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.

Mesenteric cystic lymphangioma in adults: a rare entity presenting as acute abdomen - a report of two cases

Lymphangiomas are rare benign tumors that mainly involve the head and neck region in pediatric patients. Lymphangiomas of the small bowel mesentery in adults are rarer. We present two cases of mesenteric lymphangioma with acute abdominal pain on presentation. Case 1: A 38-year-old female presented with abdominal pain, vomiting, fever, and difficult evacuation. On abdominal examination, she had an ill-defined, tender lump, and radiological findings raised a possibility of perforation peritonitis. Thus, exploratory laparotomy was planned. Per-operatively, a mesenteric mass was found, which, on histopathological evaluation, was found to be a mesenteric lymphangioma involving the bowel. Case 2: A 27-year-old male presented with abdominal pain and difficult evacuation. Radiological evaluation revealed a multilobulated lesion involving the mesentery and with differential diagnoses of mesenteric fibromatoses and inflammatory pseudotumor. Histopathological assessment of the resected mass revealed a lymphangioma that was limited to the mesentery. Owing to their rarity and non-specific presentation, mesenteric lymphangiomas are often misdiagnosed on clinical examination and imaging. Thus, histopathological examination is the gold standard to reach a definitive diagnosis.

Early life thymectomy induces arterial dysfunction in mice

Aging of the arteries is characterized by increased large artery stiffness and impaired endothelium-dependent dilation. We have previously shown that in old (22-24 month) mice T cells accumulate within aorta and mesentery. We have also shown that pharmacologic and genetic deletion of these T cells ameliorates age-related arterial dysfunction. These data indicate that T cells contribute to arterial aging; however, it is unknown if aged T cells alone can induce arterial dysfunction in otherwise young mice. To produce an aged-like T cell phenotype, mice were thymectomized at three-weeks of age or were left with their thymus intact. At 9 months of age, thymectomized mice exhibited greater proportions of both CD4 + and CD8 + memory T cells compared to controls in the blood. Similar changes were observed in the T cells accumulating in the aorta and mesentery. We also observed greater numbers of proinflammatory cytokine producing T cells in the aorta and mesentery. The phenotypic T cell changes in the blood, aorta and mesentery of thymectomized mice were similar to those observed when we compared young (4-6 month) to old thymus intact mice. Along with these alterations, compared to controls, thymectomized mice exhibited augmented large artery stiffness and greater aortic collagen deposition as well as impaired mesenteric artery endothelium dependent dilation due to blunted nitric oxide bioavailability. These results indicate that early life thymectomy results in arterial dysfunction and suggest that an aged-like T cell phenotype alone is sufficient to induce arterial dysfunction in otherwise young mice.

Peritonectomy and resection of mesentery during Visceral-Peritoneal Debulking (VPD) in patients with stage IIIC-IV ovarian cancer: A phase I-II trial

OBJECTIVE

To describe the surgical technique, assess feasibility, efficacy, and safety of peritonectomy and/or resection of mesentery (P-Rme) during Visceral-Peritoneal Debulking (VPD) in patients with stage IIIC-IV ovarian cancer (OC).

METHODS

In April 2009 we registered a protocol study on the safety and feasibility of P-Rme. In the period April 2009-December 2022, 687 patients with FIGO stage IIIC-IV ovarian cancer underwent VPD. One hundred and twenty-nine patients (18.7%) had extensive disease on the mesentery and underwent P-Rme. Feasibility was assessed as the number of procedures completed. Efficacy was measured as the rate of Complete Resection (CR). Safety was defined by the intra- and post-operative morbidity rate specifically associated with these procedures.

RESULTS

In all patients P-Rme was successfully completed. P-me was performed in 82 patients and R-me in 47, both procedures in 23 patients. CR was achieved in all 129 patients with an efficacy of 100%. Intra-operatively 5 patients out of 129 experienced small bowel loop surgical devascularization. They required small bowel resection and anastomosis. The procedure specific morbidity was 3.8%. No post-operative complication was related to P-Rme. At 64 months median follow-up, survival outcomes in the study group were similar to patients in the control group.

CONCLUSION

Overall, almost 20% of the VPD patients needed P-Rme to obtain a CR. P-Rme was a safe and effective step during VPD. The rate of CR in the study group was 100% achieved thanks to the addition of the P-Rme. No procedure specific post-operative complications occurred but 3.8% of the patients had unplanned additional surgery related to these procedures.

Time-Lapse Observation of Cell Dynamics During Angiogenesis Using the Rat Mesentery Culture Model

The ability to track cells and their interactions with other cells during physiological processes offers a powerful tool for scientific discovery. An ex vivo model that enables real-time investigation of cell migration during angiogenesis in adult microvascular networks would enable observation of endothelial cell dynamics during capillary sprouting. Angiogenesis is defined as the growth of new blood vessels from existing ones and involves multiple cell types including endothelial cells, pericytes, and interstitial cells. The incorporation of these cell types in a physiologically relevant environment, however, represents a challenge for biomimetic model development. Recently, our laboratory has developed the rat mesentery culture model, which enables investigation of angiogenesis in an intact tissue. The objective of this chapter is to detail a protocol for tracking cellular dynamics during angiogenesis using the rat mesentery tissue culture model. The method involves harvesting mesentery tissues from adult SD-EGFP rats, culturing them in MEM + 10% fetal bovine serum, and imaging network regions over the time course of angiogenesis. In example applications, time-lapse comparison of microvascular networks in cultured tissues confirmed dramatic increases in GFP-positive capillary sprouting and GFP-positive segment density. Additionally, tracking of individual capillary sprout extensions revealed their ability to "jump" by disconnecting from one vessel segment and reconnecting to another segment in the network. GFP-positive sprouts were also capable of undergoing subsequent regression. The representative results support the use of the rat mesentery culture model for identifying and tracking cellular dynamics during angiogenesis in intact microvascular networks.

Recanalization of Portal Vein Graft Occlusion via a Percutaneous Transmesenteric Approach: A Case Report

Interventional recanalization is an effective treatment option for postoperative portal vein occlusion. A transhepatic or transsplenic approach is preferred, whereas a percutaneous transmesenteric route enables antegrade cannulation. Here, we present a case of successful percutaneous transmesenteric recanalization in a patient with a postoperative portal vein graft occlusion.

Unusual mesentery metastasis of differentiated thyroid cancer: a case report

Distant metastases of well-differentiated thyroid cancers (WDTCs) to bone and lungs are well known, while intra-abdominal, mesenteric metastases are very rare. Herein, we report a case of intra-abdominal, mesenteric metastasis of WDTC. A 62-year-old man underwent thyroid lobectomy for follicular thyroid cancer. One year later, lung metastasis was observed. The patient simultaneously underwent lung wedge resection and complete thyroidectomy. Eleven years later, serum thyroglobulin level was elevated. On the work-up study, a metastatic lesion in the lungs and a mass in the mesentery were identified. Two lesions of the lung and mesentery were surgically resected. The mass in the mesentery was pathologically diagnosed as metastatic WDTC.

