[Re-thinking of "pelvirectal space"].

Before the "mesorectal" theory was proposed, the traditional anatomy believed that the "pelvirectal space" belonged to the anal canal and perirectal space, which was independent of the rectal structure, located on both sides of the rectum, above the levator ani, and below the peritoneal reflexion, and was composed of a large amount of fatty tissue filling. With the development of the theory of membrane anatomy and the clarification of the concept of "rectal mesentery", combined with the author's clinical experience, we found that the above-mentioned fat is actually the fat within the mesorectum, as well as the fat tissue of lateral lymph nodes (LLN) such as the internal iliac lymph nodes (No.263) and obturator lymph nodes (No.283) on both sides of the rectal mesentery, rather than the so-called fat tissue within the interstitial space. Therefore, the author believes that the pelvirectal space does not exist. In the anatomical location equivalent to the pelvic rectal space, there is the "superior levator ani space" based on the membrane anatomy theory. From the pelvirectal space to the superior levator anal space, it reflects our further understanding of the anatomy of the rectal mesentery.

Differential Modulation by Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acid (DHA) of Mesenteric Fat and Macrophages and T Cells in Adipose Tissue of Obese fa/fa Zucker Rats.

Polyunsaturated fatty acids (PUFAs) can alter adipose tissue function; however, the relative effects of plant and marine n3-PUFAs are less clear. Our objective was to directly compare the n3-PUFAs, plant-based α-linolenic acid (ALA) in flaxseed oil, and marine-based eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) in high-purity oils versus n6-PUFA containing linoleic acid (LA) for their effects on the adipose tissue and oral glucose tolerance of obese rats. Male fa/fa Zucker rats were assigned to faALA, faEPA, faDHA, and faLA groups and compared to baseline fa/fa rats (faBASE) and lean Zucker rats (lnLA). After 8 weeks, faEPA and faDHA had 11-14% lower body weight than faLA. The oral glucose tolerance and total body fat were unchanged, but faEPA had less mesenteric fat. faEPA and faDHA had fewer large adipocytes compared to faLA and faALA. EPA reduced macrophages in the adipose tissue of fa/fa rats compared to ALA and DHA, while faLA had the greatest macrophage infiltration. DHA decreased (~10-fold) T-cell infiltration compared to faBASE and faEPA, whereas faALA and faLA had an ~40% increase. The n3-PUFA diets attenuated tumour necrosis factor-α in adipose tissue compared to faBASE, while it was increased by LA in both genotypes. In conclusion, EPA and DHA target different aspects of inflammation in adipose tissue.

A Unique Case of Mesenteric Gastrointestinal Stromal Tumor Presenting as an Acute Abdomen.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors in the digestive tract and arise from the interstitial cells of Cajal in the mesenteric plexus. These tumors can originate in any part of the GI tract; however, a higher burden has been observed in the stomach and small intestines. Mesenteric GISTs are exceedingly rare, with unique clinicopathological features and a poorer prognosis. Herein, we describe a unique case of a 66-year-old female with a remote history of appendectomy who presented to the emergency room complaining of severe abdominal pain and vomiting. On imaging, the patient was found to have a large inflammatory mass associated with small bowel loops, and the pathology confirmed a mesenteric GIST. The tumor was resected, and the genomic test results confirmed the KIT (exon 11) mutation. Although the tumor had a low mitotic rate, the tumor was large enough to warrant the initiation of adjuvant imatinib mesylate for 36 months with regular bloodwork and imaging.

Mesentery-Sparing Technique: a New Intracorporeal Approach for Urinary Diversion in Robot-Assisted Radical Cystectomy.

