Anatomy of the lymphatics

The right lymphatic duct: basic anatomy and clinical relevance

The anatomical variability of the thoracic duct and the right lymphatic duct predisposes them to inadvertent damage following head and neck surgery thereby leading to chyle leak which is an uncommon complication with potentially significant associated morbidity. Although chyle leak is predominately associated with left-sided neck surgery, it also occurs as a complication of the right-sided neck dissection. Variable figures concerning chyle leakage after right-sided neck dissections were reported, ranging from 0 per cent to higher prevalences such as 14%, 24%, 33% and 60% of total cases of chyle leakages associated with neck surgery. The right-sided complications may implicate the right lymphatic duct and right-sided terminations of the thoracic duct into the venous system which occur in about 1-6% of humans. Other clinically relevant conditions involving the right-sided major lymphatic vessels include chyle leaks following right anterior cervical spine surgery, cysts of the right lymphatic duct and dilatation of the right lymphatic duct in the setting of recurrent cervical swelling. This article presents a review of the literature concerning the basic anatomy and the clinical relevance of the right lymphatic duct and the right-sided terminations of the thoracic duct into the venous circulation.

Lymphatic Imaging and Intervention in Congenital Heart Disease

The lymphatic system plays a central role in some of the most devastating complications associated with congenital heart defects. Diseases like protein-losing enteropathy, plastic bronchitis, postoperative chylothorax, and chylous ascites are now proven to be lymphatic in origin. Novel imaging modalities, most notably, noncontrast magnetic resonance lymphangiography and dynamic contrast-enhanced magnetic resonance lymphangiography, can now depict lymphatic anatomy and function in all major lymphatic compartments and are essential for modern therapy planning. Based on the new pathophysiologic understanding of lymphatic flow disorders, innovative minimally invasive procedures have been invented during the last few years with promising results. Abnormal lymphatic flow can now be redirected with catheter-based interventions like thoracic duct embolization, selective lymphatic duct embolization, and liver lymphatic embolization. Lymphatic drainage can be improved through surgical or interventional techniques such as thoracic duct decompression or lympho-venous anastomosis.

Dosimetric Effect of Thymus and Thoracic Duct on Radiation-Induced Lymphopenia in Patients With Primary Lung Cancer Who Received Thoracic Radiation

Purpose

Radiation-induced lymphopenia is a well-recognized factor for tumor control and survival in patients with cancer. This study aimed to determine the role of radiation dose to the thymus and thoracic duct on radiation-induced lymphopenia.

Methods and Materials

Patients with primary lung cancer treated with thoracic radiation therapy between May 2015 and February 2020 with whole blood count data were eligible. Clinical characteristics, including age, gender, histology, stage, chemotherapy regimen, radiation dosimetry, and absolute lymphocyte count (ALC) were collected. The thymus and thoracic duct were contoured by one investigator for consistency and checked by one senior physician. The primary endpoint was radiation-induced decrease in lymphocytes, defined as the difference in ALC (DALC) before and after radiation therapy.

Results

The data of a total of 116 consecutive patients were retrospectively retrieved. Significant correlations were found between DALC and several clinical factors. These factors include stage, chemotherapy or concurrent chemoradiation, biologically effective dose (BED), mean lung dose, mean body dose, effective dose to immune cells (EDIC), mean thymus dose (MTD), and mean thoracic duct dose (MTDD) (all P < .05). Ridge regression showed that DALC = 0.0063 × BED + 0.0172 × EDIC + 0.0002 × MTD + 0.0147 × MTDD + 0.2510 (overall P = .00025 and F = 5.85). The combination model has the highest area under the curve of 0.77 (P < .001) when fitting the logistic regression model on DALC categorized as binary endpoint. The sensitivity and specificity of the combined model were 89% and 58%, respectively.

Conclusions

This study demonstrated for the first time that radiation doses to the thymus and thoracic duct are strongly associated with radiation-induced lymphopenia patients with lung cancer. Further validation studies are needed to implement thymus and thoracic duct as organs at risk.

Inguinal intranodal lymphangiography reveals a high incidence of suprainguinal lymphatic disease in patients with leg edema undergoing stenting for symptomatic chronic iliofemoral venous obstruction

OBJECTIVE

Recent studies have emphasized the important role lymphatics play in the drainage of interstitial fluid and edema prevention. Although the infrainguinal lymphatics have been studied in some depth, with patterns of pathology identified, such data above the groin are sparse, especially for patients with phlebolymphedema. The present study attempts to evaluate the status of lymphatic flow above the inguinal ligament in patients presenting with edema and undergoing stenting for symptomatic chronic iliofemoral venous obstruction (CIVO).

METHODS

A total of 31 lower limbs that underwent pedal lymphoscintigraphy for leg edema and subsequent stenting for symptomatic CIVO formed the study cohort. Each limb underwent intranodal lymphangiography of an ipsilateral inferior inguinal lymph node (10 mL of lipiodol) at the time of stenting. Fluoroscopic visualization of lipiodol transit was performed at 20, 40, and 60 minutes and 3 hours after injection. Enumeration of the lymph nodes and lymphatic collector vessels from above the inguinal ligament to L1, visualization of the thoracic duct, the time delay to visualization of the thoracic duct, and pathologic changes to the thoracic duct when present were all evaluated. These anomalies were independently scored, with the scores combined to generate a total suprainguinal score (range, 0-3). This score was then compared to the limb's lymphoscintigraphically derived infrainguinal score (total infrainguinal score range, 0-3) using the t test and Spearman correlation. The clinical outcomes (grade of swelling, venous clinical severity score) after stenting were appraised.

RESULTS

Of the 30 patients (31 limbs), 18 were women, with left laterality noted in 23 limbs. A nonthrombotic iliac vein lesion occurred in 9 limbs and post-thrombotic syndrome in 22 limbs. Of the 31 limbs, 24 (77%) had suprainguinal lymphatic disease (SLD), with 22 of the 24 limbs having severe SLD and 2, mild SLD. When SLD was compared with infrainguinal lymphatic disease, 6 limbs (19%) had the same degree of involvement above and below the groin (1 with normal and 5 with severe disease), 17 limbs (55%) had more severe SLD, and 8 limbs (26%) had more severe infrainguinal lymphatic disease. Three limbs with normal pedal lymphoscintigraphic findings had severe SLD. The Spearman correlation coefficient for the comparison of SLD and infrainguinal disease in the same limb was 0.1 (P = .69). At baseline, the limbs with severe SLD had the same degree of leg swelling and venous clinical severity score as the limbs with absent to mild SLD (P > .1) with similar improvements after stenting (P > .4). Seven limbs underwent complex decongestive therapy (all with severe SLD and concomitant severe infrainguinal disease in one) to treat significant residual leg edema, with improvement.

CONCLUSIONS

SLD appears to be common in patients with leg edema undergoing stenting for symptomatic CIVO. Such disease appears to affect the thoracic duct more commonly. Although patients with persistent or residual leg edema after stenting can benefit from complex decongestive therapy, further workup in the form of inguinal intranodal lymphangiography and targeted intervention might need to be considered for those who do not benefit from such therapy. Further study is warranted.