Mesenteric creeping fat index defined by CT enterography is associated with early postoperative recurrence in patients with Crohn's disease

OBJECTIVES

To investigate the value of mesenteric creeping fat index (MCFI) defined by computed-tomography enterography (CTE) in patients with Crohn's Disease (CD) for predicting early postoperative recurrence.

METHODS

A total of 110 patients with CD who underwent CTE and I-stage intestinal resection surgery from December 2013 to December 2018 were enrolled. Two radiologists independently assessed CTE parameters, including MCFI, with scores ranging from 1 to 8; bowel-wall thickening, with a scale of 1 to 3; mural hyperenhancement, mural stratification, submucosal fat deposition, mesenteric fibrofatty proliferation, mesenteric hypervascularity, mesenteric fat stranding, with a scale of 0 to 2; abscess/fistula, enlarged mesenteric lymph node, abdominal and pelvic effusion, with a scale of 0 to 1. Imaging findings associated with early recurrence were assessed using logistic regression analysis.

RESULTS

Within one year follow-up, early postoperative recurrence occurred in 56.4 % (62/110) patients with CD. In univariate analysis, MCFI, bowel-wall thickening, mesenteric hypervascularity, mesenteric fat stranding, abscess/fistula and mesenteric lymphadenopathy were associated with early postoperative recurrence. Among all variables, MCFI (score ≥ 4) contributes the optimal AUC (0.838 [0.758-0.919]), specificity (89.6 %), positive predictive value (90.7 %), accuracy (83.6 %), and risk ratio (OR = 32.42 [10.69-98.33], p < 0.001). In multivariate analysis, only MCFI was an independent predictor of early postoperative recurrence (OR = 25.71 [7.65-86.35], p < 0.001).

CONCLUSION

CTE features are useful in predicting early postoperative recurrence in patients with CD, MCFI may be a valuable tool for clinical monitoring and follow-up.

Viscoelastic properties of small bowel mesentery at MR elastography in Crohn's disease: a prospective cross-sectional exploratory study

BACKGROUND

Creeping fat is a pathological feature of small bowel Crohn's disease (CD), with literature suggesting that bowel resection with extended mesenteric resection is related to less postoperative recurrences. Conventional imaging is unable to accurately quantify the disease involvement (i.e., fibrosis) of creeping fat. Quantification of disease involvement could be useful in decision-making for additional extended mesenteric resection. We investigated the feasibility of magnetic resonance elastography (MRE) of the mesentery and if MRE is capable to detect fibrotic disease involvement of mesentery in active CD.

METHODS

Multifrequency MRE yielded spatial stiffness (shear wave speed, SWS, |G*|) and fluidity maps (φ). Viscoelastic properties of seven CD patients' mesentery were compared to age- and sex-matched healthy volunteers (HV) (Mann-Whitney U-test). Within CD patients, the affected and "presumably" unaffected mesentery were compared (Wilcoxon-signed rank test). Repeatability was tested in 15 HVs (Bland-Altman analysis, coefficient of variation [CoV]). Spearman rank correlations were used to investigate the relation between microscopically scored amount of mesenteric fibrosis and viscoelastic parameters.

RESULTS

SWS, |G*|, and φ of affected mesentery in CD were higher compared to HV (p = 0.017, p = 0.001, p = 0.017). Strong correlations were found between percentage of area of mesenteric fibrosis and SWS and |G*| (p < 0.010). No differences were found within CD between affected and presumably unaffected mesentery. Repeatability of SWS showed 95% limits of agreement of (-0.09, 0.13 m/s) and within-subject CoV of 5.3%.

CONCLUSION

MRE may have the potential to measure fibrotic disease involvement of the mesentery in CD, possibly guiding clinical decision-making with respect to extended mesenteric resection.

TRIAL REGISTRATION

Dutch trial register, NL9105 , registered 7 December 2020.

RELEVANCE STATEMENT

MRE may have the potential to measure the amount of mesenteric fibrosis of the affected mesenteric fat in active Crohn's disease, giving more insight into disease progression and could potentially play a role in clinical decision-making for extended mesenteric resection.

KEY POINTS

• MRE of the mesentery in patients with active CD is feasible. • Fluidity and stiffness of the mesentery increase in active CD, while stiffness correlates with the histopathological amount of mesenteric fibrosis. • MRE provides biomarkers to quantify mesenteric disease activity in active CD.

Association of new sonographic features with outcome in neonates with necrotizing enterocolitis

BACKGROUND

We have recently noted some sonographic features in necrotizing enterocolitis that have received little or no attention in the current literature. These include thickening of the mesentery, hyperechogenicity of intraluminal intestinal contents, abnormalities of the abdominal wall, and poor definition of the intestinal wall. It has been our impression that the above four sonographic findings are generally seen in neonates with more severe necrotizing enterocolitis and may be useful in predicting outcome.

OBJECTIVES

The aim of this study is, firstly, to review a large series of neonates, known to have clinical NEC, to document how frequently the above four sonographic features occur in neonates with necrotizing enterocolitis and, secondly, to determine whether they are predictive of outcome.

MATERIALS AND METHODS

We retrospectively analyzed the clinical, radiographic, sonographic, and surgical findings in neonates with necrotizing enterocolitis between 2018 and 2021. The neonates were categorized into two groups based on outcome. Group A included neonates with a favorable outcome defined as successful medical treatment with no surgical intervention. Group B included neonates with an unfavorable outcome defined as failed medical treatment requiring surgery (for acute complications or late strictures) or death because of necrotizing enterocolitis. The sonographic examinations were reviewed with attention to the features of mesenteric thickening, hyperechogenicity of intraluminal intestinal contents, abnormalities of the abdominal wall, and poor definition of the intestinal wall. We then determined the association of these four findings with the two groups.

RESULTS

We included 102 neonates with clinical necrotizing enterocolitis: 45 in group A and 57 in group B. Neonates in group B were born at a significantly earlier gestational age (median 25 weeks, range 22-38 weeks) and had a significantly lower birth weight (median 715.5 g, range 404-3120 g) than those in group A (median age 32 weeks, range 22-39 weeks, p = 0.003; median weight 1190 g, range 480-4500 g, p = 0.002). The four sonographic features were present in both study groups but with different frequency. More importantly, all four were statistically significantly more frequently present in neonates in group B compared to group A: (i) mesenteric thickening, A = 31 (69%), B = 52 (91%), p = 0.007; (ii) hyperechogenicity of intestinal contents, A = 16 (36%), B = 41 (72%), p = 0.0005; (iii) abnormalities of the abdominal wall, A = 11 (24%), B = 35 (61%), p = 0.0004; and (iv) poor definition of the intestinal wall, A = 7 (16%), B = 25 (44%), p = 0.005. Furthermore, the proportion of neonates with more than two signs was greater in group B compared to group A (Z test, p < 0.0001, 95% CI = 0.22-0.61).