BACKGROUND: Robotic-assisted radical cystectomy (RARC) with intracorporeal urinary diversion (ICUD) is associated with significant morbidity and mortality. We present an alternative technique that preserves the complete mesenteric vascularization during the isolation of the intestinal segment used in ICUD, including distal vessels. This approach aims to minimize the risk of ischemia in both the ileal anastomosis and the isolated loop at the diversion site. METHODS: This cohort study included 31 patients, both male and female, who underwent RARC with ICUD from February 2018 to November 2023, performed by a single surgeon. Intraoperative and postoperative complications data were retrieved for analysis, employing our proposed mesentery-sparing technique in all cases. The primary endpoint was the incidence of intraoperative and postoperative complications directly attributable to the mesentery-sparing approach in ICUD. Secondary endpoints included other postoperative variables not directly related to mesentery preservation, such as the incidence of postoperative ileus requiring parenteral nutrition and the duration of hospitalization. RESULTS: None of the patients experienced intraoperative or postoperative complications directly related to mesentery-sparing, such as intestinal fistulae or internal hernias. The median duration of hospitalization was 6 days, and postoperative ileus necessitating total parenteral nutrition occurred in 19% of the patients. Minor complications (Clavien-Dindo grades I-II) accounted for 27.6% of the cases and major complications (grades III-V) accounted for 20.6%. CONCLUSION: The mesentery-sparing technique outlined herein offers an alternative method for preserving the vascularization of intestinal segments and reducing the risk of intestinal complications in ICUD during RARC.

[Experience of mesenteric sector fixation in mesenteric torsion treatment].

Objective: The preliminary results was reported regarding the treatment of mesenteric torsion by mesenteric fixation in the last decade, especially preventing recurrence of mesenteric torsion by mesenteric fan-shaped fixation. Methods: We selected 12 patients who received emergency operation in Chongqing Hospital of the First Affiliated Hospital of Guangzhou University of Chinese Medicine from December 2010 to March 2022. All of them were made a definite diagnose of mesenteric torsion by the preoperative CT scan or exploratory laparotomy. The recurrence of mesenteric torsion will be prevented by taking the operation of mesenteric fan-shaped fixation. This technique is suitable for the patient who is suffering total mesenteric torsion, but enteric necrosis is excluded affirmatively. The operation is consists of the following progress: (1) Exploratory laparotomy to check for necrosis of the bowel and for lesions other than torsion. (2) Mesenteric torsion derotation.(3) Mesenteric linear fixation; the right posterior lower border of the small mesentery (terminal ileal mesentery) is intermittently sutured to the posterior peritoneum of the right lower quadrant to increase the width of the base of the small mesentery. (4) Mesenteric fan-shaped fixation, which is fan-shaped to the lower left and fixed in the posterior peritoneum, shortening the length of the mesentery and further increasing the width of the mesentery and posterior peritoneal fixation. Results: A total of 12 patients with mesenteric torsion were treated by operation for 15 times in all. Among them, 3 cases received resection of most small bowel were performed without recurrence; 3 patients received only derotation for a total of 4 times, 2 cases recurred, 1 of them recurred twice; 4 cases underwent derotation and mesenteric linear fixation,and 1 case recurred. Four patients with derotation and mesenteric fan-shaped fixation recovered well without recurrence. Conclusion: Mesenteric fan-shaped fixation may be an effective operative type to reduce or avoid postoperative recurrence of mesenteric torsion.

Dimethyl fumarate modulates the regulatory T cell response in the mesenteric lymph nodes of mice with experimental autoimmune encephalomyelitis.

Dimethyl fumarate (DMF, Tecfidera) is an oral drug utilized to treat relapsing-remitting multiple sclerosis (MS). DMF treatment reduces disease activity in MS. Gastrointestinal discomfort is a common adverse effect of the treatment with DMF. This study aimed to investigate the effect of DMF administration in the gut draining lymph nodes cells of C57BL6/J female mice with experimental autoimmune encephalomyelitis (EAE), an animal model of MS. We have demonstrated that the treatment with DMF (7.5 mg/kg) significantly reduces the severity of EAE. This reduction of the severity is accompanied by the increase of both proinflammatory and anti-inflammatory mechanisms at the beginning of the treatment. As the treatment progressed, we observed an increasing number of regulatory Foxp3 negative CD4 T cells (Tr1), and anti-inflammatory cytokines such as IL-27, as well as the reduction of PGE2 level in the mesenteric lymph nodes of mice with EAE. We provide evidence that DMF induces a gradual anti-inflammatory response in the gut draining lymph nodes, which might contribute to the reduction of both intestinal discomfort and the inflammatory response of EAE. These findings indicate that the gut is the first microenvironment of action of DMF, which may contribute to its effects of reducing disease severity in MS patients.

