PC with 0-1 risk factor, with 2-3 risk factors, and with 4-6 risk factors were 87.6%, 47.9%, and 16.4%, respectively. Survival of patients who had pN0-PC with 4-6 risk factors was comparable to that of pN1/2 patients. The diagnostic capability of metastasis-negative lymph node was unsatisfactory, with a predictive value of < 43%.

CONCLUSIONS

Although the prognosis of patients with pN0-PC was better than that of patients with pN1/2-PC, it is not satisfactory. Survival of patients who had pN0-PC with 0-1 risk factors was extremely favorable; however, survival of patients who had pN0-PC with 4-6 risk factors was similar to those with pN1/2-PC.

Pancreas Optical Clearing and 3-D Microscopy in Health and Diabetes

Although first described over a hundred years ago, tissue optical clearing is undergoing renewed interest due to numerous advances in optical clearing methods, microscopy systems, and three-dimensional (3-D) image analysis programs. These advances are advantageous for intact mouse tissues or pieces of human tissues because samples sized several millimeters can be studied. Optical clearing methods are particularly useful for studies of the neuroanatomy of the central and peripheral nervous systems and tissue vasculature or lymphatic system. Using examples from solvent- and aqueous-based optical clearing methods, the mouse and human pancreatic structures and networks will be reviewed in 3-D for neuro-insular complexes, parasympathetic ganglia, and adipocyte infiltration as well as lymphatics in diabetes. Optical clearing with multiplex immunofluorescence microscopy provides new opportunities to examine the role of the nervous and circulatory systems in pancreatic and islet functions by defining their neurovascular anatomy in health and diabetes.

Distal pancreatectomy for pancreatic neoplasia: is splenectomy really necessary? A bicentric retrospective analysis of surgical specimens

BACKGROUND

While distal pancreatectomy with splenectomy (DPS) is the reference treatment for pancreatic body and tail neoplasia, oncological benefits of splenectomy have never been demonstrated. Involvement of spleen, splenic hilum and lymph nodes (LN) was therefore assessed on DPS specimens.

METHODS

All DPS pancreatic neoplasia specimens obtained in 2 Brussels University Hospitals over 15 years (2004-2018) were reviewed retrospectively, using both preoperative radiological imaging and postoperative pathological analyses of splenic parenchyma, hilar tissue and LN.

RESULTS

The total of 130 DPS specimens included 85 adenocarcinomas, 37 neuroendocrine neoplasms and 8 other carcinomas. Tumours involved the pancreatic body without tail invasion for 59 specimens (B, Body group), and the pancreatic tail with/without body for 71 (T, Tail group). At pathology, direct splenic and/or hilar involvement was observed in 13 T specimens (13/71, 18.3%), but in none belonging to the Body group. The observed numbers of splenic hilar LN (only reported in 49/130 patients) were low, only one T adenocarcinoma had positive splenic LN in addition to direct splenic involvement.

CONCLUSION

Splenectomy remains justified during pancreatectomy for neoplasia involving the pancreatic tail, but in case of pancreatic body tumours, its benefits should be questioned in the light of absent splenic LN/parenchymal involvement.

Endocrine and Metabolic Insights from Pancreatic Surgery

Although it is well established that diabetes can also develop as a result of diseases or maneuvers on the exocrine pancreas, the complex relationship between glucose disorders and underlying pancreatic disease is still debated. There is evidence that several features linked to pancreatic diseases can modify endocrine and metabolic conditions before and after surgery. However, pancreatic surgery provides a rare opportunity to correlate in vivo endocrine and metabolic pathways with ex vivo pancreatic samples, to examine the endocrine and metabolic effects of acute islet removal, and finally to clarify the pathogenesis of diabetes. This approach could therefore represent a unique method to shed light on the molecular mechanisms, predicting factors, and metabolic consequences of insulin resistance, islet plasticity, β cell failure, and type 2 diabetes.

Lymphatic vessel remodeling and invasion in pancreatic cancer progression

Background

The lymphatic system is involved in metastasis in pancreatic cancer progression. In cancer staging, lymphatic spread has been used to assess the invasiveness of tumor cells. However, from the endothelium's perspective, the analysis downplays the peri-lesional activities of lymphatic vessels. This unintended bias is largely due to the lack of 3-dimensional (3-D) tissue information to depict the lesion microstructure and vasculature in a global and integrated fashion.

Methods

We targeted the pancreas as the model organ to investigate lymphatic vessel remodeling in cancer lesion progression. Transparent pancreases were prepared by tissue clearing to facilitate deep-tissue, tile-scanning microscopy for 3-D lymphatic network imaging.

Findings

In human pancreatic ductal adenocarcinoma, we identify the close association between the pancreatic intraepithelial neoplasia (PanIN) lesions and the lymphatic network. In mouse models of PanIN (elastase-CreER;LSL-Kras^G12D and elastase-CreER;LSL-Kras^G12D;p53^+/−), the 3-D image data reveal the peri-lesional lymphangiogenesis, endothelial invagination, formation of the bridge/valve-like luminal tubules, vasodilation, and luminal invasion. In the orthotopic mouse model of pancreatic cancer, we identify the localized, graft-induced lymphangiogenesis and the peri- and intra-tumoral lymphatic vessel invasion.