Lymphangiography and lymphatic embolisation for the treatment of chyle leaks after neck surgery: assessment of lymphangiography findings and embolisation techniques

OBJECTIVE

To assess lymphangiography findings and outcome of lymphatic embolisation to manage chyle leak after neck surgery.

METHODS

Consecutive cases of lymphangiography performed between April 2018 and May 2022 for management of chyle leaks related to neck surgery were retrospectively reviewed. Lymphangiography findings, techniques, and outcomes were analysed.

RESULTS

Eight patients (mean age: 46.5 years) were included. Six patients had undergone radical neck dissection for thyroid cancer, and two had undergone lymph node excision. Clinical presentations were: chyle drainage through Jackson Pratt catheters in five patients, lymphorrhea through surgical wounds in two, and enlarging lymphocele in one. Lymphangiography techniques included: inguinal lymphangiography in four patients, retrograde lymphangiography in three, and transcervical lymphangiography in one. Lymphangiography revealed leaks in the terminal thoracic duct in two patients, bronchomediastinal trunk in two, jugular trunk in three, and superficial neck channels in one. Embolisation techniques included: non-selective embolisation of terminal thoracic duct (n = 2), selective embolisation of the jugular trunk (n = 3), selective embolisation of the bronchomediastinal trunk (n = 2), and intranodal glue embolisation of superficial neck channels (n = 1). One patient underwent a repeat procedure. Chyle leak resolved in all patients over a mean of 4.6 days. No complication was encountered.

CONCLUSION

Lymphatic embolisation seems to be effective and safe in managing chyle leaks after neck surgery. Lymphangiography allowed for the categorisation of chyle leaks according to their location. Post-embolisation patency of the thoracic duct may be preserved in chyle leaks that do not directly involve the thoracic duct.

ADVANCES IN KNOWLEDGE

Lymphatic embolisation is safe and effective in managing chyle leaks after neck surgery. On lymphangiography, the location of contrast media extravasation may not be consistent. The technique for embolisation should be based on the location of the leak. Post-embolisation patency of the thoracic duct may be preserved in chyle leaks that do not directly involve the thoracic duct.

Back to the Future II-A Comprehensive Update on the Rapidly Evolving Field of Lymphatic Imaging and Interventions

ABSTRACT

Lymphatic imaging and interventional therapies of disorders affecting the lymphatic vascular system have evolved rapidly in recent years. Although x-ray lymphangiography had been all but replaced by the advent of cross-sectional imaging and the scientific focus shifted to lymph node imaging (eg, for detection of metastatic disease), interest in lymph vessel imaging was rekindled by the introduction of lymphatic interventional treatments in the late 1990s. Although x-ray lymphangiography is still the mainstay imaging technique to guide interventional procedures, several other, often less invasive, techniques have been developed more recently to evaluate the lymphatic vascular system and associated pathologies. Especially the introduction of magnetic resonance, and even more recently computed tomography, lymphangiography with water-soluble iodinated contrast agent has furthered our understanding of complex pathophysiological backgrounds of lymphatic diseases. This has led to an improvement of treatment approaches, especially of nontraumatic disorders caused by lymphatic flow abnormalities including plastic bronchitis, protein-losing enteropathy, and nontraumatic chylolymphatic leakages. The therapeutic armamentarium has also constantly grown and diversified in recent years with the introduction of more complex catheter-based and interstitial embolization techniques, lymph vessel stenting, lymphovenous anastomoses, as well as (targeted) medical treatment options. The aim of this article is to review the relevant spectrum of lymphatic disorders with currently available radiological imaging and interventional techniques, as well as the application of these methods in specific, individual clinical situations.

Prognostic significance of cervical radiologic carotid artery invasion by lymph node on magnetic resonance imaging in nasopharyngeal carcinoma

PURPOSE

Carotid artery invasion (CAI) has been demonstrated to be an important prognosticator in some head and neck cancers. This study aimed to examine the prognostic value of radiologic CAI (rCAI) by cervical lymphadenopathy in nasopharyngeal carcinoma (NPC).

METHODS

NPC patients treated between January 2013 and December 2016 were included. Pre-treatment MRIs were reviewed for cervical rCAI according to the radiologic criteria. Univariate and multivariate models were constructed to assess the association between cervical rCAI and clinical outcomes. A new N classification system was proposed and compared to the 8th AJCC system.

RESULTS

The percentage of patients with MRI-positive lymph nodes was 84.7% (494/583), of whom cervical rCAI cases accounted for 42.3% (209/494). Cervical rCAI was associated with significantly poorer OS, DFS, DFFS and RFFS compared to non-rCAI (P < 0.05). Multivariate analyses confirmed that cervical rCAI was an independent prognosticator for DFS and DFFS, surpassing other nodal features, such as laterality, size, cervical node necrosis (CNN) and radiologic extranodal extension (rENE), while location of positive LNs remained independently associated with OS, DFS and DFFS. We propose a refined N classification: New_N1: upper neck LNs only without cervical rCAI; New_N2: upper neck LNs only with cervical rCAI; New_N3: upper and lower LNs. The proposed classification broadened the differences in OS, DFS and DFFS between N1 and N2 disease, and achieved a higher c-index for DFS and DFFS.

CONCLUSIONS

Cervical rCAI was an independent unfavorable indicator of NPC. Compared to the AJCC system, the proposed N category showed satisfactory stratification between N1 and N2 disease, and better prediction of distant metastasis and disease failure.

How to Start a Lymphatic Program

Many patients are born with lymphatic abnormalities or are susceptible to pathology following cardiac surgery. It therefore becomes important to evaluate and treat lymphatic disorders in centers performing congenital heart surgery. Programs can make strides towards starting a lymphatic branch if appropriately equipped with proper staff, tools, and other capabilities to perform lymphatic system access, imaging, and intervention. In reality, many of these components already exist in most centers, and a successful and comprehensive program can be established by enlisting these already established services.