Mesenteric and omental lymphatic malformations in children: seven-year surgical experience from two centers in China.

PURPOSE: To compare the clinical characteristics, surgical management and prognosis of mesenteric lymphatic malformations (ML) and omental lymphatic malformations (OL) in children. METHODS: This retrospective study included 148 ML patients and 53 OL patients who underwent surgical treatment at two centers between January 2016 and December 2022. Details about the patients' clinical characteristics, cyst characteristics, preoperative complications, surgical methods, and prognosis were retrieved and compared. RESULTS: No significant differences in sex ratio, prenatal diagnosis, or age of diagnosis were noted between ML and OL patients. Vomiting was more common in ML patients than in OL patients (46.6% vs. 22.6%, P = 0.002), but OL patients were more likely to be misdiagnosed (35.8% vs. 18.9%, P = 0.012). The size of the cysts in OL patients was significantly larger than that in ML patients (14.0 [4.0-30.0] vs. 10.0 [2.0-50.0] cm, P<0.001), and cysts with turbid fluid were more common in OL patients (38.0% vs. 20.6%, P<0.001). More OL patients than ML patients had preoperative hemorrhage or infection of cysts (41.5% vs. 31.8%, P<0.016). Cyst excision was performed in 137 (92.6%) ML patients and 51 (96.2%) OL patients, and the incidence of postoperative complications was lower (12.6% vs. 4.2%, P = 0.165) among OL patients. The main postoperative complications included adhesive ileus and recurrence of cysts. Additionally, more OL patients than ML patients were treated with laparoscopic surgery (69.8% vs. 39.2%, P<0.001). CONCLUSIONS: There were differences in clinical characteristics, cyst characteristics and preoperative complications between ML and OL patients. Cyst excision was the most common surgical method that was used to treat both ML and OL patients, and laparoscopic surgery could be a feasible surgical approach for treating OL patients with a good prognosis. TRIAL REGISTRATION: Retrospectively registered.

[A Case of Intestinal Obstruction Due to an Internal Hernia in the Mesenteric Defect after Laparoscopic Resection of Transverse Colon].

72-year-old man who was diagnosed with transverse colon cancer cT3N1aM0, Stage Ⅲb, and underwent laparoscopic- assisted resection of the transverse colon. Postoperatively, the patient was discharged from the hospital after 24 days due to complications such as paralytic ileus and intra-abdominal abscess caused by prolonged intestinal congestion. On postoperative day 91, the patient developed abdominal pain and vomiting at home, and was rushed to our hospital on the same day. Abdominal CT showed that an internal hernia had formed in the mesenteric defect after resection of the transverse colon, which was suspected to have caused obstruction of the small intestine. After adequate preoperative decompression of the intestinal tract, a laparoscopic surgery was performed on the 9th day. The operative findings were that the jejunum(100- 160 cm from the Treitz ligament)had strayed into the mesenteric defect of the transverse colon, resulting in an internal hernia. After the internal hernia was repaired laparoscopically, the mesenteric defect was closed with a 3-0 V-Loc(non- absorbable). The patient had a good postoperative course and was discharged home 6 days after surgery.

68 Ga-FAPI-04 PET/CT Imaging of Mesenteric Aggressive Fibromatosis.

ABSTRACT: Aggressive fibromatosis is a relatively rare disease. We describe 68 Ga-FAPI-04 PET/CT findings in a case of histologically proved mesenteric aggressive fibromatosis. 68 Ga-FAPI-04 PET/CT revealed a mass in the mesentery with increased FAPI activity. This case indicates that FAPI PET may be useful for evaluation of aggressive fibromatosis.

