Systematic literature review of lymphatic imaging-guided procedural management of Noonan syndrome

OBJECTIVES

To assess through literature case analysis how advances in lymphatic imaging, interventional radiology, and lymphatic vascular microsurgery illuminate and improve the lymphatic-flow status in select patients with Noonan syndrome (NS) who have undergone surgical intervention as a part of their comprehensive and individualized treatment plan. Also, we sought to illustrate the spectrum of lymphatic complications that can occur in this patient population when lymphatic flow through abnormal vasculature is surgically disrupted.

METHODS

A literature review was performed by searching "Noonan AND Lymphatic AND Imaging" in the PubMed database. Inclusion criteria for this study were (1) diagnosis and clinical description of at least one original patient with NS, (2) imaging figures depicting lymphatic structure and function or a description of lymphatic imaging findings when a figure is not present, and (3) documentation of either lymphatic surgical intervention or lymphatic complications resulting from other procedures. Patient cases were first grouped by documented surgical intervention type, then clinical outcomes and lymphatic imaging results were compared.

RESULTS

A total of 18 patient cases from 10 eligible publications were included in our review. Lymphatic imaging findings across all patients included lymphatic vessel dysplasia along with flow disruption (n = 16), thoracic duct malformations (n = 12), dermal lymphatic reflux (n = 7), and dilated lymphatic vessels (n = 4). Lymphovenous anastomosis (n = 4) resulted in rapid improvement of patient symptoms and signs. New-onset lymphatic manifestations noted over 10 to 20 years for two of these patients were chylothorax (n = 1), erysipelas (n = 1), and gradual-onset nonchylous scrotal lymphorrhea (n = 1). Targeted endovascular lymphatic disruption via sclerosis, embolization, or ablation (n = 8) results were mixed depending on the degree of central lymphatic involvement and included resolution of symptoms (n = 1), postoperative abdominal hemorrhage (n = 1), stable condition or minor improvement (n = 5), and death (n = 2). Large lymphatic vessel ligation or accidental incision (n = 6) occurred during thoracotomy (n = 4), scrotoplasty (n = 1), or inguinal lymph node biopsy (n = 1). These resulted in postoperative onset of new-onset regional lymphatic reflux (n = 5), chylothorax (n = 4), death (n = 3), or persistent or unchanged symptoms (n = 1).

CONCLUSIONS

Imaging of the central lymphatics enabled characterization of lymphatic developmental features and guided operative management of lymphatic vascular defects in patients with NS. This review of the literature suggests that the surgical preservation or enhancement of central lymphatic return in patients with NS may improve interventional outcomes, whereas the disruption of central lymph flow has significant potential to cause severe postoperative complications and worsening of the patient's clinical condition.

HUMAN CHROMOSOME MAP OF LYMPHEDEMA-LYMPHANGIOGENESIS GENES: TEMPLATE FOR CURRENT AND FUTURE DISCOVERY

We have created a human chromosomal map of the location of known and candidate genes involved in primary lymphedema (PLE). This should facilitate further discovery and provide a basis for understanding microdeletions which cause lymphedema.

Lack of embryonic homozygous or adult heterozygous lymphatic phenotypes for a Sos1 mutation and lack of lymphatic embryonic phenotypes for a homozygous Cx47 mutation in mice

We have studied the lymphatic phenotypes of 2 mutations, known to cause abnormalities of lymphatics in humans, in mice. The Cx47 R260C mutation (variably penetrant in humans heterozygous for it and causing limb lymphedema) had an adult mouse phenotype of hyperplasia and increased lymph nodes only in homozygous condition but we did not find any anatomical phenotype in day 16.5 homozygous embryos. Mice harboring the Sos1 mutation E846K (causing Noonan's in man which occasionally shows lymphatic dysplasia) had no adult heterozygous phenotype in lymphatic vessel appearance and drainage (homozygotes are early embryonic lethals) while day 16.5 heterozygous embryos also had no detectable anatomical phenotype.

Centrifugal Versus Centripetal Origin(s) of the Lymphatic System: Controversy (Mostly) Resolved?

New findings reopen the controversy about centrifugal vs. centripetal origin of the lymphatic system and support that the latter may be the predominant source of lymphatic endothelial cells from mesenchymal lymphangioblasts.

Primary lymphoedema

Lymphoedema is the swelling of one or several parts of the body owing to lymph accumulation in the extracellular space. It is often chronic, worsens if untreated, predisposes to infections and causes an important reduction in quality of life. Primary lymphoedema (PLE) is thought to result from abnormal development and/or functioning of the lymphatic system, can present in isolation or as part of a syndrome, and can be present at birth or develop later in life. Mutations in numerous genes involved in the initial formation of lymphatic vessels (including valves) as well as in the growth and expansion of the lymphatic system and associated pathways have been identified in syndromic and non-syndromic forms of PLE. Thus, the current hypothesis is that most cases of PLE have a genetic origin, although a causative mutation is identified in only about one-third of affected individuals. Diagnosis relies on clinical presentation, imaging of the structure and functionality of the lymphatics, and in genetic analyses. Management aims at reducing or preventing swelling by compression therapy (with manual drainage, exercise and compressive garments) and, in carefully selected cases, by various surgical techniques. Individuals with PLE often have a reduced quality of life owing to the psychosocial and lifelong management burden associated with their chronic condition. Improved understanding of the underlying genetic origins of PLE will translate into more accurate diagnosis and prognosis and personalized treatment.