Current diagnostic and therapeutic strategies for the management of lymphatic insufficiency in patients with hypoplastic left heart syndrome

Children with hypoplastic left heart syndrome share unique hemodynamic features that alter lymphatic integrity at all stages of palliation. Lymphatic congestion is almost universal in this patient group to some extent. It may lead to reversal of lymphatic flow, the development of abnormal lymphatic channels and ultimately decompression and loss of protein rich lymphatic fluid into extra lymphatic compartments in prone individuals. Some of the most devastating complications that are associated with single ventricle physiology, notably plastic bronchitis and protein losing enteropathy, have now been proven to be lymphatic in origin. Based on the new pathophysiologic concept new diagnostic and therapeutic strategies have recently been developed. Dynamic contrast magnetic resonance lymphangiography is now mainstay in diagnosis of lymphatic insufficiency and allows a thorough assessment of anatomy and function of the main lymphatic compartments through intranodal, intrahepatic and intramesenteric lymphatic imaging. Contrast enhanced ultrasound can evaluate thoracic duct patency and conventional fluoroscopic lymphangiography has been refined for evaluation of patients where magnetic resonance imaging cannot be performed. Novel lymphatic interventional techniques, such as thoracic duct embolization, selective lymphatic duct embolization and liver lymphatic embolization allow to seal abnormal lymphatic networks minimally invasive and have shown to resolve symptoms. Innominate vein turn-down procedures, whether surgical or interventional, have been designed to reduce lymphatic afterload and increase systemic preload effectively in the failing Fontan circulation. Outflow obstruction can now be managed with new microsurgical techniques that create lympho-venous anastomosis. Short term results for all of these new approaches are overall promising but evidence is sparse and long-term outcome still has to be defined. This review article aims to summarize current concepts of lymphatic flow disorders in single ventricle patients, discuss new emerging diagnostic and therapeutic strategies and point out lacks in evidence and needs for further research on this rapidly growing topic.

Multidisciplinary Management of Chylothorax

Chylothorax, the accumulation of chyle in the pleural space, is usually caused by the disruption of the thoracic duct or its tributaries. Etiologies are broadly divided into traumatic, including postsurgical, and nontraumatic, most commonly in the setting of malignancy. The management of chylothorax largely depends on the cause and includes dietary modification and drainage of the pleural space. A definitive intervention, whether surgical or a percutaneous lymphatic intervention, should be considered in patients with a persistently high volume of chylous output and in those with a prolonged leak, before complications such as malnutrition ensue. No methodologically robust clinical trials guiding management are currently available. In this article, we review the current literature and propose a stepwise, evidence-based multidisciplinary approach to the management of patients with both traumatic and nontraumatic chylothorax.

Invasive treatment of persistent postoperative chylothorax secondary to thoracic duct variation injury: Two case reports and literature review

RATIONALE

Postoperative chylothorax is a rare complication after pulmonary resection. Thoracic duct variations may play a key role in postoperative chylothorax occurrence and make treatment difficult. No studies in the literature have reported the successful treatment of chylothorax second to thoracic duct variation by lipiodol-based lymphangiography.

PATIENT CONCERNS

A 63-year-old male and a 28-year-old female with primary lung adenocarcinoma were treated by video-assisted thoracoscopic cancer resection, and suffered postoperative chylothorax. Conservative treatment was ineffective, including nil per os, persistent thoracic drainage, fatty food restriction, and somatostatin administration.

DIAGNOSIS

Postoperative chylothorax.

INTERVENTIONS

Patients received lipiodol-based lymphangiography under fluoroscopic guidance. Iatrogenic injuries were identified at thoracic duct variations, including an additional channel in case 1 and the lymphatic plexus instead of the thoracic duct in case 2.

OUTCOMES

Thoracic duct variations were identified by lipiodol-based lymphangiography, and postoperative chylothorax was successfully treated by lipiodol embolizing effect.

LESSONS

Thoracic duct variations should be considered after the failure of conservative treatment for postoperative chylothorax secondary to pulmonary resection. Lipiodol-based lymphangiography is valuable for identifying the thoracic duct variations and embolizing chylous leakage.

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.

Interventional Management of Acquired Lymphatic Disorders

The lymphatic system is a complex network of tissues, vessels, and channels found throughout the body that assists in fluid balance and immunologic function. When the lymphatic system is disrupted related to idiopathic, iatrogenic, or traumatic disorders, lymphatic leaks can result in substantial morbidity and/or mortality. The diagnosis and management of these leaks is challenging. Modern advances in lymphatic imaging and interventional techniques have made radiology critical in the multidisciplinary management of these disorders. The authors provide a review of conventional and clinically relevant variant lymphatic anatomy and recent advances in diagnostic techniques such as MR lymphangiography. A detailed summary of technical factors related to percutaneous lymphangiography and lymphatic intervention is presented, including transpedal and transnodal lymphangiography. Traditional transabdominal access and retrograde access to the central lymph nodes and thoracic duct embolization techniques are outlined. Newer techniques including transhepatic lymphangiography and thoracic duct stent placement are also detailed. For both diagnostic and interventional radiologists, an understanding of lymphatic anatomy and modern diagnostic and interventional techniques is vital to the appropriate treatment of patients with acquired lymphatic disorders. ^©RSNA, 2022.

Lymphatic vessels in cancer

The lymphatic system, composed of initial and collecting lymphatic vessels as well as lymph nodes that are present in almost every tissue of the human body, acts as an essential transport system for fluids, biomolecules and cells between peripheral tissues and the central circulation. Consequently, it is required for normal body physiology but is also involved in the pathogenesis of various diseases, most notably cancer. The important role of tumor-associated lymphatic vessels and lymphangiogenesis in the formation of lymph node metastasis has been elucidated during the last two decades, whereas the underlying mechanisms and the relation between lymphatic and peripheral organ dissemination of cancer cells are incompletely understood. Lymphatic vessels are also important for tumor-host communication, relaying molecular information from a primary or metastatic tumor to regional lymph nodes and the circulatory system. Beyond antigen transport, lymphatic endothelial cells, particularly those residing in lymph node sinuses, have recently been recognized as direct regulators of tumor immunity and immunotherapy responsiveness, presenting tumor antigens and expressing several immune-modulatory signals including PD-L1. In this review, we summarize recent discoveries in this rapidly evolving field and highlight strategies and challenges of therapeutic targeting of lymphatic vessels or specific lymphatic functions in cancer patients.

Percutaneous Radiofrequency Ablation to Occlude the Thoracic Duct: Preclinical Studies in Swine for a Potential Alternative to Embolization

PURPOSE

To investigate the feasibility of percutaneous radiofrequency ablation (RFA) to occlude the thoracic duct (TD) in a swine model with imaging and histologic correlation.

MATERIALS AND METHODS

Six swine underwent TD RFA. Two terminal (4 hours; 1 open, 1 percutaneous) and four survival (30 days; all percutaneous) studies were performed. Two 20-gauge needles were placed adjacent to the TD under direct visualization after right thoracotomy or under fluoroscopic guidance using a percutaneous transabdominal approach after intranodal lymphangiography. Radiofrequency electrodes were advanced through the needles and ablation was performed at 90 degrees Celsius for 90 seconds. Lymphangiography was performed and the TD and adjacent structures were resected and examined microscopically at the end of each study period.

RESULTS

Four of six subjects survived the planned study period and underwent follow up lymphangiography. Two subjects in the survival group were euthanized early; 1 after developing an acute chylothorax and 1 due to gastric volvulus 14 days after ablation. Occlusion of the targeted TD segment was noted on lymphangiography in 3 of 4 remaining subjects (2 acute, 1 survival). Histology 4 hours after RFA demonstrated necrosis of the TD wall and hemorrhage within the lumen. Histology at 14 and 30 days revealed fibrosis with hemosiderin laden macrophages replacing the ablated TD. Collagen degeneration within the aortic wall involving a maximum of 60% thickness was noted in 5/6 subjects.