Mesenteric-based surgery for Crohn's disease: evidence and perspectives.

Postoperative anastomotic recurrence of Crohn's disease is challenging and can lead to symptom recurrence and further surgery. The mesenteric pole of the intestine is the initial site of macroscopic anastomotic recurrence, and the mesentery may play an important role in recurrence after surgical resection. Therefore, "mesenteric-based surgery" has gained increasing attention by clinicians. However, the role of mesentery in the postoperative recurrence remains controversial. This review will examine mesenteric changes in Crohn's disease, proposed roles for mesentery in disease progression, and the potential for mesenteric-based surgery in the surgical management of Crohn disease.

The mesenteric entry site as a potential weak point in gastrointestinal anastomoses - findings from an ex-vivo biomechanical analysis.

PURPOSE: Gastrointestinal disorders frequently necessitate surgery involving intestinal resection and anastomosis formation, potentially leading to severe complications like anastomotic leakage (AL) which is associated with increased morbidity, mortality, and adverse oncologic outcomes. While extensive research has explored the biology of anastomotic healing, there is limited understanding of the biomechanical properties of gastrointestinal anastomoses, which was aimed to be unraveled in this study. METHODS: An ex-vivo model was developed for the biomechanical analysis of 32 handsewn porcine end-to-end anastomoses, using interrupted and continuous suture techniques subjected to different flow models. While multiple cameras captured different angles of the anastomosis, comprehensive data recording of pressure, time, and temperature was performed simultaneously. Special focus was laid on monitoring time, location and pressure of anastomotic leakage (LP) and bursting pressures (BP) depending on suture techniques and flow models. RESULTS: Significant differences in LP, BP, and time intervals were observed based on the flow model but not on the suture techniques applied. Interestingly, anastomoses at the insertion site of the mesentery exhibited significantly higher rates of leakage and bursting compared to other sections of the anastomosis. CONCLUSION: The developed ex-vivo model facilitated comparable, reproducible, and user-independent biomechanical analyses. Assessing biomechanical properties of anastomoses offers an advantage in identifying technical weak points to refine surgical techniques, potentially reducing complications like AL. The results indicate that mesenteric insertion serves as a potential weak spot for AL, warranting further investigations and refinements in surgical techniques to optimize outcomes in this critical area of anastomotic procedures.

No difference in postprandial mesenteric blood flow between healthy younger and elderly individuals.

We recently used phase-contrast magnetic resonance imaging (PC-MRI) to demonstrate an attenuated postprandial blood flow response in the superior mesenteric artery (SMA) in patients with Parkinson's disease compared to age- and sex-matched healthy controls. Since both groups showed substantial inter-individual variations, we extended the cohort of controls with a group of young individuals to investigate possible age-related effects. Seventeen healthy young subjects aged < 30 years and 17 elderly subjects aged > 50 years underwent serial PC-MRI to measure the postprandial blood flow response in the SMA after ingestion of a standardized liquid test meal (∼400 kcal). Postprandial blood flow dynamics in SMA did not differ between young and elderly subjects. A noticeable inter-individual variation in postprandial intestinal blood flow increase was found, and approximately 30% of the variation could be explained by the preprandial blood flow. Regardless of age, some subjects showed a remarkable transient SMA blood flow increase immediately after meal intake. This study provides tentative evidence that postprandial blood flow dynamics in SMA in healthy young and elderly subjects do not substantially differ, indicating that age is without impact on vascular response in SMA as an indicator for regulation of mesenteric perfusion in response to food intake.

Age-associated reduction of sinus macrophages in human mesenteric lymph nodes.