Research Priorities in Lymphatic Interventions: Recommendations from a Multidisciplinary Research Consensus Panel

Recognizing the increasing importance of lymphatic interventions, the Society of Interventional Radiology Foundation brought together a multidisciplinary group of key opinion leaders in lymphatic medicine to define the priorities in lymphatic research. On February 21, 2020, SIRF convened a multidisciplinary Research Consensus Panel (RCP) of experts in the lymphatic field. During the meeting, the panel and audience discussed potential future research priorities. The panelists ranked the discussed research priorities based on clinical relevance, overall impact, and technical feasibility. The following research topics were prioritized by RCP: lymphatic decompression in patients with congestive heart failure, detoxification of thoracic duct lymph in acute illness, development of newer agents for lymphatic imaging, characterization of organ-based lymph composition, and development of lymphatic interventions to treat ascites in liver cirrhosis. The RCP priorities underscored that the lymphatic system plays an important role not only in the intrinsic lymphatic diseases but in conditions that traditionally are not considered to be lymphatic such as congestive heart failure, liver cirrhosis, and critical illness. The advancement of the research in these areas will lead the field of lymphatic interventions to the next level.

EDITORIAL: SARS-CoV-2/COVID-19, LYMPHATIC VESSELS, LYMPH, AND LYMPHOLOGY

Lymphatic vessels and lymph are a missing link in SARS-CoV-2/COVID-19 pathophysiology and therapeutic strategies. Based on well-established principles of lymphatic function and dysfunction and a neglected literature, this article highlights promising directions for future research and clinical exploration.

NON-CONTRAST MR LYMPHOGRAPHY OF RARE LYMPHATIC ABNORMALITIES

Detailed imaging of the lymphatic system often requires direct injection of contrast into lymph nodes which can be technically challenging, time consuming, and produce painful stimuli. We sought to describe the use of non-contrast MR lymphography (NCMRL) for normal controls and patients with a variety of rare disorders associated with lymphatic pathologies. Two control subjects and five affected patients (decompensated Fontan circulation, central conducting lymphatic abnormality, familial lymphedema and two with Gorham-Stout disease) were studied. NCMRL images were segmented in a semi-automated fashion and the major lymphatic channels and thoracic duct (TD) highlighted for identification. Adequate imaging was available for both controls and 4/5 affected patients; the youngest patient could not be imaged given patient motion. For the two controls, the TD was seen in the expected anatomic location. For the decompensated Fontan patient, there were numerous tortuous lymphatic channels, predominantly in the upper chest and neck. For the familial lymphedema patient, a TD was not identified; instead, peripheral lymphatic collaterals near the lateral chest walls. For the first Gorham-Stout patient, the TD was enlarged with large intrathoracic lymph collections. For the second Gorham-Stout patient, there were bilateral TD with lymph collections in vertebral bodies. Using NCMRL, we were able to image normal and abnormal lymphatic systems. An important learning point is the potential need for sedation for younger patients due to long image acquisition times and fine resolution of the structures of interest.

Human chromosome map of lymphedema-lymphangiogenesis genes: Template for current and future discovery

We have created a human chromosomal map of the location of known and candidate genes involved in primary lymphedema (PLE). This should facilitate further discovery and provide a basis for understanding microdeletions which cause lymphedema.

Imaging of lymphatic dysplasia in Noonan syndrome: Case studies and historical atlas

To determine the historical use and utility of various lymphatic imaging modalities in Noonan syndrome (NS) patients, we performed a comprehensive literature review by collecting the published medical imaging of NS lymphatic dysplasias. We correlated imaging findings with clinical phenotypes and treatment. Our analysis of lymphatic imaging modalities provides an algorithmic approach to imaging and patient care across the spectrum of NS developmental defects. A total of 54 NS cases have been published since 1975. Using the observations reported in 15 reviewed publications, an association was made between disruptions in central lymphatic flow and poor clinical presentations/outcomes in NS patients.

Abnormal lymphatic phenotype in a CRISPR mouse model of the human lymphedema-causing Connexin47 R260C point mutation

Connexin proteins form gap junctions controlling exchange of ions and small molecules between cells and play an important role in movement of lymph within lymphatic vessels. Connexin47 (CX47) is highly expressed in lymphatic endothelial cells and CX47 missense mutations, i.e., R260C, cosegregate with primary lymphedema in humans. However, studies utilizing CX47 knockout mice have failed to demonstrate any lymphatic anomalies. To unravel the lymphatic consequences of expressing a mutant CX47 protein, we used CRISPR technology to create a mouse carrying a Cx47 missense mutation (Cx47R259C) equivalent to the human CX47R260C missense mutation associated with human primary lymphedema. Intradermal Evans Blue dye injection identified a 2-fold increase in regional lymph nodes in homozygous Cx47R259C mice compared to wildtype, particularly in the jugular region (4.8 ± 0.4 and 2.0 ± 0.0, respectively, p<0.01). Associated lymphatic channels were increased in Cx47R259C mice and mesenteric lymph reflux occurred in homozygous Cx47R259C mice but not in wildtype. Contractility of superficial cervical lymphatics, assessed by pressure myography, was reduced in homozygous Cx47R259C mice compared to wildtype. In conclusion, our data are the first to demonstrate a role for the Cx47 protein in lymphatic anatomy and function. This phenotype is similar to that found with other valve deficient mouse mutants, e.g., in Foxc2. Of significance, this study is the first to use CRISPR technology to develop a pre-clinical model of primary lymphedema and demonstrates the importance of distinguishing between lack of and presence of mutant protein when developing clinically relevant animal models for translation of pre-clinical findings.