CONCLUSION

Percutaneous RFA can achieve short-segment TD occlusion. Further study is needed to improve safety and demonstrate clinical efficacy in treating TD leaks.

Postmortem Retrograde Contrasted Infusion in Thoracic Duct Outflow: Imaging Effectiveness Analysis

Background

Thoracic duct (TD) anomaly can be quite variable and dangerous in surgical interventions in the neck region as there are numerous variations in its formation and topography. This highlights the importance of full knowledge about the TD and its anatomical variations. Thus, it is important to emphasize that the lack of anatomical-clinical knowledge or surgical skill during an intervention can significantly hamper successful results. The present study aimed to perform radiopaque contrast infusion into the TD of intact cadavers, either formalinized or refrigerated, to evaluate possible lymphatic architecture patterns via reverse lymphography.

Methodology

TD dissection was performed on 13 cadaveric specimens. After isolating the lymphatic vessel, it was cannulated with an nº 4 urethral probe fixed with cordonnet cotton. Then, a 10 mL syringe was attached to the urethral probe and the radiopaque iodinated contrast was injected into the TD under constant and gradual manual pressure.

Results

TD outflow was detected on the posterior surface of the junction between the internal jugular and the left subclavian veins, either as direct outflow (in 10 cases) or as an arc (in three cases). Reverse contrast progression was impossible in each of the attempts, probably due to valvular resistance and lumen obliteration, which completely prevented pressure infusion into the thoracic and abdominal parts of the TD.

Conclusions

We emphasize the impracticality of obtaining postmortem radiopaque images via retrograde contrast injection into the TD in formalinized or refrigerated bodies.

Understanding Lymphatic Anatomy and Abnormalities at Imaging

Lymphatic abnormalities encompass a wide range of disorders spanning solitary common cystic lymphatic malformations (LMs) to entities involving multiple organ systems such as lymphangioleiomyomatosis. Many of these disorders are rare, yet some, such as secondary lymphedema from the treatment of malignancy (radiation therapy and/or lymph node dissection), affect millions of patients worldwide. Owing to complex and variable anatomy, the lymphatics are not as well understood as other organ systems. Further complicating this is the variability in the description of lymphatic disease processes and their nomenclature in the medical literature. In recent years, medical imaging has begun to facilitate a deeper understanding of the physiology and pathologic processes that involve the lymphatic system. Radiology is playing an important and growing role in the diagnosis and treatment of many lymphatic conditions. The authors describe both normal and common variant lymphatic anatomy. Various imaging modalities including nuclear medicine lymphoscintigraphy, conventional lymphangiography, and MR lymphangiography used in the diagnosis and treatment of lymphatic disorders are highlighted. The authors discuss imaging many of the common and uncommon lymphatic disorders, including primary LMs described by the International Society for the Study of Vascular Anomalies 2018 classification system (microcystic, mixed, and macrocystic LMs; primary lymphedema). Secondary central lymphatic disorders are also detailed, including secondary lymphedema and chylous leaks, as well as lymphatic disorders not otherwise easily classified. The authors aim to provide the reader with an overview of the anatomy, pathology, imaging findings, and treatment of a wide variety of lymphatic conditions. ^©RSNA, 2022.

Dynamic contrast-enhanced magnetic resonance lymphangiography

Lymphatic flow disorders include a broad spectrum of abnormalities that can originate in the lymphatic or the venous system. The development of these disorders is multifactorial and is most commonly associated with congenital heart diseases and palliative surgeries that these patients undergo. Central lymphatic disorders might be secondary to traumatic leaks, lymphatic overproduction, conduction abnormalities or lymphedema, and they can progress to perfusion anomalies. Several imaging modalities have been used to visualize the lymphatic system. However, the imaging of central lymphatic flow has always been challenging. Dynamic contrast-enhanced magnetic resonance lymphangiography (DCMRL) allows for visualization of central lymphatic flow disorders and has been recently applied for the assessment of plastic bronchitis, protein-losing enteropathy, chylothorax and chylopericardium, among other lymphatic disorders. The hepatic and mesenteric accesses are innovative and promising techniques for better identification and understanding of these abnormalities. The main objectives of this review are to discuss the physiology and anatomy of the lymphatic system and review the current uses of DCMRL in the diagnosis and management of lymphatic flow disorders.

Lymphatic osteopathic manipulative treatment reduces duration of deltoid soreness after Pfizer/BioNTech COVID-19 vaccine

Pfizer-BioNTech BNT162b2 is one of the three U.S. Food and Drug Administration (FDA)-approved vaccines for the prevention of COVID-19. Its most common side effect, injection site pain, occurs because of locally recruited inflammatory mediators and is mitigated by the lymphatic system. Side effects may discourage individuals from receiving vaccines; therefore, reducing the duration of injection site pain can promote vaccination compliance. Osteopathic manipulative treatments (OMT) can directly affect the physiology underlying muscle soreness; however, there is currently no literature that supports the use of OMT in this scenario. In this case report, an otherwise healthy male presented with acute left deltoid soreness after receiving the Pfizer COVID-19 vaccine. The pain began 5 h prior to the visit. Three hours after being treated with lymphatic OMT, the severity of the pain was significantly reduced and was alleviated 8h after onset in comparison to the median duration of 24-48 h. He received his second dose 3 weeks later. This case report can provide future studies with the groundwork for further investigating the role of OMT in treating postvaccination muscle soreness, which can improve patient satisfaction and potentially promote vaccination compliance.

Bilateral Renal Lymphangiectasia with No Significant Morbidity for Over 25 Years: A Case Report

Patient: Female, 39-year-old

Final Diagnosis: Lymphangiectasia

Symptoms: Pain

Medication: —

Clinical Procedure: —

Specialty: Urology

Bilateral Chylothorax Following Total Thyroidectomy with Neck Dissection for Papillary Thyroid Cancer: Case report

Bilateral chylothorax is a rare condition that occurs after a thyroidectomy and neck dissection, which can lead to severe morbidity and, potentially, death, if not managed properly. We report a rare complication of neck surgery and subsequent bilateral pleural effusion in a 35-year-old female patient who presented at Sultan Qaboos University Hospital in 2018 with shortness of breath and respiratory distress. The bilateral pleural effusion and related symptoms occurred one week after a total thyroidectomy with central and left lateral neck dissection. The patient was managed conservatively and subsequently recovered.

Prophylactic ligation of the opacified thoracic duct in minimally invasive esophagectomy - feasibility and safety

BACKGROUND

Chyle leak is a rare but morbid complication of esophagectomy. We assessed the feasibility of visualization and prophylactic ligation of the opacified thoracic duct (TD) after administration of 50 ml of olive oil.