Interpretation

The integrated view of duct lesions and vascular remodeling suggests an active role, rather than a passive target, of lymphatic vessels in the metastasis of pancreatic cancer. Our 3-D image data provide insights into the pancreatic cancer microenvironment and establish the technical and morphological foundation for systematic detection and 3-D analysis of lymphatic vessel invasion.

Fund

Taiwan Academia Sinica (AS-107-TP-L15 and AS-105-TP-B15), Ministry of Science and Technology (MOST 106-2321-B-001-048, 106-0210-01-15-02, 106-2321-B-002-034, and 106-2314-B-007-004-MY2), and Taiwan National Health Research Institutes (NHRI EX107-10524EI).

Exploration of peripancreatic lymphatic pathways in a live porcine model

Pancreatic cancer is associated with a poor prognosis, mainly due to lymph node invasion and lymph node recurrence after surgical resection, even after extended lymphadenectomy. The peripancreatic lymphatic system is highly complex and the specific lymphatic drainage of each part of the pancreas has not been established. The aim of this study was to determine the lymphatic drainage pathways specific to each part of the pancreas on live pigs using Patent Blue. The pancreases of 14 live pigs were injected in different parts of the gland. The technique was efficient and reproducible. The diffusion patterns were similar for each location and were reported. Our results in pigs allowed us to define specific nodal relay stations and lymphatic drainage for each part of the pancreas and confirm that independent anatomical-surgical pancreatic segments can be described. It is interesting to note that lymphatic drainage for the upper part of the proximal part of pancreas (duodenal lobe) occurred on the left side of the portal vein. This suggests that lymph node resection during cephalic duodenopancreatectomy in humans should be extended to the left side of the mesenteric vein, and probably to the right side of the superior mesenteric artery, as recently suggested. These results could help surgeons perform safe anatomical-segmental pancreatic resections with accurate lymphadenectomies and improve survival in patients with pancreatic cancer. Based on these results we will perform an innovative prospective study. Patent Blue will be injected into different parts of the gland in patients operated for pancreatic resection, and lymphatic diffusion of the dye will be recorded in relation to their origin from the theoretical pancreatic segments (ClinicalTrials.gov Identifier: NCT03597230).

Immune heterogeneity of head and tail pancreatic lymph nodes in non-obese diabetic mice

The pancreatic lymph node is critical to the pathogenesis of autoimmune diabetes, as it constitutes the initial site for the priming of autoreactive T cells. In this study, we compared the histopathology of the head pancreatic lymph node (HPLN) to the tail pancreatic lymph node (TPLN) in NOD mice. HPLNs and TPLNs were harvested from 4 week-, 8 week-, and 12 week-old NOD mice, and their microvasculature, extracellular matrix, and immune cell subsets were characterized. The percentages of B cells and antigen-presenting cells (APCs) were much higher in the HPLN, as compared to the TPLN. Notably, the HPLNs of 12 week-old mice were characterized by greater expansion of high endothelial venules (HEVs) and lymphatic vessels in comparison to the TPLNs. Finally, we observed a higher density of extracellular matrix (ECM) fibers surrounding the lymphatic vasculature in the HPLNs than in the TPLNs. These data for the first time demonstrate that the HPLN possesses a different immune microanatomy and organization from the TPLN. These novel observations unveil a major phenotypic difference between two types of LNs from the same organ and may highlight an independent fundamental role played by each PLN during the establishment of T1D.

Staging of pancreatic cancer: resectable, borderline resectable, and unresectable disease

Pancreatic ductal adenocarcinoma (PDAC) is a relatively common malignancy that carries an overall poor prognosis, with five-year survival below 10%. Despite ongoing research, surgical resection remains the only potentially curative treatment. Therefore, accurate identification of those patients who would benefit from surgical resection is of paramount importance. High-quality imaging and image interpretation is central to this process. Radiology helps in the determination of whether patients are resectable, borderline resectable, or unresectable and guides treatment planning.

Should a standard lymphadenectomy include the No. 9 lymph nodes for body and tail pancreatic ductal adenocarcinoma?

OBJECTIVES

This study aimed to use a retrospective data base to investigate whether a standard lymphadenectomy during distal pancreatectomy should include the No. 9 lymph nodes (LNs) for resectable pancreatic ductal adenocarcinoma (PDAC) located in the body and tail of the pancreas.

METHODS

Data from 169 patients undergoing curative distal pancreatectomy for PDAC between Jan 1, 2013 and Dec 31, 2016 were collected. According to the tumor location, patients were divided into three groups: pancreatic neck tumor, pancreatic body and tail tumor with margin-to-bifurcation-distance (MTBD) ≤ 2.5 cm and pancreatic body and tail tumor with MTBD > 2.5 cm. The metastatic rate of the No. 9 LNs was compared among the 3 groups. The survival outcomes were analyzed.