CONCLUSION

The four new sonographic features described were found to occur statistically significantly more frequently in those neonates with an unfavorable outcome (group B) than in those with a favorable outcome (group A). The presence or absence of these signs should be included in the sonographic report to convey the radiologists concern regarding the severity of the disease in every neonate, suspected or known to have necrotizing enterocolitis, as the findings may impact further medical or surgical management.

Radiologic Imaging of Traumatic Bowel and Mesenteric Injuries: A Comprehensive Up-to-Date Review

Diagnosing bowel and mesenteric trauma poses a significant challenge to radiologists. Although these injuries are relatively rare, immediate laparotomy may be indicated when they occur. Delayed diagnosis and treatment are associated with increased morbidity and mortality; therefore, timely and accurate management is essential. Additionally, employing strategies to differentiate between major injuries requiring surgical intervention and minor injuries considered manageable via non-operative management is important. Bowel and mesenteric injuries are among the most frequently overlooked injuries on trauma abdominal computed tomography (CT), with up to 40% of confirmed surgical bowel and mesenteric injuries not reported prior to operative treatment. This high percentage of falsely negative preoperative diagnoses may be due to several factors, including the relative rarity of these injuries, subtle and non-specific appearances on CT, and limited awareness of the injuries among radiologists. To improve the awareness and diagnosis of bowel and mesenteric injuries, this article provides an overview of the injuries most often encountered, imaging evaluation, CT appearances, and diagnostic pearls and pitfalls. Enhanced diagnostic imaging awareness will improve the preoperative diagnostic yield, which will save time, money, and lives.

Closed or Unclosed Mesentery? A Meta-analysis of Internal Herniation After Laparoscopic Roux-en-Y Gastric Bypass

During the laparoscopic Roux-en-Y gastric bypass procedure, closing mesentery or not was still controversial according to preexisted studies. So, the current meta-analysis aimed to compare the outcome of closure versus non-closure of mesenteric defects in laparoscopic Roux-en-Y gastric bypass. Fifteen studies were included, enrolling 53,488 patients. Based on the outcome of analysis, regarding internal hernia, Petersen space's IH, jejunal mesenteric's IH, hospital days, and reoperation, closure of the mesentery was better than non-closure. Besides, small bowel obstruction, anastomosis ulcer, stenosis, leakage, bleeding, gastrointestinal perforation, and postoperative BMI of patients show no difference between non-closure and closure.

CT-based diagnostic algorithm to identify bowel and/or mesenteric injury in patients with blunt abdominal trauma

OBJECTIVES

To develop a CT-based algorithm and evaluate its performance for the diagnosis of blunt bowel and/or mesenteric injury (BBMI) in patients with blunt abdominal trauma.

METHODS

This retrospective study included a training cohort of 79 patients (29 with BBMI and 50 patients with blunt abdominal trauma without BBMI) and a validation cohort of 37 patients (13 patients with BBMI and 24 patients with blunt abdominal trauma without BBMI). CT examinations were blindly analyzed by two independent radiologists. For each CT sign, the kappa value, sensitivity, specificity, and accuracy were calculated. A diagnostic algorithm was built using a recursive partitioning model on the training cohort, and its performances were assessed on the validation cohort.

RESULTS

CT signs with kappa value > 0.6 were extraluminal gas, hemoperitoneum, no or moderate bowel wall enhancement, and solid organ injury. CT signs yielding best accuracies in the training cohort were extraluminal gas (98%; 95% CI: 91-100), bowel wall defect (97%; 95% CI: 91-100), irregularity of mesenteric vessels (97%; 95% CI: 90-99), and mesenteric vessel extravasation (97%; 95% CI: 90-99). Using a recursive partitioning model, a decision tree algorithm including extraluminal gas and no/moderate bowel wall enhancement was built, achieving 86% sensitivity (95% CI: 74-99) and 96% specificity (95% CI: 91-100) in the training cohort and 92% sensitivity (95% CI: 78-97) and 88% specificity (95% CI: 74-100) in the validation cohort for the diagnosis of BBMI.

CONCLUSIONS

An effective diagnostic algorithm was built to identify BBMI in patients with blunt abdominal trauma using only extraluminal gas and no/moderate bowel wall enhancement on CT examination.

KEY POINTS

• A CT diagnostic algorithm that included extraluminal gas and no/moderate bowel wall enhancement was built for the diagnosis of surgical blunt bowel and/or mesenteric injury. • A decision tree combining only two reproducible CT signs has high diagnostic performance for the diagnosis of surgical blunt bowel and/or mesenteric injury.

Metastatic low-grade endometrial stromal sarcoma with variable morphologies in the ovaries and mesentery: A case report

BACKGROUND

Low-grade endometrial stromal sarcoma (LGESS) classically exhibits a proliferative morphology. However, morphological variation of extrauterine tumors presents a diagnostic challenge.

CASE SUMMARY

We report the case of a 76-year-old female patient with extensive extrauterine and abdominal neoplastic lesions. Computed tomography showed massive pleural and ascitic fluid, and there was an increase in serum cancer antigen 125. She underwent bilateral adnexectomy and tumor resection. The right ovary had been replaced by a multinodular mass that was 8.5 cm × 4.5 cm × 3.5 cm in size. In addition, there was a 24 cm × 15 cm × 13 cm mesenteric mass, which was also multinodular, with local invasion of the intestinal serosa and underlying muscle. Under the microscope, the tumors in different places exhibited two different patterns, thus presenting great challenges to diagnosis and treatment. Thorough pathological assessment eliminated all differential diagnoses in favor of metastatic LGESS derived from a 20-year-old primary tumor initially misdiagnosed as leiomyosarcoma.

CONCLUSION

LGESS morphology varies according to tumor location. Accurate diagnosis is critical for appropriate treatment and improved prognosis and patient care.

Immuno-histochemical correlation of fibrosis-related markers with the desmoplastic reaction of the mesentery in small intestine neuroendocrine neoplasms

INTRODUCTION

Small intestine neuroendocrine neoplasms (siNENs) will attain more importance due to their increasing incidence. Moreover, siNENs might lead to a desmoplastic reaction (DR) of the mesentery causing severe complications and deteriorating prognosis. The expression of fibrosis-related proteins appears to be the key mechanisms for the development of this desmoplastic reaction. Therefore, this study aimed to investigate the association of the desmoplastic mesentery with specific fibrosis-related protein expression levels.

MATERIALS AND METHODS

By immunohistochemistry, the protein expression levels of four fibrosis-related markers (APLP2, BNIP3L, CD59, DKK3) were investigated in primary tumors of 128 siNENs. The expression levels were correlated with the presence of a desmoplastic reaction and clinico-pathological parameters.