EDITORIAL: THORACIC DUCT DECOMPRESSION: AN IDEA WHOSE TIME HAS COME – AGAIN

Thoracic duct decompression (TDD) is an idea first proposed and applied as a novel therapeutic strategy by lymphologists in the 1960's. TDD is recently being reexamined and, in selected patients with portal hypertension from hepatic cirrhosis or with central venous hypertension from isolated right-sided heart failure, undertaken using advanced surgical and image-guided interventional radiologic approaches.

Lymphatic Imaging: Current Noninvasive and Invasive Techniques

After nearly disappearing, invasive lymphangiography not only has resurged, but new approaches have been developed to guide lymphatic interventions. At the same time, noninvasive lymphatic imaging is playing a larger role in the evaluation of lymphatic pathologies. Lymphangioscintigraphy, computed tomography lymphangiography, and magnetic resonance lymphangiography are increasingly being used as alternatives to invasive diagnostic lymphangiography. The purpose of this article is to review current invasive and noninvasive lymphatic imaging techniques.

EDITORIAL

EVOLUTION OF THE 2020 INTERNATIONAL SOCIETY OF LYMPHOLOGY CONSENSUS DOCUMENT PARALLELS ADVANCES IN LYMPHOLOGY: AN HISTORICAL PERSPECTIVE

CONGENITAL CHYLOTHORAX: CURRENT EVIDENCE-BASED PRENATAL AND POST-NATAL DIAGNOSIS AND MANAGEMENT

Congenital chylothorax is an uncommon condition but represents the main cause of congenital pleural effusion during the neonatal period. It usually appears before birth, both as an isolated disorder or in association with hydrops fetalis, negatively affecting the subsequent neonatal outcome. Prenatal treatment is usually considered to ensure a satisfactory lung development in case of moderate to severe pleural effusion or in the presence of hydrops, although consensus on treatment timing and modalities has not been reached to date. Both medical and surgical therapeutic strategies are available to treat this condition and novel treatment options have been recently attempted with acceptable results in both prenatal and post-natal setting. The heterogeneous clinical presentation of congenital chylothorax together with its rarity, its numerous etiologies and the absence of a highly effective treatment renders the diagnostic and therapeutic approach difficult to standardize. In addition, adequate visualization of the lymphatic system is complex, especially in small neonates, although new promising techniques have been developed lately and may contribute to improved management of this serious but infrequent condition. This review focuses on the current evidence base for the diagnosis and treatment options for congenital chylothorax, suggesting a rational diagnostic and therapeutic approach both in the prenatal and in the neonatal period.

EVOLUTION OF THE 2020 INTERNATIONAL SOCIETY OF LYMPHOLOGY CONSENSUS DOCUMENT PARALLELS ADVANCES IN LYMPHOLOGY: AN HISTORICAL PERSPECTIVE

[Editorial] Evolution of the 2020 international society of lymphology consensus document parallels advances in lymphology: An historical perspective.

SARS-CoV-2/COVID-19, Lymphatic vessels, lymph, and lymphology

[Editorial] Lymphatic vessels and lymph are a missing link in SARS-CoV-2/COVID-19 pathophysiology and therapeutic strategies. Based on well-established principles of lymphatic function and dysfunction and a neglected literature, this article highlights promising directions for future research and clinical exploration.

Non-contrast MR lymphography of rare lymphatic abnormalities

Detailed imaging of the lymphatic system often requires direct injection of contrast into lymph nodes which can be technically challenging, time consuming, and produce painful stimuli. We sought to describe the use of non-contrast MR lymphography (NCMRL) for normal controls and patients with a variety of rare disorders associated with lymphatic pathologies. Two control subjects and five affected patients (decompensated Fontan circulation, central conducting lymphatic abnormality, familial lymphedema and two with Gorham-Stout disease) were studied. NCMRL images were segmented in a semiautomated fashion and the major lymphatic channels and thoracic duct (TD) highlighted for identification. Adequate imaging was available for both controls and 4/5 affected patients; the youngest patient could not be imaged given patient motion. For the two controls, the TD was seen in the expected anatomic location. For the decompensated Fontan patient, there were numerous tortuous lymphatic channels, predominantly in the upper chest and neck. For the familial lymphedema patient, a TD was not identified; instead, peripheral lymphatic collaterals near the lateral chest walls. For the first Gorham- Stout patient, the TD was enlarged with large intrathoracic lymph collections. For the second Gorham-Stout patient, there were bilateral TD with lymph collections in vertebral bodies. Using NCMRL, we were able to image normal and abnormal lymphatic systems. An important learning point is the potential need for sedation for younger patients due to long image acquisition times and fine resolution of the structures of interest.