RESULTS

The involvement rate for No. 9 LNs was 20.7% (6/29) for pancreatic neck tumors, 17.6% (15/85) for body and tail tumors with MTBD ≤ 2.5 cm and 1.8% (1/55) for MTBD > 2.5 cm. The No. 9 LNs were significantly more frequently involved in neck or body and tail tumors with MTBD ≤2.5 cm than with the cases with MTBD >2.5 cm (OR 0.082, P = 0.016). No. 9 LN involvement was not associated with worse survival compared with survival associated with involvement of other LNs (P = 0.780).

CONCLUSIONS

For PDAC located in the neck or in the body and tail of the pancreas with MTBD ≤ 2.5 cm, the involvement rate for No. 9 LNs is high. Standard lymphadenectomy should include the No. 9 LNs.

Lymphatic Vessel Network Structure and Physiology

The lymphatic system is comprised of a network of vessels interrelated with lymphoid tissue, which has the holistic function to maintain the local physiologic environment for every cell in all tissues of the body. The lymphatic system maintains extracellular fluid homeostasis favorable for optimal tissue function, removing substances that arise due to metabolism or cell death, and optimizing immunity against bacteria, viruses, parasites, and other antigens. This article provides a comprehensive review of important findings over the past century along with recent advances in the understanding of the anatomy and physiology of lymphatic vessels, including tissue/organ specificity, development, mechanisms of lymph formation and transport, lymphangiogenesis, and the roles of lymphatics in disease. © 2019 American Physiological Society. Compr Physiol 9:207-299, 2019.

Extended versus peripancreatic lymph node dissection for the treatment of left-sided pancreatic cancer

Purpose

The pathways of lymphatic metastases differ according to the tumor location in pancreatic cancer patients. However, it is unclear whether extended lymph node dissection (LND) is essential for all left-sided pancreatic cancer. The aim of this study is to evaluate the survival outcomes according to the extent of LND and tumor location in patients with left-sided pancreatic cancer.

Methods

January 2005 to December 2013, we retrospectively identified 107 patients who underwent curative intent surgery for left-sided pancreatic cancer. The left-sided pancreatic cancer was defined as a tumor located in pancreatic body or tail. The extent of LND was divided into 2 groups: extended LND and peripancreatic LND. The extended LND group included celiac and superior mesenteric LNs.

Results

We included 107 patients with left-sided pancreatic cancer; 59 patients with pancreatic body cancer and 48 patients with pancreatic tail cancer. The median follow-up period was 17 months (range, 3–110 months). Fifty patients with pancreatic body cancer and 30 patients with pancreatic tail cancer underwent extended LND. In patients with pancreatic body cancer, extended LND was associated with improved disease-free survival (DFS) (P = 0.010) and overall survival (P = 0.014). However, extended LND was not associated with DFS in patients with pancreatic tail cancer.

Conclusion

Extended LND could improve survival in patients with pancreatic body cancer. However, extended LND had no survival benefit for the treatment of pancreatic tail cancer.

Anatomo-radiological patterns of pancreatic vascularization, with surgical implications: Clinical and anatomical study

The pancreas receives multiple arterial sources that should be considered in patients undergoing pancreatic surgery. The aim of this study is to describe pancreatic vascularization and to explore the anatomical basis of postoperative complications. Ten specimens from unembalmed cadavers, including the retroperitoneal vessels and organs and spleen, were injected with acrylic resins to obtain vascular casts. Thirty computed tomography angiographies (CTA) of subjects with no pancreatic pathology (mean age 70.9 years) were also analyzed. A paucivascular area at the neck of the pancreas was apparent in all vascular casts. At CTA: (1) the transverse pancreatic artery, the only artery running from the cervicocephalic to the somatocaudal segment, was visible in 76.9% of cases; (2) the splenic artery was suprapancreatic in 66.7% and intrapancreatic with a tortuous course in 33.3%; (3) the posterior superior pancreaticoduodenal artery was visible in 100% of cases, the anterior superior pancreatico-duodenal artery in 92.6%, the anterior inferior pancreaticoduodenal artery in 73.1%, the posterior inferior pancreaticoduodenal artery in 86.4%, the dorsal pancreatic artery in 65.4%, the great pancreatic artery in 73.1%, and the pancreatic arteries to the body and caudal pancreatic arteries in 96.2%. Our study demonstrated great individual variability of the pancreatic vasculature, which can be explored by CTA and could be relevant to surgical procedures. Clin. Anat. 30:614-624, 2017. © 2017 Wiley Periodicals, Inc.

The lymphatic system and pancreatic cancer

This review summarizes current knowledge of the biology, pathology and clinical understanding of lymphatic invasion and metastasis in pancreatic cancer. We discuss the clinical and biological consequences of lymphatic invasion and metastasis, including paraneoplastic effects on immune responses and consider the possible benefit of therapies to treat tumors that are localized to lymphatics. A review of current techniques and methods to study interactions between tumors and lymphatics is presented.