RESULTS

In the primary tumor, APLP2, BNIP3L, CD59 and DKK3 were highly expressed in 29.7% (n = 38), 64.9% (n = 83), 92.2% (n = 118) and 80.5% (n = 103), respectively. There was no significant correlation of a single marker or the complete marker panel to the manifestation of a desmoplastic mesentery. The desmoplastic mesentery was significantly associated with clinical symptoms, such as flushing and diarrhea. However, neither the fibrosis-related marker panel nor single marker expressions were associated with clinical symptoms.

DISCUSSION

The expression rates of four fibrosis-related markers in the primary tumor display a distinct pattern. However, the expression patterns are not associated with desmoplastic altered mesenteric lymph node metastases and the expression patterns did not correlate with prognosis. These findings suggest alternative mechanisms being responsible for the desmoplastic reaction.

Bowel perforation following percutaneous sclerotherapy of an intra-abdominal lymphatic malformation

Mesenteric lymphatic malformations result from abnormal proliferation of disorganized mesenteric lymphatic channels. Sclerotherapy is often preferred over surgery as it is less invasive and has lower post-procedure morbidity. Sclerotherapy has been described as durable and effective with a low complication rate. We describe a serious complication from sclerotherapy of a lymphatic malformation extending from the mesentery through the bowel wall, highlighting the spectrum of this pathology and the need for multidisciplinary management of complex cases.

The in vitro analysis of migration and polarity of blastema cells in the extracellular matrix derived from bovine mesenteric in the presence of fibronectin

Cell migration is an essential process in embryonic development, wound healing, and pathological conditions. Our knowledge of cell migration is often based on the two dimentional evaluation of cell movement, which usually differs from what occurred in vivo. In this study, we investigated cellular migration from blastema tissue toward bovine decellularized mesentery tissue. In this regard, fibronectin (FN) was assessed to confirm cell migration. Therefore, we established a cell migration model using blastema cells migration toward the extracellular matrix derived from bovine mesenteric tissue. A physiochemical decellularization method was utilized based on freeze-thaw cycles and agitation in sodium dodecyl sulfate and Triton X-100 to remove cells from the extracellular matrix (ECM) of bovine mesenteric tissue. These types of matrices were assembled by the rings of blastema tissues originated from the of New Zealand rabbits pinna and cultured in a medium containing FN in different days in vitro, and then they are histologically evaluated, and the expression of the Tenascin C gene is analyzed. By means of tissue staining and after confirmation of the cell removal from mesenteric tissue, polarity, and migration of blastema cells was observed in the interaction site with this matrix. Also, the expression of the Tenascin C gene was assessed on days 15 and 21 following the cell culture process. The results showed that the three dimentional model of cellular migration of blastema cells along with the ECM could be a suitable model for investigating cell behaviors, such as polarity and cell migration in vitro.

The role of dendritic cells in the immune niche of the peritoneum

Dendritic cells (DCs) are professional antigen presenting cells that play an important role in the induction of T cell responses. Different subsets (cDC1s, cDC2s, pDCs, and moDCs) were described based on the expression of different surface markers and functions. In the context of peritoneum, DCs are also a key population cell orchestrating immune responses against pathogens, malignant cells and tissue-damage. Furthermore, they play an important role in the promotion of an anti-inflammatory microenvironment, which is necessary to maintain tolerance and adipocyte homeostasis. The aim of this review is to summarize the current knowledge of the functional and phenotypic features of peritoneal DCs and shed some light on the importance of these cells within this unique cavity and its associated components: the omentum, the mesentery and gut-associated lymphoid tissue (GALT).

Prevalence and significance of mesentery thickening and lymph nodes enlargement in Crohn's disease

BACKGROUND

Mesentery thickening and enlarged lymphnodes are typical findings of Crohn's disease (CD), but their role is unknown. Aim of the present study was to evaluate their prevalence and significance on postoperative complications and long-term surgical recurrence after CD surgery.

METHODS

1272 consecutive, unselected patients were retrospectively reviewed, divided into 4 groups based on the presence or absence of a thickened mesentery and enlarged lymphnodes, and stratified for primary or recurrent surgical procedure. In all patients but those treated with strictureplasty the mesentery and lymphnodes were removed. Patients' characteristics, peri-operative findings, and long-term recurrence were compared by univariate and multivariate analysis.

RESULTS

Thickened mesentery and enlarged lymphnodes were not present in all cases, were typical of ileal location and penetrating behaviour, had a constant decrease over recurrences, were independent of either pre-operative medical therapy or surgical approach, did not increase the duration of surgery and complications, presented similar 20-years recurrence rate to normal mesentery and lymphnodes. Lymphopathy was associated to a worst nutritional status during disease recurrences. At multivariate analysis, age, location, and behaviour, but not mesenteric characteristics, were related to an increased risk of surgical recurrence.

CONCLUSIONS

This study provides new information on mesentery and lymphnodes in CD patients. Further studies are needed to clarify the appropriate surgical approach.

An Ex Vivo Tissue Culture Method for Discovering Cell Dynamics Involved in Stromal Vascular Fraction Vasculogenesis Using the Mouse Mesentery

Stromal vascular fraction (SVF), isolated from adipose tissue, identifies as a rich cell source comprised of endothelial cells, endothelial progenitor cells, pericytes, smooth muscle cells, fibroblasts, and immune cells. SVF represents a promising therapeutic heterogonous cell source for growing new blood microvessels due to its rich niche of cells. However, the spatiotemporal dynamics of SVF within living tissues remain largely unknown. The objective of this chapter is to describe a protocol for culturing SVF on mouse mesentery tissues in order to aid in the discovery of SVF dynamics and associated vessel growth over time. SVF was isolated from the inguinal adipose from adult mice and seeded onto mesentery tissues. Tissues were then cultured for up to 5 days and labeled with endothelial cell and pericyte markers. Representative results demonstrate the observation of SVF-derived vasculogenesis characterized by de novo vessel formation and subsequent vessel connection.

Para-aortic nodal metastasis of mesenteric perivascular epithelioid cell tumor (PEComa)

Perivascular epithelioid cell tumors (PEComas) are a group of tumours of mesenchymal origin having a characteristic pathological presence of the epitheloid cell around blood vessels. They are uncommon tumours and hence their exact etiology and pathogenesis remain unclear. They can occur at any part of the body but the common sites of involvement are the gastrointestinal system and the genitourinary system. The isolated involvement of the intestinal mesentery is very rare, with only a few cases reported in the literature till date. The involvement of lymph nodes by these tumours is exceptionally rare. We report a hitherto undescribed case of mesenteric PEComa in a young female who developed para-aortic nodal metastasis.

Safety and efficacy of emergency transarterial embolization for mesenteric bleeding

Background

Patients with spontaneous or traumatic active mesenteric bleeding cannot be treated endoscopically. Transarterial embolization can serve as a potential alternative to emergency surgery. Literature on transarterial embolization for mesenteric bleeding remains very scarce. The objective of this study was to evaluate the safety and efficacy of transarterial embolization for mesenteric bleeding. We reviewed all consecutive patients admitted for mesenteric bleeding to the interventional radiology department, in a tertiary center, between January 2010 and March 2021. Mesenteric bleeding was defined as mesenteric hematoma and contrast extravasation and/or pseudoaneurysm visible on pre-operative CT scan. We evaluated technical success, clinical success, and complications.