Thoracic duct decompression: An idea whose time has come - again

[Editorial] Thoracic duct decompression (TDD) is an idea first proposed and applied as a novel therapeutic strategy by lymphologists in the 1960's. TDD is recently being reexamined and, in selected patients with portal hypertension from hepatic cirrhosis or with central venous hypertension from isolated right-sided heart failure, undertaken using advanced surgical and image-guided interventional radiologic approaches.

Role of Lymphatic Deficiency in the Pathogenesis and Progression of Inflammatory Bowel Disease to Colorectal Cancer in an Experimental Mouse Model

BACKGROUND

Inflammatory bowel disease (IBD) is characterized by chronic inflammation, which can progress to colorectal cancer, with duration of disease being the most important risk factor. Although many factors are involved, the pathogenic link between inflammation and cancer and the role played by the lymphatic system have not been fully investigated. This project uses lymphatic-deficient mice (Angiopoietin-2 [Ang2] knockout) to examine the lymphatic system in the progression of IBD to colorectal cancer.

METHODS

Angiopoietin-2 wild-type, heterozygote, and knockout mice received a single injection of the procarcinogen azoxymethane and had an IBD-promoting chemical irritant (dextran sodium sulfate) added to their drinking water over a 7-week period. We measured disease activity (weight loss, stool consistency, fecal occult blood) during the study and at sacrifice, collected blood for cytokine/biomarker (Ang2, interleukin [IL] 1-β, IL-6, tumor necrosis factor α [TNFα], and VEGF-C) enzyme-linked immunosorbent assay analysis, measured colon length, and assessed tumor burden.

RESULTS

Ang2 knockout (KO) mice exhibited reduced (55%) survival vs wild-type (100%) and heterozygotes (91%; P < 0.01 and P < 0.0001, respectively). Most (>89%) mice developed tumors, and the incidence of colorectal cancer did not differ among the genotypes (P = 0.32). The tumor area was significantly increased in KO mice (P = 0.004). Of the biomarkers measured in the serum, Ang2 and TNF-α concentrations were significantly different among the genotypes (P = 3.35e-08 and P = 0.003 respectively). Disease activity was significantly increased in KO mice compared with wild-type and heterozygote mice (P = 0.033).

CONCLUSIONS

Lymphatic deficiency, defective lymphangiogenesis, and impaired lymphatic-generated inflammation did not protect against clinical IBD or progression to colorectal cancer in this experimental model.

Resolution of Protein-Losing Enteropathy after Congenital Heart Disease Repair by Selective Lymphatic Embolization

With improving survival of children with complex congenital heart disease (CCHD), postoperative complications, like protein-losing enteropathy (PLE) are increasingly encountered. A 3-year-old girl with surgically corrected CCHD (ventricular inversion/L-transposition of the great arteries, ventricular septal defect, pulmonary atresia, post-double switch procedure [Rastelli and Glenn]) developed chylothoraces. She was treated with pleurodesis, thoracic duct ligation and subsequently developed chylous ascites and PLE (serum albumin ≤0.9 g/dL) and was malnourished, despite nutritional rehabilitation. Lymphangioscintigraphy/single-photon emission computed tomography showed lymphatic obstruction at the cisterna chyli level. A segmental chyle leak and chylous lymphangiectasia were confirmed by gastrointestinal endoscopy, magnetic resonance (MR) enterography, and MR lymphangiography. Selective glue embolization of leaking intestinal lymphatic trunks led to prompt reversal of PLE. Serum albumin level and weight gain markedly improved and have been maintained for over 3 years. Selective interventional embolization reversed this devastating lymphatic complication of surgically corrected CCHD.

EARLY FETAL HYDROPIC CHANGES ARE ASSOCIATED WITH MODERATE DILATATION OF THE BRAIN VENTRICULAR SYSTEM: A CLUE TO A POSSIBLE LINK BETWEEN CERVICAL LYMPHATIC ENGORGEMENT AND VENTRICULAR DILATATION?

The aim of this study is to assess whether early cervical lymphatic obstruction is associated with a sonographically detectable dilatation of the ventricular system in the 1st trimester of pregnancy. In particular, the objective is to assess whether fetuses with non-immune hydrops fetalis (NIHF), cystic hygroma, or enlarged nuchal translucency (NT) have a greater atrial width/biparietal diameter (AW/BPD) ratio than normal at time of the combined first trimester screening scan. This retrospective study included 96 first trimester fetuses (33 normal and 63 with various degree of cervical lymphatic engorgement). Inclusion criteria were CRL in the 45-84 mm range and availability of one or more three-dimensional volume datasets of the fetal head, acquired from the BPD plane. Each three-dimensional volume dataset was opened and multiplanar correlation employed to align the three orthogonal planes. The ratio between the atrial width and the BPD (AW/BPD ratio) was used to evaluate the possible presence of increased amount of cerebrospinal fluid. Abnormal cases were placed into 4 categories: 1)enlarged non-septated NT 2.5-3.9 mm, no hydrops; 2) grossly enlarged non-septated NT/ edema &gt;3.9 mm; 3) cystic hygroma and/or NIHF; 4) major anomalies with NT &lt;2.5 mm. Presence of dilatation of the latero-cervical jugular lymphatic sacs, karyotype and presence of congenital anomalies were also recorded. The One-way ANOVA test was used to compare means. Intra- and inter-observer variability were also assessed. The AW/BPD ratio was found to be significantly higher in fetuses with grossly enlarged NT/nuchal edema and NIHF/septated cystic hygroma than in normal (p &lt;0.05 and p &lt;0.01, respectively). Also, the AW/BPD ratio was significantly higher in NIHF/septated cystic hygroma than in enlarged NT 2.5-3.9 mm (p &lt;0.05). In case of enlarged NT (2.5-3.9 mm), the AW/BPD ratio is significantly higher in presence of JLS (p &lt;0.01). At the end of the first trimester, presence of cervical lymphatic engorgement, in terms of grossly enlarged NT, nuchaledema, septated cystic hygroma, and NIHF, is statistically associated with a moderate dilatation of the ventricular system. Of note, among fetuses with moderately enlarged NT, those with evidence of dilatation of the JLS show a statistically significant increase in the AW/BPD ratio.