METHODS

This prospective single center study considered all patients with carcinoma of the middle and lower thirds of the thoracic esophagus including the gastroesophageal junction (GEJ), managed from January 2018 to December 2019, for inclusion. All patients underwent McKeown minimally invasive esophagectomy. After anesthesia and endotracheal intubation, 50 ml of olive oil was administered through a nasogastric (NG) tube. During thoracoscopic esophageal mobilization, the opacified thoracic duct was identified and ligated using Weck Hem-o-lok clips immediately above the diaphragmatic hiatus. Postoperatively, the nature, volume, and triglyceride levels of the fluid from the chest drain were recorded.

RESULTS

Forty-three patients with carcinoma of the esophagus were assessed for inclusion and eventually, 33 were enrolled. The median age of the study population was 55 years, and there were 20 males. The tumor site was the lower esophagus in 24 (72.7%) patients. The most common histolopathological finding was squamous cell carcinoma (97%). The opacified thoracic duct could be identified and ligated in 31 (93.9%) patients. The median duration from the administration of olive oil to the ligation of the thoracic duct was 100 min. The median chest drain output and triglyceride levels on postoperative day (POD) one were 250 ml and 48 mg% respectively. No patient developed postoperative chylothorax.

CONCLUSION

Opacification and visualization of the thoracic duct during thoracoscopy can be aided by administering olive oil. Ligation of this opacified duct is feasible and safe.

SLIDE-Novel Approach to Apocrine Sweat Sampling for Lipid Profiling in Healthy Individuals

We designed a concept of 3D-printed attachment with porous glass filter disks—SLIDE (Sweat sampLIng DevicE) for easy sampling of apocrine sweat. By applying advanced mass spectrometry coupled with the liquid chromatography technique, the complex lipid profiles were measured to evaluate the reproducibility and robustness of this novel approach. Moreover, our in-depth statistical evaluation of the data provided an insight into the potential use of apocrine sweat as a novel and diagnostically relevant biofluid for clinical analyses. Data transformation using probabilistic quotient normalization (PQN) significantly improved the analytical characteristics and overcame the ‘sample dilution issue’ of the sampling. The lipidomic content of apocrine sweat from healthy subjects was described in terms of identification and quantitation. A total of 240 lipids across 15 classes were identified. The lipid concentrations varied from 10⁻¹⁰ to 10⁻⁴ mol/L. The most numerous class of lipids were ceramides (n = 61), while the free fatty acids were the most abundant ones (average concentrations of 10⁻⁵ mol/L). The main advantages of apocrine sweat microsampling include: (a) the non-invasiveness of the procedure and (b) the unique feature of apocrine sweat, reflecting metabolome and lipidome of the intracellular space and plasmatic membranes. The SLIDE application as a sampling technique of apocrine sweat brings a promising alternative, including various possibilities in modern clinical practice.

An unusual complication of tumor surgery: chylous leakage

PURPOSE

This study was designed to evaluate the effectiveness of conservative treatment for chylous leak after tumor surgery and to propose a management algorithm.

METHODS

The data of patients with postoperative chylous leak after tumor surgery in our institution between 2010 and 2019 were retrospectively reviewed. In this study, 469 laparotomies, 89 thoracotomies, and 57 cervical excisions were performed for tumor surgery in our institution.

RESULTS

Twelve patients with a median age of 4 (IQR, 3-8) years had postoperative chylous leak. All patients received total parenteral nutrition for a median of 13 days. Five patients had intravenous somatostatin for a median of 14 days (IQR, 9-16) to decrease chyle production. Eventually, chylous leak ceased in all patients with conservative treatment and surgical drains were removed after no leak was observed with enteral feeding.

CONCLUSIONS

The incidence of chylous leak in childhood tumor surgery is approximately 2%. Extended tumor resection and lymph node dissection lead to the injury of the delicate structures that drain chyle. Conservative treatment with total parenteral nutrition and somatostatin seems to be effective. In particular, somatostatin may be used in resistant cases. Conservative treatment can take up to 1 month. The algorithm consists of how to manage postoperative chylous leak in childhood.

Lipiodol lymphangiography as a treatment for refractory postoperative chylothorax: a case report

Postoperative chylothorax is the most frequent cause of traumatic thoracic chyle leakage. Conservative treatment is primarily used to treat low flow rate chylothoraces and should be initiated as soon as the diagnosis has been made. In case of high flow rate chylothorax or failure of initial treatment, surgery and radiological treatment are indicated. Despite this fact, there is a lack of consensus regarding the best therapeutic option to choose. In the case reported herein, a postoperative chylothorax with a low flow chyle leakage which didn't respond to conservative treatment is demonstrated. We used lipiodol lymphangiography to determine the site of chyle leakage and to successfully treat our patient. Risk factors for non-response to conservative treatment are also discussed.

Traumatic chylothorax: a dilemma to surgeons and interventionists

Chylothorax is generally seen due to iatrogenic injury to the thoracic duct during thoracic or neck surgery. It can also be encountered secondary to chest trauma either blunt or penetrating. Percutaneous thoracic duct embolisation is an alternative to surgical treatment and is considered an effective and safe minimally invasive treatment option for chylothorax with a success rate of about 80%. We present a case of blunt trauma to the chest with chylothorax, which was successfully managed with transvenous retrograde thoracic duct embolisation.

Temporal evolution of metastatic disease: part I-an in-depth review of the evolution of metastatic disease across diverse spectrum of non-neural solid tumors on serial oncologic imaging studies and relevant practical applications

With improved survival rates of patients with metastatic disease due to continuously evolving multimodality treatment options, radiologists are increasingly interpreting imaging studies from patients with protracted metastatic disease. It is thus crucial for radiologists to have an in-depth understanding of the temporal evolution of metastatic spread and the accompanying findings on imaging studies, to provide accurate interpretation that supports optimal management. A general overview of the evolution of cancer spread on serial imaging studies and common pathways of tumor spread across multiple tumor types and tumor locations is not readily available in radiology literature. The key common pathways of tumor spread across diverse spectrum of tumors relevant to radiologists are summarized in a logical schematic approach which focusses on aiding radiologists to understand the pathways of spread resulting in current sites of metastatic disease involvement and then to potentially predict future sites of metastatic involvement. This article also summarizes the practical applications of this knowledge to the routine oncologic imaging interpretation.

Lymphangiography and Lymphatic Interventions

Compared with the traditional pedal lymphangiography, intranodal lymphangiography and MR lymphangiography have made imaging of the lymphatic system less challenging. Improvements in imaging and availability of newer catheters have allowed embolization of lymphatic system much more feasible that previously envisioned. In this article, we briefly review the anatomy, imaging, and current and future of lymphatic interventions.

Chylothorax post transaxillary first rib resection for thoracic outlet syndrome

We present a patient who developed high output chyle leak post left transaxillary first rib resection for venous thoracic outlet syndrome. The high output chylorrhoea was successfully treated by conservative measures, bed rest, parenteral nutrition and low-fat diet. The patient was discharged after an 18-day hospital stay with a complete resolution of his chylous fistula prior to discharge. This is the first documented chylothorax post transaxillary first rib resection likely due to anomalous chyle anatomy.