There are numerous macrophages and dendritic cells in lymph nodes (LNs). Recent studies have highlighted that sinus macrophages (SMs) in LNs possess antigen-presenting capabilities and are related to anti-cancer immune responses. In this study, we assessed the distribution of SMs in mesenteric LNs removed during surgery for colorectal cancer. A marked reduction of SMs was noted in elderly patients, particularly those over 80 years old. We observed a disappearance of CD169-positive cells in LNs where SMs were reduced. In silico analysis of publicly available single-cell RNA sequencing data from LNs revealed that CD169-positive macrophages express numerous genes associated with antigen presentation and lymphocyte proliferation, similar to dendritic cells' functions. In conclusion, our study demonstrates that SMs, potentially crucial for immune activation, diminish in the LNs of elderly patients. This reduction of SMs may contribute to the immune dysfunction observed in the elderly.

A case of significant loss of mesenteric fat: Educational and clinical relevance.

Mesenteric fat, a type of intraperitoneal adipose tissue, plays a critical role in protection and the immune response. Loss of mesenteric fat is a known consequence of a variety of clinical conditions; however, visual documentation of this rare occurrence is not available in the literature searched. Here we report a case of significant loss of mesenteric fat identified during educational dissection of a 79-year-old male fresh frozen donor cadaver, causing the mesenteric folds to appear transparent. The gross anatomical characteristics, clinical importance, and educational significance of this abnormality are described in this report. Knowledge of this condition may be of interest to clinicians, and documentation could benefit anatomists and educators dissecting and teaching in the laboratory setting.

Cecal volvulus in complete common mesentery.

Common mesentery is an abnormal rotation of the primary umbilical loop characterized by inverted positioning of the mesenteric vessels; the mesenteric vein is displaced to the left of the artery. The inversion can be complete or incomplete. If it is incomplete, the mesenteric root is very short, with an empty right iliac fossa and the caecum in high median or subhepatic position. If it is complete, the entire small intestine is on the right, the entire large intestine is on the left; there is no third duodenum, and the second duodenum is anastomosed in the jejunum to the right of the superior mesenteric vessels. Cecal volvulus is a rarely encountered cause of acute intestinal occlusion and should be considered as a surgical emergency. There exist two main types of volvulus: by twisting of the large intestine around its axis, which remains in place; or by tilt and to rotation of the colon, which changes position.

Recurrent mucinous cystic neoplasm of the mesentery in a young nullipara mimicking as ovarian carcinoma.

INRODUCTION: Mucinous cystic neoplasms are rare tumors. They may originate from either ovaries, pancreas, or other intra-abdominal sites, but rarely from the mesentery. CASE HISTORY: A 22-year-old nulliparaous woman, who had undergone laparascopic bilateral cystectomy for recurrent ovarian mass, presented with pain in abdomen, backache, and menstrual irregularities. Provisionally diagnosed as ovarian carcinoma, she underwent bilateral salpingo-oophorectomy and sigmoid colectomy. However, the histopathological examination revealed mucinous cystic neoplasm of the mesentery. DISCUSSION: Thus, complete resection of the cysts with meticulous gross and histopathological examination remains the gold standard to differentiate mucinous cystic neoplasm (MCN) of the mesentery from its mimics, especially malignant counterparts, enabling clinicians to adequately manage such patients. Here, we present a case of recurrent MCN of mesentery (mesocolon), mimicking as ovarian carcinoma confirmed on histopathological examination, in a young adult.

[A Case of Desmoid-Type Fibromatosis of the Mesentery of Small Intestine].

Desmoid-type fibromatosis is a relatively rare disease, often associated with familial adenomatous polyposis and a history of abdominal surgery. A 43-year-old male patient presented with abdominal pain and contrast-enhanced CT showed a mass in the lower abdomen. The mass was a 4×4×3 cm white, dense tumor with a wreath-like arrangement of eosinophilic spindle-shaped cells. Immunostaining showed KIT(-), CD34(-), desmin(-), ß-catenin(+), SMA(few+), and the diagnosis was desmoid-type fibrosis. Six months after surgery, there was no apparent recurrence.