Antivenom effect on lymphatic absorption and pharmacokinetics of coral snake venom using a large animal model

Context: Historically, administration and dosing of antivenom (AV) have been guided primarily by physician judgment because of incomplete understanding of the envenomation process. As demonstrated previously, lymphatic absorption plays a major role in the availability and pharmacokinetics (PK) of coral snake venom injected subcutaneously, which suggests that absorption from subcutaneous tissue is the limiting step for venom bioavailability, supporting the notion that the bite site is an ongoing venom depot. This feature may underlie the recurrence phenomena reported in viperid envenomation that appear to result from a mismatch between venom and AV PK. The role of lymphatic absorption in neutralization of venom by AV administered intravenously remains unclear. Methods: The effect of AV on systemic bioavailability and neutralization of Micrurus fulvius venom was assessed using a central lymph-cannulated sheep model. Venom was administered by subcutaneous injection in eight sheep, four with and four without thoracic duct cannulation and drainage. Two hours after venom injection, AV was administered intravenously. Venom and AV concentrations in serum and lymph were determined by ELISA assay from samples collected over a 6-h period and in tissues harvested post-mortem. Results: After AV injection, venom levels in serum fell immediately to undetectable with a subsequent increase in concentration attributable to non-toxic venom proteins. In lymph, AV became detectable 6 min after treatment; venom levels dropped concurrently but remained detectable 4 h later. Post-mortem samples from the venom injection site confirmed the presence of venom near the point of injection. Neither venom nor AV was detected at significant concentrations in major organs or contralateral skin. Conclusions: Intravenous AV immediately neutralizes venom in the bloodstream and can extravasate to neutralize venom absorbed by lymph but this neutralization seems to be slow and incomplete. Residual venom in the inoculation site demonstrates that this site functions as a depot where it is not neutralized by AV, which allows the venom to remain active with slow delivery to the bloodstream for ongoing systemic distribution.

Early fetal hydropic changes are associated with moderate dilatation of the brain ventricular system: A clue to a possible link between cervical lymphatic engorgement and ventricular dilatation?

The aim of this study is to assess whether early cervical lymphatic obstruction is associated with a sonographically detectable dilatation of the ventricular system in the 1st trimester of pregnancy. In particular, the objective is to assess whether fetuses with non-immune hydrops fetalis (NIHF), cystic hygroma, or enlarged nuchal translucency (NT) have a greater atrial width/biparietal diameter (AW/BPD) ratio than normal at time of the combined first trimester screening scan. This retrospective study included 96 first trimester fetuses (33 normal and 63 with various degree of cervical lymphatic engorgement). Inclusion criteria were CRL in the 45-84 mm range and availability of one or more three-dimensional volume datasets of the fetal head, acquired from the BPD plane. Each three-dimensional volume dataset was opened and multiplanar correlation employed to align the three orthogonal planes. The ratio between the atrial width and the BPD (AW/BPD ratio) was used to evaluate the possible presence of increased amount of cerebrospinal fluid. Abnormal cases were placed into 4 categories: 1) enlarged non-septated NT 2.5-3.9 mm, no hydrops; 2) grossly enlarged non-septated NT / edema >3.9 mm; 3) cystic hygroma and/ or NIHF; 4) major anomalies with NT <2.5 mm. Presence of dilatation of the laterocervical jugular lymphatic sacs, karyotype and presence of congenital anomalies were also recorded. The One-way ANOVA test was used to compare means. Intra- and inter-observer variability were also assessed. The AW/BPD ratio was found to be significantly higher in fetuses with grossly enlarged NT/nuchal edema and NIHF/septated cystic hygroma than in normal (p <0.05 and p <0.01, respectively). Also, the AW/BPD ratio was significantly higher in NIHF/septated cystic hygroma than in enlarged NT 2.5-3.9 mm (p <0.05). In case of enlarged NT (2.5-3.9 mm), the AW/BPD ratio is significantly higher in presence of JLS (p <0.01). At the end of the first trimester, presence of cervical lymphatic engorgement, in terms of grossly enlarged NT, nuchal edema, septated cystic hygroma, and NIHF, is statistically associated with a moderate dilatation of the ventricular system. Of note, among fetuses with moderately enlarged NT, those with evidence of dilatation of the JLS show a statistically significant increase in the AW/BPD ratio.