Lymphovenous shunts: from development to clinical applications

The lymphatic system is a vast network of vessels that functions to return excess fluid from the interstitial space to the blood stream. Lymphovenous shunts are anastomoses, either natural or surgical, that connect the lymphatic and venous systems. Connections between the thoracic duct and venous system or between the right lymphatic duct and venous system are prime examples of anatomic lymphovenous shunts. Lymphovenous shunts are also present peripherally in tissues such as lymph nodes. Furthermore, pathologic lymphovenous shunts are observed in conditions such as lymphedema, malignancy, and lymphovenous malformations. Surgically, lymphovenous shunts may be constructed as an approach to treat lymphedema. Here, we discuss anatomic and surgical lymphovenous shunts in the context of normal development and disease. This perspective is intended to give an understanding of the role of lymphovenous shunts in health and disease and to show how they can be leveraged to treat disease surgically.

Perioperative and Postoperative Complications of Supraclavicular, Ultrasound-Guided, Totally Implantable Venous Access Port via the Brachiocephalic Vein in Adult Patients: A Retrospective Multicentre Study

PURPOSE

The totally implantable venous access port (TIVAP) provides patients with safe, effective and long-term convenient venous access for the administration of medications such as chemotherapy drugs. The implantation and long-term use of TIVAP are related to thrombosis, infection and other complications. In this study, the medical records of multicentre patients were collected, and the perioperative and postoperative complications were retrospectively analysed to objectively evaluate the safety of the implantation of supraclavicular, ultrasound-guided TIVAP via the brachiocephalic vein (BCV).

PATIENTS AND METHODS

We retrospectively analysed the clinical data of 433 adult patients who had undergone ultrasound-guided TIVAP implantation via the BCV at four hospitals in China from March 2018 to May 2019. The success rates of the first puncture, operation time, and perioperative and postoperative complications were analysed.

RESULTS

All the TIVAPs were implanted successfully (100%). The average TIVAP carrying time was 318.15 ±44.22 days (range: 38-502 days) for a total of 197,694 catheter days. The success rate of the first puncture was 94.92% (411/433), and the average operation time was 29.66 ±7.45 min (range: 18-60 min). The perioperative complications included arterial puncture in 4 patients and pneumothorax in 1 patient. The incidence of postoperative complications was 5.08% (22/433), including poor incision healing (n = 2), catheter-related infection (n = 3), port infection (n = 6), thrombosis (n = 2) and fibrin sheath formation (n = 8). Another patient had infusion disturbance 2 days after the operation, and chest X-ray showed bending at the connection between the catheter and port. No other serious complications occurred, such as catheter rupture and drug leakage. The total incidence of complications was 6.24% (27/433).

CONCLUSION

This study showed excellent tolerance of supraclavicular, ultrasound-guided BCV puncture to implant TIVAP and a low incidence of complications. As a safe and effective method of TIVAP implantation, it can provide a new choice for clinicians.

Lymphatic Disorders and Management in Patients with Congenital Heart Disease

Congenital heart disease can lead to significant lymphatic complications such as chylothorax, plastic bronchitis, protein losing enteropathy and ascites. Recent improvements in lymphatic imaging and the development of new lymphatic procedures can help alleviate symptoms and improve outcomes.

Management options for post-esophagectomy chylothorax

Chylothorax, although an uncommon complication of esophagectomy, is associated with high morbidity and mortality if not treated promptly. Consequently, knowledge of the thoracic duct (TD) anatomy is essential to prevent its inadvertent injury during surgery. If the TD is injured, early diagnosis and immediate intervention are of paramount importance; however, there is still no universal consensus about the management of post-operative chylothorax. With increasing advances in the spheres of interventional radiology and minimally invasive surgery, there are now several options for managing TD injury. We review this topic in detail to provide a comprehensive and practical overview to help surgeons manage this challenging complication. In particular, we discuss an appropriate step-up approach to prevent the morbidity associated with open surgery as well as the metabolic, nutritional, and immunological disorders that accompany a prolonged illness.

Lymphatic Anatomy and Physiology

Lymphatics have long been overshadowed by the remainder of the circulatory system. Historically, lymphatics were difficult to study because of their small and indistinct vessels, colorless fluid contents, and limited effective interventions. However, the past several decades have brought increased funding, advanced imaging technologies, and novel interventional techniques to the field. Understanding the history of lymphatic anatomy and physiology is vital to further realize the role lymphatics play in most major disease pathologies and innovate interventional solutions for them.

Risk Factors and Patterns of Abdominal Lymph Node Recurrence After Radical Surgery for Locally Advanced Thoracic Esophageal Squamous Cell Cancer

Background

We aimed to identify the suitable indication and delineate the target volume based on the pattern of abdominal lymph node recurrence (ALNR) after radical surgery for guiding postoperative radiotherapy in thoracic esophageal squamous cell cancer (TESCC).

Methods

Clinical data of patients with locally advanced TESCC after radical surgery without perioperative anti-tumor therapies from June 2011 to June 2016 were reviewed. Logistic regression analysis was used to find out the high-risk factors of ALNR. The pattern of ALNR was analysed and a template CT in the Pinnacle treatment plan system was used to reconstruct the distribution of the sites of ALNR.

Results

A total of 63 (19.57%) patients with 276 lymph nodes of ALNR were identified in 322 patients. Univariate logistic regression indicated that pathological tumor location, width of tumor, T stage, N stage, TNM stage, ratio of lymph node metastasis (LNM), vessel carcinoma embolus, cancerous node, LNM in the middle and lower mediastinum, LNM in the abdominal region, ratio of LNM in the abdominal region were risk factors of ALNR. Multivariate logistic regression analysis showed that only LNM in the abdominal region was an independent risk factor. The odds ratio was 7.449 (95% CI=2.552–22.297, P<0.001). Station 16a2, station 9, station 16b1, and station 8 were the major regions of ALNR. The recurrence rates were 10.56%, 9.63%, 7.14% and 5.28% in these stations, respectively.

Conclusion

Positive pathological abdominal lymph nodes should be the major indication for abdominal irradiation in postoperative radiotherapy for locally advanced TESCC. We recommended that the target volume includes station 8, station 9, station 16a2 and station 16b1 and proposed a specific delineation of the clinical target volume based on the distribution of ALNR on template CT images.

Proteolysis and Oxidation of Therapeutic Proteins After Intradermal or Subcutaneous Administration

The intradermal (ID) and subcutaneous (SC) routes are commonly used for therapeutic proteins (TPs) and vaccines; however, the bioavailability of TPs is typically less than small molecule drugs given via the same routes. Proteolytic enzymes in the dermal, SC, and lymphatic tissues may be responsible for the loss of TPs. In addition, the TPs may be exposed to reactive oxygen species generated in the SC tissue and the lymphatic system in response to injection-related trauma and impurities within the formulation. The reactive oxygen species can oxidize TPs to alter their efficacy and immunogenicity potential. Mechanistic understandings of the dominant proteolysis and oxidative routes are useful in the drug discovery process, formulation development, and to assess the potential for immunogenicity and altered pharmacokinetics (PK). Furthermore, in vitro tools representing the ID or SC and lymphatic system can be used to evaluate the extent of proteolysis of the TPs after the injection and before systemic entry. The in vitro clearance data may be included in physiologically based pharmacokinetic models for improved PK predictions. In this review, we have summarized various physiological factors responsible for proteolysis and oxidation of TPs after ID and SC administration.