Results

Among the 17 patients admitted to the interventional department for mesenteric bleeding, 15 presented with active mesenteric bleeding requiring transarterial embolization with five patients with hemodynamic instability. Mean age was 67 ± 14 years, including 12 (70.6%) males. Technical success was achieved in 14/15 (93.3%) patients. One patient with technical failure was treated by percutaneous embolization with NBCA-Lipiodol mixture. Three patients (20%) had early rebleeding: two were treated by successful repeat embolization and one by surgery. One patient (6.7%) had early death within 30 days and two patients (13.3%) had late death after 30 days. Mean length of hospitalization was 12.8 ± 7 days. There were no transarterial embolization-related ischemic complications.

Conclusion

Transarterial embolization is a safe and effective technique for treating mesenteric bleeding even in patients with hemodynamic instability. Transarterial embolization doesn’t close the door to surgery and could be proposed as first intention in case of mesenteric bleeding.

Malignant Peripheral Nerve Sheath Tumor Arising from Small Bowel Mesentery: an Extremely Rare Case with Review of Literature

PURPOSE

Malignant peripheral nerve sheath tumor (MPNST) of small bowel mesentery is a rare tumor. We report a rare case of MPNST of small bowel mesentery in a patient without neurofibromatosis (NF).

METHODS

A 50-year-old male, with no features suggestive of NF1, presented to us with complaints of pain abdomen. Contrast-enhanced computed tomography (CECT) of the abdomen revealed a mass in the infrarenal region. On laparotomy, mass was seen to be arising from the mesentery of the jejunum. En-bloc resection of the tumor was done, and histopathological examination was suggestive of malignant peripheral nerve sheath tumor of the small bowel mesentery.

RESULT

Patient received adjuvant external beam radiotherapy to a dose of 50.4 Gy to the tumor bed. The patient was planned for chemotherapy but absconded and later came with recurrence. The patient finally succumbed to disease.

CONCLUSION

Surgery is the mainstay of treatment. Adjuvant treatment should be based on histopathological report.

Extensive abdominal lymphangiomatosis involving the small bowel mesentery: A case report

BACKGROUND

Abdominal lymphangiomatosis is a rare benign condition accounting for less than 1% of all the cases of lymphangiomatosis. Management usually involves radical surgical excision; however, depending upon the extent of involvement, patient condition, and absence of complications, conservative management can be also considered.

CASE SUMMARY

We present the case of a 32-year-old male who presented with short onset abdominal pain and melena. Physical examination findings were within normal limits, except for left lower abdominal tenderness. Upper gastrointestinal endoscopy was within normal limits. Abdominal and pelvic ultrasound and computed tomography (CT) scan revealed numerous, variably-sized cystic lesions within the abdominal cavity, exclusively and extensively affecting the small bowel mesentery with sparing of the retroperitoneum. The diagnosis was confirmed by CT and cytological examination. Radical surgical excision was technically impossible in this patient because of the extensive involvement of the mesentery; therefore, the patient was managed conservatively.

CONCLUSION

Extensive and exclusive small bowel mesentery involvement in abdominal lymphangiomatosis is rare. Imaging modalities play an important role in establishing the diagnosis and conservative management can be considered when surgery is technically impossible.

Ultrasound and contrast enhanced CT imaging of a colon mesentery leiomyosarcoma

•

Primary mesenteric leiomyosarcoma is a very rare, aggressive neoplasm.

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Tumour recurrence and metastatic spread is a significant risk following surgical treatment.

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Follow-up is warranted and likely improves patient survival rates.

Primary leiomyosarcoma of the colon mesentery is an extremely rare neoplasm, and only a small number of cases have been reported. We describe a case of leiomyosarcoma originating in the colonic mesentery, in a 68-year-old woman. Ultrasound showed a heterogeneous mass with varying vascularization in the left fossa. Central areas of the mass were hypoechoic, without detectable vascularization. Contrast enhanced computed tomography (CECT) of chest and abdomen showed a contrast enhanced tumour, with central non-enhanced areas. The tumour was radically resected and histopathology showed primary leiomyosarcoma. Two years after primary surgery, follow-up CECT revealed a local recurrence, which was re-resected. Subsequent follow-up CECT since have shown no sign of recurrence.

[Mesenteric arterial ischemia: from diagnosis to decision]

FROM DIAGNOSIS TO MULTIDISCIPLINARY TREATMENT IN INTESTINAL STOKE UNIT Acute mesenteric ischemia (AMI) is a severe vascular and intestinal emergency, most commonly related to the occlusion (mesenteric occlusive disease or emboli) of the superior mesenteric artery (SMA). Such as myocardial infarction or stroke, SMA occlusion is responsible of an intestinal infarction. In case of an early revascularization of the SMA, AMI can be reversible with no need for bowel resection. However, when left untreated, AMI fatally leads to irreversible intestinal necrosis and death following multiple organ failure. Considering its poor prognosis, AMI might be systematically suspected in case of a sudden, unusual and intense abdominal pain. Because AMI has a nonspecific clinical presentation, delayed diagnosis are frequent and unfortunately associated with poor outcomes. Therefore, general and emergency doctors, along with gastroenterologists, have a key role to play in the recognition of early AMI. In any case of clinically suspected AMI, an abdominal computed tomography angiogram might be urgently performed. Chronic mesenteric ischemia can also be revealed by postprandial abdominal pain associated with food fear and weight loss. In recent years, there has been a major improvement in the treatment of AMI following the creation of a French intestinal stroke center, gathering the expertise of specialized gastroentorologists, vascular and digestive surgeons, radiologists and intensivists. A multimodal and multidisciplinary approach combining the use of a systematic medical protocol, early revascularization of viable bowel and resection of non viable bowel when needed, has dramatically improved the prognosis of AMI, with current survival rates of 80 % and bowel resection being avoided in nearly two thirds of patients.

Significant blunt bowel and mesenteric injury - Comparison of two CT scoring systems in a trauma registry cohort

PURPOSE

This study evaluated and compared two imaging-based scoring systems for the detection of significant blunt bowel and mesenteric injury (sBBMI) by emergency computed tomography (CT).

METHODS AND MATERIALS

We included all consecutive adult polytrauma patients admitted to our emergency department following a road traffic accident from January 2008 to June 2015, provided that intravenously contrast-enhanced whole-body CT examination was performed immediately after hospital admission. Two radiologists, blinded to patients' outcome, reviewed the CT examinations for distinctive direct intestinal or mesenteric vascular injury and indirect signs of abdominal injury. These findings were correlated with the patients' surgical or interventional radiology findings, autopsy, or clinical follow-up (>24 h). Two previously validated imaging-based bowel-injury scoring systems, the CT-based Faget score and the clinically and radiologically based Mc Nutt score (BIPS), were compared by applying each to our trauma cohort. Student t-test, chi-squared, and logistic regression were used in analyses.