Whole-body lymphangioscintigraphy and SPECT/CT in children with lymphatic complications after surgery for complex congenital heart disease

The number of patients surviving repair of complex congenital heart disease (CCHD) has increased due to improved surgical techniques, post operative management and outpatient care. Likewise, this growing patient population has demonstrated an increasing number and complexity of complications involving the lymphatic system. To evaluate the peripheral and central lymphatic system, whole-body lymphangioscintigraphy (LAS) is considered as the initial imaging evaluation of choice. To date, very few publications exist on the value of lymphatic imaging techniques in infants and small children with lymphatic complications following surgery for congenital heart disease. A retrospective review of medical records from 2008 to 2018 was performed for pediatric patients referred for lymphatic complications after CCHD surgery at an academic medical center. LAS and SPECT/CT was performed using intradermal bipedal injections of Tc 99m labeled filtered sulfur colloid, and in some patients also bilateral hand injections, followed by dynamic imaging and whole- body planar imaging typically up to 180 minutes post injection. Clinical decision making and outcomes were recorded. LAS and SPECT/CT were performed without complication in pediatric patients with prior surgery for CCHD. LAS successfully localized various lymphatic abnormalities such as lymphatic obstruction, reflux, and leaks, which were further delineated by SPECT/CT. LAS findings directed further evaluation with more definitive studies, management and prognosis. Five of the ten patients had follow up outcome data - 2 years and up to 10 years. LAS and SPECT/CT are safe and effective techniques for the initial evaluation of lymphatic abnormalities in pediatric patients with CCHD. LAS, particularly with further 3D localization by SPECT/CT, provides functional imaging of peripheral and central lymphatic flow and thus provides guidance for medical therapy, non operative interventional management, and surgical therapy for these diverse, debilitating, and often life threatening disorders.

Congenital chylothorax: Current evidence-based prenatal and post-natal diagnosis and management

Congenital chylothorax is an uncommon condition but represents the main cause of congenital pleural effusion during the neonatal period. It usually appears before birth, both as an isolated disorder or in association with hydrops fetalis, negatively affecting the subsequent neonatal outcome. Prenatal treatment is usually considered to ensure a satisfactory lung development in case of moderate to severe pleural effusion or in the presence of hydrops, although consensus on treatment timing and modalities has not been reached to date. Both medical and surgical therapeutic strategies are available to treat this condition and novel treatment options have been recently attempted with acceptable results in both prenatal and post-natal setting. The heterogeneous clinical presentation of congenital chylothorax together with its rarity, its numerous etiologies and the absence of a highly effective treatment renders the diagnostic and therapeutic approach difficult to standardize. In addition, adequate visualization of the lymphatic system is complex, especially in small neonates, although new promising techniques have been developed lately and may contribute to improved management of this serious but infrequent condition. This review focuses on the current evidence base for the diagnosis and treatment options for congenital chylothorax, suggesting a rational diagnostic and therapeutic approach both in the prenatal and in the neonatal period.

From childhood onset lymphedema to fatal fetal hydrops: Possible modifying genes for a FOXC2 mutation

We performed whole exome sequencing in a family with FOXC2 mutation where the phenotype in one generation was strikingly more severe. Although there were 3 mutations shared by 2 fatal fetal hydrops cases and not the mildly affected mother, none of them were likely to be the cause of the marked phenotypic change.

In Memoriam Prof. Prof. h.c. Dr. med. Michael Földi, January 10, 1920 - October 20, 2018 "Father of Lymphology"

In Memoriam: With deep sadness the world of Lymphology learned of the death of Prof. Prof. h.c. Dr. med. Michael Földi, a ground breaking pioneer of modern Lymphology. Words alone will never fully describe or capture the breadth and depth of Michael's contribution to our lymphatic knowledge and the legacy he has left for us all.

Brain lymphatic drainage system in fetus and newborn: Birth of a new era of exploration

A peculiar brain lymphatic drainage system has been recently fully recognized in animals and humans. It comprises different draining pathways, including the lymphatic system, the perivascular drainage pathway, and the cerebrospinal fluid (CSF) drainage routes. Although scant data are available about its function during the neonatal period, it may play a role in neonatal brain diseases. In this review, we focus on the actual knowledge of brain lymphatic drainage system, and we hypothesize potential implications of its impairment and dysfunction in major neonatal neurological diseases.

Lymphangioleiomyomatosis and Gorham-Stout disease: Primary or secondary disorders of the lymphatic system?

Lymphangioleimyomatosis and Gorham- Stout disease, rare disorders which share features of proliferating lymphatic vessels, predominantly in the lung in the former and bone in the latter, commonly manifest as progressive lung disease often associated with life-threatening complications of chylous reflux from central lymphatic obstruction/ leakage. This Lymphspiration-Editorial proposes that, rather than a secondary complication, lymphatic obstruction/ dysfunction is a much earlier or even the primary event in the pathogenesis of both disorders and that lymphostasis drives the cellular proliferative response in both lung and bone and even distant sites.