Understanding the Monoclonal Antibody Disposition after Subcutaneous Administration using a Minimal Physiologically based Pharmacokinetic Model

PURPOSE

Monoclonal antibodies (mAbs) are commonly administered by subcutaneous (SC) route. However, bioavailability is often reduced after SC administration. In addition, the sequential transfer of mAbs through the SC tissue and lymphatic system is not completely understood. Therefore, major objectives of this study were a) To understand absorption of mAbs via the lymphatic system after SC administration using physiologically based pharmacokinetic (PBPK) modeling, and b) to demonstrate application of the model for prediction of SC pharmacokinetics (PK) of mAbs.

METHODS

A minimal PBPK model was constructed using various physiological parameters related to the SC injection site and lymphatic system. The remainder of the body organs were represented using a 2-compartment model (central and peripheral compartments), with parameters derived from available intravenous (IV) PK data. The IV and SC clinical PK data of a total of 10 mAbs were obtained from literature. The SC PK data were used to estimate the lymphatic trunk-lymph node (LN) clearance.

RESULTS

The mean estimated lymphatic trunk-LN clearance obtained from 37 SC PK profiles of mAbs was 0.00213 L/h (0.001332 to 0.002928, 95% confidence intervals). The estimated lymphatic trunk-LN clearance was greater for the mAbs with higher isoelectric point (pI). In addition, the estimated clearance increased with decrease in the bioavailability.

CONCLUSION

The minimal PBPK model identified SC injection site lymph flow, afferent and efferent lymph flows, and volumes associated with the SC injection site, lymphatic capillaries and lymphatic trunk-LN as important physiological parameters governing the absorption of mAbs after SC administration. The model may be used to predict PK of mAbs using the relationship of lymphatic trunk-LN clearance and the pI. In addition, the model can be used as a bottom platform to incorporate SC and lymphatic in vitro clearance data for mAb PK prediction in the future.

Therapeutic delivery to the peritoneal lymphatics: Current understanding, potential treatment benefits and future prospects

The interest in approaches to deliver therapeutics to the lymphatic system has increased in recent years as the lymphatics have been discovered to play an important role in a range of disease states such as cancer metastases, inflammatory and metabolic disease, and acute and critical illness. Therapeutic delivery to lymph has the potential to enhance treatment of these conditions. Currently much of the existing data explores therapeutic delivery to the lymphatic vessels and nodes that drain peripheral tissues and the intestine. Relatively little focus has been given to understanding the anatomy, function and therapeutic delivery to the peritoneal lymphatics. Gaining a better understanding of peritoneal lymphatic structure and function would contribute to the understanding of disease processes involving these lymphatics and facilitate the development of delivery systems to target therapeutics to the peritoneal lymphatics. This review explores the basic anatomy and ultrastructure of the peritoneal lymphatics system, the lymphatic drainage pathways from the peritoneum, and therapeutic and delivery system characteristics (size, lipophilicity and surface properties) that favour lymph uptake and retention after intraperitoneal delivery. Finally, techniques that can be used to quantify uptake into peritoneal lymph are outlined, providing a platform for future studies.

Interventional Therapies for Thoracic Duct Injury and Intractable Chylothorax

Injury to the thoracic duct with resultant chylothorax can cause significant patient morbidity and mortality. Conservative treatment strategies often fail to address the problem. Open surgical and percutaneous approaches are often required to manage patients with refractory chylothorax. This review describes in detail the major role of minimally invasive interventional therapies for thoracic duct (TD) injury. The review emphasizes strategies for identifying the TD on preprocedural imaging and describes various techniques for percutaneous access to the TD. The advantages and disadvantages of several approaches for accessing the duct are discussed. The technique of duct embolization is highlighted. The role of the minimally invasive percutaneous approach over open surgical approaches is discussed with a review of clinical outcomes, as reported in the literature. This review will also briefly discuss the surgical approach to TD ligation.

Combination Surgery of Silicone Tube Intubation and Conjunctival Resection in Patients with Epiphora

Purpose

To compare the success rates of performing only silicone tube intubation versus carrying out both conjunctival resection and silicone tube intubation.

Methods

The subjects of this study involved 62 patients (96 eyes) between October 2015 and May 2017 who were diagnosed as having punctal stricture or nasolacrimal duct stenosis. Out of 96 eyes, 47 underwent only silicone tube intubation, and 49 underwent both silicone tube intubation and conjunctival resection. Three parameters were measured at 1, 3, and 6 months after the surgery: the area of the tear meniscus using RTVue-100 anterior segment optical coherence tomography, the height of the tear meniscus using a slit lamp microscope, and the subjective satisfaction of patients as a result of improved sympotms like epiphora. The surgery was considered successful when the patients' experienced the resolution of symptoms and reduction of the area and height of the tear meniscus.

Results

The area of the tear meniscus, height of the tear meniscus, and subjective satisfaction of patients was superior in the group that underwent both silicone tube intubation and conjunctival resection compared silicone tube intubation only. Based on these results, the success rate of the surgery was 68.9% in the group that underwent only silicone tube intubation and 78.7% in the group that underwent both silicone tube intubation and conjunctival resection.

Conclusions

The resection of relaxed plica semilunares seems to increase the success rate of silicone tube intubation through the reduction of the area and height of the tear meniscus. Therefore, after determining the degree of conjunctivochalasis, if it was found to be severe, a combination with conjunctival resection was expected to increase the success rate of the surgery.

Quantitative Metastatic Lymph Node Regions on Magnetic Resonance Imaging Are Superior to AJCC N Classification for the Prognosis of Nasopharyngeal Carcinoma

Purpose

Quantitative lymph node burden has been demonstrated to be a critical prognosticator in various malignancies, yet it was seldom explored in nasopharyngeal carcinoma (NPC). This study aimed to investigate the impact of the number of metastatic lymph node regions (LRN) on prognosis of NPC and to establish a new N classification system based on LRN.

Methods and Materials

The magnetic resonance images (MRI) of 354 nondisseminated NPC patients before radical treatment were retrospectively evaluated. The regions with positive lymph nodes (LNs) were quantified according to 2013 updated guidelines for neck node levels. Prognostic value of LRN on distant metastasis-free survival (DMFS) was analyzed using multivariable Cox model after adjusting for other nodal characteristics and therapeutic factors.