RESULTS

Twenty-one of 752 analysed patients (2.8 %) had confirmed sBBMI. Active mesenteric bleeding, mesenteric and free pneumoperitoneum, small haemoperitoneum, non-focal bowel wall thickening, mesenteric/pericolic fat stranding, and anterior abdominal wall injury were significantly correlated with sBBMI, as did the two evaluated scoring systems (p < 0.001). However, multivariate logistic regression revealed the superiority of the Faget score to the McNutt score.

CONCLUSION

The prevalence of sBBMI among polytrauma patients is low. Early diagnosis is necessary to avoid increased mortality. Certain CT features are pathognomic of sBBMI and must not be overlooked. Scoring systems are helpful, especially when they are based on radiological signs.

Primary extraskeletal osteosarcoma of sigmoid mesocolon: a case report and a review of the literature

Background

Extraskeletal osteosarcoma (ESOS) is a rare mesenchymal malignancy, which produces osteoid, bone, or chondroid material and is located in the soft tissue without attachment to skeletal bones and periosteum. One of the things that ESOS originated from mesentery is much rarer.

Case presentation

A 75-year female had a history of pain in the left lower abdomen for more than 4 months. Abdominal computerized tomography (CT) and magnetic resonance imaging revealed a large, irregular, and solid-cystic mass (largest diameter was 11.5 cm). The tumor was radically removed during an open operation. It was composed of abundant osteoid and polyhedral-shaped tumor cells with high atypia and high mitotic activity microscopically. The final pathological diagnosis was osteoblastic osteosarcoma, arising from the sigmoid mesocolon with negative margins. A 9-month follow-up by CT exhibited signs of peritoneal metastasis.

Conclusions

Given the rarity of cases of mesenteric ESOS, diagnosis mainly depended on pathology findings or should be taken into consideration when the mesenteric mass was found. Its most effective treatment had not been determined, with surgical excision being generally accepted. Ensuring negative surgical margins may be an important factor affecting prognosis.

Features of CT and EUS in mesenteric plexiform neurofibroma with Neurofibromatosis type I: A case report

Plexiform neurofibroma(PNF) is a rare benign tumor of the peripheral nerve, belonging to a subtype of neurofibroma. PNF is common in the head, neck and trunk. It is uncommonly observed in the mesentery. We report a case of mesenteric PNF in a 64-year-old man history of neurofibromatosis type I(NF1), which caused abdomen pain. In addition, the computer tomography(CT) and endoscopic ultrasonography(EUS) manifestations of mesenteric PNF were analyzed. The imaging appearance of a mesenteric plexiform neurofibroma is that many low-density (CT) /mixed echo (EUS) soft tissue masses surrounding the superior mesenteric artery, but not surrounding the superior mesenteric vein. Our case adds to the limited literature regarding NF1 presenting with mesenteric PNF. The computer tomography and endoscopic ultrasonography may facilitate confirma diagnosis of mesenteric PNF.

[Motility disorder and weight loss in a 71-year-old male patient]

A 71-year-old man presented to this clinic for evaluation of an unclear abdominal tumor. He complained of abdominal pain, weight loss and motility disorders, which began some weeks previously. Ultrasound and computed tomography (CT) scans showed a large mesenterial space-occupying lesion with accompanying lymphadenopathy, slight accumulation of ascites and venous congestion. For confirmation of the suspected diagnosis of a sclerosing mesenteritis and exclusion of a lymphoma a laparoscopy was carried out with excision of tissue. The material was not adequately representative so that a laparotomy was carried out for removal of a new tissue specimen. The tissue specimen confirmed the rare diagnosis of sclerosing mesenteritis and due to the complaints a pharmaceutical treatment with prednisone and tamoxifen was initiated.

[Exploration of the theoretical system of membrane anatomy in colorectal surgery]

Despite the concept of membrane anatomy has been widely used in minimally invasive colorectal surgery, the definition of membrane anatomy and the establishment of membrane plane remain controversial. Therefore, it is difficult to establish a unified theoretical system of membrane anatomy. Through embryological studies and anatomical findings on the integrity and continuity of membranes, we try to discuss the theoretical system of membrane anatomy in colorectal surgery from three aspects: membrane anatomical system, membrane anatomical elements and membrane anatomical mechanism. The establishment of a unified theoretical system of membrane anatomy will not only contribute to the standardization operative procedures, but also to the establishment of uniform surgical standards for colorectal cancer.

CT, MRI, and FDG-PET imaging findings of low-grade extrauterine endometrial stromal sarcoma arising from the mesentery: A case report

Endometrial stromal sarcoma is a rare uterine mesenchymal neoplasm, and extrauterine endometrial stromal sarcoma is even rarer, with a limited number of case reports. In the present report, we present a case of low-grade extrauterine endometrial stromal sarcoma originating from the mesentery in a 49-year-old woman, without endometrial stromal sarcoma in the uterus or evidence of endometriosis. The tumor was diagnosed using recombination of the JAZF1 gene by fluorescence in situ hybridization. Computed tomography, magnetic resonance imaging, and 18F-fluorodeoxyglucose positron emission tomography/computed tomography showed a 13 cm, primarily polycystic, mass containing a contrast-enhancing solid component with restricted diffusion and mild 18F-fluorodeoxyglucose uptake. A large cystic component may be a characteristic feature of extrauterine endometrial stromal sarcoma, given the low pressure from the surrounding tissues.

Intra-abdominal EWSR1/FUS-CREM-rearranged malignant epithelioid neoplasms: two cases of an emerging aggressive entity with emphasis on misleading immunophenotype

CREB family (CREB1, ATF1, and CREM) gene fusions are defining markers in diverse mesenchymal neoplasms (clear cell sarcoma, angiomatoid fibrous histiocytoma, and others). However, neoplasms harboring EWSR1-CREM/FUS-CREM fusions are rare and poorly characterized. We describe two cases (55-year-old male with 7.5 cm renal mass and 32-year-old female with 5.5 cm mesenteric mass) illustrating their misleading immunophenotypes. Histologically, both showed eosinophilic and focally clear epithelioid cells arranged into sheets, nests, and trabeculae. Immunohistochemistry showed ALK, EMA, and AE1/AE3 immunoreactivity suggesting ALK-rearranged renal cell carcinoma (Case 1) and coexpression of keratin, EMA, synaptophysin, and chromogranin-A, suggesting neuroendocrine neoplasm (Case 2). Targeted RNA sequencing revealed EWSR1-CREM (Case 1) and FUS-CREM (Case 2) fusions. These cases add to the spectrum of CREM fusion-positive intra-abdominal epithelioid neoplasms. Their unusual immunophenotype and unexpected sites represent major pitfalls, underline a wide differential diagnosis, and emphasize the value of molecular testing in correctly diagnosing them.