Neonatal Lymphedema from Thoracic Duct Obstruction Complicating Percutaneous Intravenous Central Catheterization

Percutaneous intravenous central catheter (PICC) complications are not common and generalized edema and anasarca in neonates as a complication of PICC malposition is even rarer. Documentation of the pathomechanisms of lymphedema in cases of severe anasarca in neonates is not often done. Here we document thoracic duct obstruction as the cause of lymphedema in a neonate with severe nonpitting generalized edema. Most PICC procedures should ideally be guided by point-of-care bedside ultrasound (US), and this precaution may prevent malposition of PICC lines although it will not detect subsequent migration or extravasation.

Proposal for Prevention or Alleviation of Protein/Lymph-Losing Enteropathy (PLE/LLE) After Fontan Circulation Treatment of Univentricular Hearts: Restoration of Lymph Balance With a "Lymphatic Right-to-Left Shunt."

In Fontan circulations created for univentricular hearts, systemic venous return is diverted to the lungs before returning to the heart. The Total Cavopulmonary Connection (TCPC) is often the preferred surgical procedure whereby a 4-way anastomosis is created with inflow from the superior vena cava (SVC) and inferior vena cava (IVC) and outflow to the right and left branches of the pulmonary artery. In this arrangement, the systemic venous pressure must be elevated sufficiently to perfuse the lungs passively without the normal boost of the right ventricle. Hence, unlike surgical corrections for other congenital heart conditions, the systemic venous pressures in a Fontan circuit must be elevated to make the circulation work. It is proposed here that the incidence of PLE/LLE is directly related to elevated venous and lymphatic pressures, which cause leakage of proteins/lymph into the gastrointestinal tract (GIT) and expulsion from the body. It is commonly held that elevated venous pressures are relatively better tolerated in the upper body, but much less so in the heptatosplanchnic circulation and the lower body. It is also well established that elevated venous pressure increases lymph formation, most of which is produced in the hepatosplanchnic region (liver and intestine). It is further argued here that the increase in lymph filling pressure arising from the higher lymph flow, in association with the backpressure exerted by elevated venous pressure at the main drainage point into the venous system, results in a substantial increase in pressure in the thoracic duct. This pressure is transmitted back to the intestinal lymphatics, causing dilatation with lacteal rupture and protein or bulk lymph leakage into the intestine. We propose in this paper a new approach, based on experimental evidence, to prevent and/or alleviate this condition by draining or redirecting the thoracic duct (or, alternatively, a more localized intestinal lymphatic vessel) into one of the pulmonary veins or the left atrium, which are typically at near-normal pressure in a Fontan circulation. This “lymphatic-venous right-to-left” shunt maneuver would significantly reduce the venous backpressure on the lymphatics as well as improve lymph circulation, resulting in a decrease in the intestinal lymphatic pressure and thereby prevent or alleviate protein/lymph loss, i.e. lymph balance would be restored. Moreover, the greatly facilitated lymphatic flow would encourage further capillary filtration to relieve excessive venous pressure in the hepatosplanchnic region and protect the liver and kidneys. This paper is intended as a discussion document for elicitation of comments on the soundness and viability of this proposal as well as on technical challenges and steps to explore and advance it.

Characterization of TCP-1 probes for molecular imaging of colon cancer

Molecular probes capable of detecting colorectal cancer (CRC) are needed for early CRC diagnosis. The objective of this study was to characterize c[CTPSPFSHC]OH (TCP-1), a small peptide derived from phage display selection, for targeting human CRC xenografts using technetium-99m ((99m)Tc)-labeled TCP-1 and fluorescent cyanine-7 (Cy7)-labeled form of the peptide (Cy7-TCP-1). (99m)Tc-TCP-1 was generated by modifying TCP-1 with succinimidyl-6-hydrazino-nicotinamide (S-HYNIC) followed by radiolabeling. In vitro saturation binding experiments were performed for (99m)Tc-TCP-1 in human HCT116 colon cancer cells. SCID mice with human HCT116 cancer xenografts were imaged with (99m)Tc-TCP-1 or control peptide using a small-animal SPECT imager: Group I (n=5) received no blockade; Group II (n=5) received a blocking dose of non-radiolabeled TCP-1. Group III (n=5) were imaged with (99m)Tc-labeled control peptide (inactive peptide). SCID mice with human PC3 prostate cancer xenografts (Group IV, n=5) were also imaged with (99m)Tc-TCP-1. Eight additional SCID mice bearing HCT116 xenografts in dorsal skinfold window chambers (DSWC) were imaged by direct positron imaging of (18)F-fluorodeoxyglucose ((18)F-FDG) and fluorescence microscopy of Cy7-TCP-1. In vitro(99m)Tc-HYNIC-TCP-1 binding assays on HCT 116 cells indicated a mean Kd of 3.04±0.52nM. In cancer xenografts, (99m)Tc-TCP-1 radioactivity (%ID/g) was 1.01±0.15 in the absence of blockade and was reduced to 0.26±0.04 (P<0.01) with blockade. No radioactive uptake was observed in the PC3 tumors with (99m)Tc-TCP-1 or HCT116 tumors with inactive peptide. Cy7-TCP-1 activity localized not only in metabolically active tumors, as defined by (18)F-FDG imaging, but also in peritumoral microvasculature. In conclusion, TCP-1 probes may have a distinct targeting mechanism with high selectivity for CRC and tumor-associated vasculature. Molecular imaging with TCP-1 probes appears promising to detect malignant colorectal lesions.