Results

LRN strongly correlated with the size, laterality, level, extracapsular extension (ECE), and necrosis of LNs. Risk of distant metastasis significantly escalated with increased LRN (P<0.001). 5-year DMFS for LRN 0-1, 2-6, and ⩾7 was 97.0%, 86.7%, and 69.7%, respectively. In multivariable Cox analysis, LRN (HR 2.45; 95% CI 1.55-3.88; P<0.001) and maximal LN diameter (MLD) >6cm (HR 4.11; 95% CI 2.23-7.56; P<0.001) were identified as independent predictors of DMFS. Laterality and level showed no prognostic significance when accounting for LRN. A novel N classification scheme was derived by recursive partitioning analysis based on LRN and MLD. Compared with the 7th and 8th edition of American Joint Committee on Cancer (AJCC) systems, the new stratification exhibited better accuracy in predicting survivals.

Conclusions

LRN is a promising quantitative predictor of survival in NPC, eclipsing other classic LN characteristics in prognostic value. The simplified N classification scheme with LRN and MLD is predictive and practical, thus warranting further validation in future.

Anatomy of lymphatic drainage of the esophagus and lymph node metastasis of thoracic esophageal cancer

The lymphatic drainage of the inner layers (mucosa and submucosa) and the outer layers (muscularispropria and adventitia) of the thoracic esophagus is different. Longitudinal lymphatic vessels and long drainage territory in the submucosa and lamina propria should be the bases for bidirectional drainage and direct drainage to thoracic duct and extramural lymph nodes (LN). The submucosal vessels for direct extramural drainage are usually thick while lymphatic communication between the submucosa and intermuscular area is usually not clearly found, which does not facilitate transversal drainage to paraesophageal LN from submucosa. The right paratracheal lymphatic chain (PLC) is well developed while the left PLC is poorly developed. Direct drainage to the right recurrent laryngeal nerve LN and subcarinal LN from submucosa has been verified. Clinical data show that lymph node metastasis (LNM) is frequently present in the lower neck, upper mediastinum, and perigastric area, even for early-stage thoracic esophageal cancer (EC). The lymph node metastasis rate (LNMR) varies mainly according to the tumor location and depth of tumor invasion. However, there are some crucial LN for extramural relay which have a high LNMR, such as cervical paraesophageal LN, recurrent laryngeal nerve LN, subcarinal LN, LN along the left gastric artery, lesser curvature LN, and paracardial LN. Metastasis of thoracic paraesophageal LN seems to be a sign of more advanced EC. This review gives us a better understanding about the LNM and provides more information for treatments of thoracic EC.

Interplay of Tumor Spread, Volume and Epstein-Barr Virus DNA in Nasopharyngeal Carcinoma: Feasibility of An Integrative Risk Stratification Scheme

Purpose: To investigate the inter-correlation of tumor spread, volume and quantitative plasma Epstein-Barr virus DNA level (pEBV DNA), and to further assess the prognostic efficacy of a novel risk stratification combining anatomic, volumetric and biological features in nasopharyngeal carcinoma (NPC).

Methods and Materials: One hundred and twelve patients with non-metastatic NPC were prospectively enrolled. Correlation of pEBV DNA with tumor invasiveness, lymph node (LN) metastasis, tumor volume and classification was tested by univariate and multivariate analyses. 5-year distant metastasis free survival (DMFS) was evaluated using Kaplan-Meier method and Cox proportional hazards model.

Results: Tumor volume, TNM stage and pEBV DNA were strongly inter-correlated to each other. Nodal volume, skull base invasion and LN metastasis to supraclavicular fossa were determined to be independent predictors for pEBV DNA level. To exclude collinearity, a risk stratification based on combination of EBV DNA, nodal volume and anatomic features was established, offering significant distinguishing ability in 5-year DMFS. Further multivariate Cox regression analysis found the novel stratification to be independent predictor of DMFS.

Conclusions: Both anatomic spread and tumor volume contribute to pEBV DNA level, leading to strong inter-correlation between NPC stage, volume and EBV DNA. The proposed risk stratification combining anatomic, volumetric and biological features showed potential in refining DMFS prediction.

The anatomy and physiology of the terminal thoracic duct and ostial valve in health and disease: potential implications for intervention

The thoracic duct (TD) transports lymph drained from the body to the venous system in the neck via the lymphovenous junction. There has been increased interest in the TD lymph (including gut lymph) because of its putative role in the promotion of systemic inflammation and organ dysfunction during acute and critical illness. Minimally invasive TD cannulation has recently been described as a potential method to access TD lymph for investigation. However, marked anatomical variability exists in the terminal segment and the physiology regarding the ostial valve and terminal TD is poorly understood. A systematic review was conducted using three databases from 1909 until May 2017. Human and animal studies were included and data from surgical, radiological and cadaveric studies were retrieved. Sixty-three articles from the last 108 years were included in the analysis. The terminal TD exists as a single duct in its terminal course in 72% of cases and 13% have multiple terminations: double (8.5%), triple (1.8%) and quadruple (2.2%). The ostial valve functions to regulate flow in relation to the respiratory cycle. The patency of this valve found at the lymphovenous junction opening, is determined by venous wall tension. During inspiration, central venous pressure (CVP) falls and the valve cusps collapse to allow antegrade flow of lymph into the vein. During early expiration when CVP and venous wall tension rises, the ostial valve leaflets cover the opening of the lymphovenous junction preventing antegrade lymph flow. During chronic disease states associated with an elevated mean CVP (e.g. in heart failure or cirrhosis), there is a limitation of flow across the lymphovenous junction. Although lymph production is increased in both heart failure and cirrhosis, TD lymph outflow across the lymphovenous junction is unable to compensate for this increase. In conclusion the terminal TD shows marked anatomical variability and TD lymph flow is controlled at the ostial valve, which responds to changes in CVP. This information is relevant to techniques for cannulating the TD, with the aid of minimally invasive methods and high resolution ultrasonography, to enable longitudinal physiology and lymph composition studies in awake patients with both acute and chronic disease.

Targeting lymphatic function as a novel therapeutic intervention for rheumatoid arthritis

Although clinical outcomes for patients with rheumatoid arthritis (RA) have greatly improved with the use of biologic and conventional DMARDs, approximately 40% of patients do not achieve primary clinical outcomes in randomized trials, and only a small proportion achieve lasting remission. Over the past decade, studies in murine models point to the critical role of the lymphatic system in the pathogenesis and therapy of inflammatory-erosive arthritis, presumably by the removal of catabolic factors, cytokines and inflammatory cells from the inflamed synovium. Murine studies demonstrate that lymphatic drainage increases at the onset of inflammatory-erosive arthritis but, as inflammation progresses to a more chronic phase, lymphatic clearance declines and both structural and cellular changes are observed in the draining lymph node. Specifically, chronic damage to the lymphatic vessel from persistent inflammation results in loss of lymphatic vessel contraction followed by lymph node collapse, reduced lymphatic drainage, and ultimately severe synovitis and joint erosion. Notably, clinical pilot studies in patients with RA report lymph node changes following treatment, and thus draining lymphatic vessels and nodes could represent a potential biomarker of arthritis activity and response to therapy. Most importantly, targeting lymphatics represents an innovative strategy for therapeutic intervention for RA.