Unusual Sites of Necrotic Collections in Acute Necrotizing Pancreatitis: Association with Parenchymal Necrosis and Clinical Outcomes

BACKGROUND

The presence of necrotic collection in acute necrotizing pancreatitis (ANP) at intra-abdominal sites other than the retroperitoneum has not been systematically studied.

AIM

To investigate unusual sites of necrotic collections at computed tomography (CT) and to evaluate association with pancreatic necrosis and clinical outcomes.

METHODS

This retrospective study comprised of consecutive patients with ANP evaluated between January 2018 and March 2019. Based on CT findings, patients were divided into two groups: collections at unusual sites (small bowel mesentery, mesocolon, omentum, subcapsular collections along liver and spleen, pelvis, anterior abdominal wall, and inguinoscrotal regions) and collections at usual retroperitoneal locations (lesser sac, gastrosplenic location, anterior and posterior pararenal spaces, and paracolic gutters). The differences in CT findings and clinical outcomes (need for drainage, length of hospitalization, intensive care unit admission, surgery, and death) between the two groups were evaluated.

RESULTS

A total of 75 patients with ANP were evaluated. There were 25 (33.3%) patients with collections in unusual locations. These included mesentery (n = 17), splenic subcapsular location (n = 7), omentum (n = 6), hepatic subcapsular location (n = 4), anterior abdominal wall (n = 3), pelvis (n = 2), and inguinoscrotal location (n = 1). Compared to patients with collections at usual locations (n = 50), there were no differences in the CT findings except complete parenchymal necrosis (32% vs. 0%, P = .001). There were no statistically significant differences in the clinical outcomes between the two groups.

CONCLUSIONS

Mesenteric collections are frequent in ANP. The other non-retroperitoneal sites are infrequently involved. There is no association between unusual sites of collection and clinical outcomes.

Epithelioid inflammatory myofibroblastic sarcoma: the youngest case reported

Epithelioid inflammatory myofibroblastic sarcoma (EIMS) is a rare variant of the inflammatory myofibroblastic tumor. It has an aggressive clinical course and a high rate of recurrence. EIMS primarily affects children and young adults. Hereby, we report this entity in a 4-month-old infant who presented with an abdominal mass. Imaging studies revealed a large hypodense mesentery-based lesion involving the right half and mid-region of the abdomen. The mass with an attached segment of the small bowel was excised in toto. Grossly, a large encapsulated tumor was identified arising from the mesentery of the small bowel. The histological examination showed a tumor consisting of epithelioid to spindle cells loosely arranged in a myxoid background with numerous blood vessels and lymphoplasmacytic inflammatory infiltrate. On immunohistochemistry, the tumor cells showed positivity for ALK1 (nuclear), desmin, SMA, CD68, and focal positivity for CD30. A final diagnosis of EIMS of the small intestine was rendered. To the best of our knowledge, this case is the youngest reported case in literature.

Immunoglobulin G4-related systemic disease: mesenteric and peritoneal involvement with radiopathological correlation and differential diagnoses

Since its first introduction in 2003 by Kamisawa et al., IgG4-related disease has gained wide interest in the imaging community, and several manuscripts have been published regarding its imaging features. In addition to initial observations in the pancreaticobiliary system, it is now well known that the disease may involve every organ system in the body. There is not much information in the imaging literature about the involvement of mesentery, omentum, and peritoneum in this disease. This article aims to provide more information about the imaging findings of IgG4-related disease regarding these areas by making radiopathological correlations and discussing the possible differential diagnoses.

Incidental mesonephric remnant hyperplasia of the jejunal mesentery: A diagnostic challenge

Mesonephric remnants are embryonic vestiges of the mesonephric (Wolffian) ducts which regress during normal development. These remnants have been uncommonly reported in the female and male reproductive tract as a spectrum of morphologic lesions that can be misdiagnosed as carcinoma. One case of mesonephric remnant hyperplasia of the jejunal mesentery incidentally found in a 47-year-old man is herein reported. This is the first description of mesonephric hyperplasia arisen in the mesentery. The presence of ducts, tubules, and cysts lined by bland, epithelial, cuboidal cells with scant cytoplasm, and diffuse pseudoinfiltrative growth pattern can raise the possibility of neoplasia. Immunohistochemically, mesonephric epithelia have a characteristic staining. CD10 highlights the apical-luminal aspect of the cells. Besides, intense reactivity is showed for high-molecular-weight cytokeratin (CK), CK7, bcl2, and vimentin. The main differential diagnosis includes mesothelial hyperplasia, epithelial mesothelioma, well-differentiated neuroendocrine tumor, and infiltration due to acinar adenocarcinoma of the prostate. However, a detailed microscopic study with the aid of immunohistochemistry helps separate mesonephric remnants from malignant processes. The mesonephric hyperplasia of the mesentery we have reported adds to the spectrum of mesonephric remnants a new location. Familiarity with this lesion is indispensable to avoid overdiagnosis.

[Intraoperative anatomical observation of mesentery morphology of colonic splenic flexure]

Objective: At present, surgeons do not know enough about the mesenteric morphology of the colonic splenic flexure, resulting in many problems in the complete mesenteric resection of cancer around the splenic flexure. In this study, the morphology of the mesentery during the mobilization of the colonic splenic flexure was continuously observed in vivo, and from the embryological point of view, the unique mesenteric morphology of the colonic splenic flexure was reconstructed in three dimensions to help surgeons further understand the mesangial structure of the region. Methods: A total of 9 patients with left colon cancer who underwent laparoscopic radical resection with splenic flexure mobilization by the same group of surgeons in Union Hospital of Fujian Medical University from January 2018 to June 2019 were enrolled. The splenic flexure was mobilized using a "three-way approach" strategy based on a middle-lateral approach. During the process of splenic flexure mobilization, the morphology of the transverse mesocolon and descending mesocolon were observed and reconstructed from the embryological point of view. The lower margin of the pancreas was set as the axis, and 4 pictures for each patient (section 1-section 4) were taken during middle-lateral mobilization. Results: The median operation time of the splenic flexure mobilization procedure was 31 (12-55) minutes, and the median bleeding volume was 5 (2-30) ml. One patient suffered from lower splenic vessel injury during the operation and the bleeding was stopped successfully after hemostasis with an ultrasound scalpel. The transverse mesocolon root was observed in all 9 (100%) patients, locating under pancreas, whose inner side was more obvious and tough, and the structure gradually disappeared in the tail of the pancreatic body, replaced by smooth inter-transitional mesocolon and dorsal lobes of the descending colon. The mesenteric morphology of the splenic flexure was reconstructed by intraoperative observation. The transverse mesocolon was continuous with a fan-shaped descending mesocolon. During the embryonic stage, the medial part (section 1-section 2) of the transverse mesocolon and the descending mesocolon were pulled and folded by the superior mesenteric artery (SMA). Then, the transverse mesocolon root was formed by compression of the pancreas on the folding area of the transverse mesocolon and the descending mesocolon. The lateral side of the transverse mesocolon root (section 3-section 4) was distant from the mechanical traction of the SMA, and the corresponding folding area was not compressed by the tail of the pancreas. The posterior mesangial lobe of the transverse mesocolon and the descending mesocolon were continuous with each other, forming a smooth lobe. This smooth lobe laid flat on the corresponding membrane bed composed of the tail of pancreas, Gerota's fascia and inferior pole of the spleen. Conclusions: From an embryological point of view, this study reconstructs the mesenteric morphology of the splenic flexure and proposes a transverse mesocolon root structure that can be observed consistently intraopertively. Cutting the transverse mesocolon root at the level of Gerota's fascia can ensure the complete resection of the mesentery of the transverse colon.

Severe COVID-19 initially presenting as mesenteric adenopathy

Coronavirus disease 2019 (COVID-19) can present with abdominal pain in children and adults. Most imaging findings have been limited to characteristic lung findings, as well as one report of bowel-ischemia-related findings in adults. We report a case of COVID-19 in a healthy teenager who initially presented with isolated mesenteric adenopathy, typically a self-limited illness, which progressed to severe illness requiring intensive care before complete recovery. The boy tested negative for COVID-19 twice by polymerase chain reaction (PCR) from upper respiratory swabs before sputum PCR resulted positive. A high index of suspicion should be maintained for COVID-19 given the continued emergence of new manifestations of the disease.

Comparison of Adrenergic and Purinergic Receptor Contributions to Vasomotor Responses in Mesenteric Arteries of C57BL/6J Mice and Wistar Rats

INTRODUCTION

The sympathetic nervous system can modulate arteriolar tone through release of adenosine triphosphate and norepinephrine, which bind to purinergic and adrenergic receptors (ARs), respectively. The expression pattern of these receptors, as well as the composition of neurotransmitters released from perivascular nerves (PVNs), can vary both in organ systems within and across species, such as mice and rats.

OBJECTIVE

This study explores the function of α1A subtypes in mouse and rat third-order mesenteric arteries and investigates PVN-mediated vasoconstriction to identify which neurotransmitters are released from sympathetic PVNs.

METHODS

Third-order mesenteric arteries from male C57BL/6J mice and Wistar rats were isolated and mounted on a wire myograph for functional assessment. Arteries were exposed to phenylephrine (PE) and then incubated with either α1A antagonist RS100329 (RS) or α1D antagonist BMY7378, before reexposure to PE. Electrical field stimulation was performed by passing current through platinum electrodes positioned adjacent to arteries in the absence and presence of a nonspecific alpha AR blocker phentolamine and/or P2X1-specific purinergic receptor blocker NF449.

RESULTS

Inhibition of α1 ARs by RS revealed that PE-induced vasoconstriction is primarily mediated through α1A and that the contribution of the α1A AR is greater in rats than in mice. In the mouse model, sympathetic nerve-mediated vasoconstriction is mediated by both ARs and purinergic receptors, whereas in rats, vasoconstriction appeared to only be mediated by ARs and a nonpurinergic neurotransmitter. Further, neither model demonstrated that α1D ARs play a significant role in PE-mediated vasoconstriction.

CONCLUSIONS

The mesenteric arteries of male C57BL/6J mice and Wistar rats have subtle differences in the signaling mechanisms used to mediate vasoconstriction. As signaling pathways in humans under physiological and pathophysiological conditions become better defined, the current study may inform animal model selection for preclinical studies.

Usefulness of 18F-fluorodeoxyglucose-positron emission tomography/computed tomography in primary cystadenocarcinoma of the mesentery: a case report

BACKGROUND

Mesenteric cysts have various histological forms, including mesenteric cystadenomas and borderline cystic neoplasms. Primary cystadenocarcinoma of the mesentery is extremely rare; therefore, the clinical and radiological features of this tumor have not been fully elucidated.

CASE PRESENTATION

A 50-year-old Japanese woman had a complaint of a left-sided abdominal distention. Enhanced computed tomography and magnetic resonance imaging revealed a unilocular cystic lesion measuring approximately 10 cm located in the left side of the abdomen. ¹⁸F-fluorodeoxyglucose (FDG)-positron emission tomography/computed tomography (PET/CT) revealed mottled mild FDG uptake in the cyst wall and intense FDG uptake in several mural nodules. The cystic mass with the descending colon was completely removed. Pathological examination of the specimens revealed various histologic patterns of adenocarcinoma, including mucin production in the mural nodules. We eventually diagnosed a primary cystadenocarcinoma arising from the mesentery of the descending colon.

CONCLUSIONS

Malignancy should be suspected in mesenteric or retroperitoneal cystic tumors with high FDG uptake, and complete resection should be performed with adequate margins.

Primary extra-gastrointestinal stromal tumor (EGIST) of the mesentery: Case report and review of literature

Introduction

Gastrointestinal stromal tumors (GISTs) represent <1% of all gastrointestinal (GI) tumors. Extra-gastrointestinal stromal tumors (EGISTs) are mesenchymal tissue neoplasm arising outside the GI tract. This rare group comprises only 5% of all GISTs. This case demonstrates a rare entity in a patient with non-specific symptoms, a large tumor size and unremarkable past personal and family history.

Presentation of case

We present a 45-year old man with non-specific symptoms who was diagnosed with a primary EGIST arising in the small bowel mesentery after surgery. The tumor was not compromising the GI tract and it was completely resected. The tumor was sent for pathological examination that confirmed the diagnosis. Histological examination revealed a 15 cm in diameter mass, comprised of spindle cells and high mitotic activity. Treatment with imatinib mesylate was initiated.

Discussion

There have been only a few previous reports of EGISTs arising from the small bowel mesentery. It is believed that EGISTs originate from cells with similar pathological characteristics and biological behaviour as the intestinal cells of Cajal. Such tumors are associated with poorer prognosis, lager tumor size and younger presentation than their GI counterparts. The preferred treatment is complete surgical resection. The addition of specific tyrosine kinase inhibitors such as imatinib mesylate is recommended for high risk patients. Even though morphological and immunohistochemical similarities between GISTs and EGISTs are described, their pathogenesis, incidence, genetic background, complications and prognosis are not completely known because they are extremely rare.

Conclusion

EGISTs are very rare tumors which originate from cells outside the GI tract and are associated with a more aggressive biological behavior than their GI counterparts. These tumors may grow without any clinical implications and should be kept in mind in the differential diagnosis for patients presenting with an abdominal mass. Further studies are needed due to lack of large patient cohort studies and long-term follow-up regarding the prognosis and management of this rare pathology.

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EGISTs are extremely rare. They represent only 5% of all GISTs, which comprises only <0.05% of all GI tumors.

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High index of suspicion in patients with nonspecific symptoms and the presence of an abdominal mass is necessary.

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The preferred treatment is a complete surgical resection in low-risk patients.

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Clinicopathologic parameters and clinical implications are not yet described in literature.