Segregated Foxc2, NFATc1 and Connexin expression at normal developing venous valves, and Connexin-specific differences in the valve phenotypes of Cx37, Cx43, and Cx47 knockout mice

Venous valves (VVs) are critical for unidirectional blood flow from superficial and deep veins towards the heart. Congenital valve aplasia or agenesis may, in some cases, be a direct cause of vascular disease, motivating an understanding of the molecular mechanisms underlying the development and maintenance of VVs. Three gap junction proteins (Connexins), Cx37, Cx43, and Cx47, are specifically expressed at VVs in a highly polarized fashion. VVs are absent from adult mice lacking Cx37; however it is not known if Cx37 is required for the initial formation of valves. In addition, the requirement of Cx43 and Cx47 for VV development has not been studied. Here, we provide a detailed description of Cx37, Cx43, and Cx47 expression during mouse vein development and show by gene knockout that each Cx is necessary for normal valve development. The valve phenotypes in the knockout lines exhibit Cx-specific differences, however, including whether peripheral or central VVs are affected by gene inactivation. In addition, we show that a Cx47 null mutation impairs peripheral VV development but does not affect lymphatic valve formation, a finding of significance for understanding how some CX47 mutations cause inherited lymphedema in humans. Finally, we demonstrate a striking segregation of Foxc2 and NFATc1 transcription factor expression between the downstream and upstream faces, respectively, of developing VV leaflets and show that this segregation is closely associated with the highly polarized expression of Cx37, Cx43, and Cx47. The partition of Foxc2 and NFATc1 expression at VV leaflets makes it unlikely that these factors directly cooperate during the leaflet elongation stage of VV development.

Combining Foxc2 and Connexin37 deletions in mice leads to severe defects in lymphatic vascular growth and remodeling

Connexins (Cxs), proteins that are vital for intercellular communication in vertebrates, have recently been shown to play a critical role in lymphatic development. However, our knowledge is currently limited regarding the functional relationships of Cxs with other proteins and signaling pathways. Cell culture studies have shown that Cx37 is necessary for coordinated activation of the transcription factor NFATc1, which cooperates with Foxc2 (another transcription factor) during lymphatic endothelial development. These data suggest that Cxs, Foxc2, and NFATc1 are part of a common developmental pathway. Here, we present a detailed characterization of Foxc2(+/-)Cx37(-/-) mice, demonstrating that lymphatic network architecture and valve formation rely on the concurrent embryonic expression and function of Foxc2 and Cx37. Foxc2(+/-)Cx37(-/-) mice have lymphedema in utero, exhibit craniofacial abnormalities, show severe dilation of intestinal lymphatics, display abnormal lacteal development, lack lymphatic valves, and typically die perinatally (outcomes not seen in Foxc2(+/-) or Cx37(-/-) mice separately). We provide a rigorous, quantitative documentation of lymphatic vascular network changes that highlight the specific structural alterations that occur in Foxc2(+/-)Cx37(-/-) mice. These data provide further evidence suggesting that Foxc2 and Cx37 are elements in a common molecular pathway directing lymphangiogenesis.

Curcuminoids limit neutrophil-mediated reperfusion injury in experimental stroke by targeting the endothelium

OBJECTIVE

We sought to test the hypothesis that turmeric-derived curcuminoids limit reperfusion brain injury in an experimental model of stroke via blockade of early microvascular inflammation during reperfusion.

METHODS

Male Sprague Dawley rats subjected to MCAO/R were treated with turmeric-derived curcuminoids (vs. vehicle) 1 hour prior to reperfusion (300 mg/kg ip). Neutrophil adhesion to the cerebral microcirculation and measures of neutrophil and endothelial activation were assayed during early reperfusion (0-4 hours); cerebral infarct size, edema, and neurological function were assessed at 24 hours. Curcuminoid effects on TNFα-stimulated human brain microvascular endothelial cell (HBMVEC) were assessed.

RESULTS

Early during reperfusion following MCAO, curcuminoid treatment decreased neutrophil rolling and adhesion to the cerebrovascular endothelium by 76% and 67% and prevented >50% of the fall in shear rate. The increased number and activation state (CD11b and ROS) of neutrophils were unchanged by curcuminoid treatment, while increased cerebral expression of TNFα and ICAM-1, a marker of endothelial activation, were blocked by >30%. Curcuminoids inhibited NF-κB activation and subsequent ICAM-1 gene expression in HBMVEC.

CONCLUSION

Turmeric-derived curcuminoids limit reperfusion injury in stroke by preventing neutrophil adhesion to the cerebrovascular microcirculation and improving shear rate by targeting the endothelium.

A novel FLT4 mutation identified in a patient with Milroy disease

Milroy disease is an autosomal dominant disorder generally presenting with below the knee lymphedema at birth. It is linked to mutations in the tyrosine kinase domain of the VEGFR3 protein which is encoded in the FLT4 gene. Here we report a case of Milroy disease in a patient with a dominant pattern of inheritance, classical physical findings, and lymphatic system imaging demonstrating lack of tracer transport in the lower limbs. Genetic analysis revealed a novel missense mutation compared to a summary of reported mutations causing Milroy Disease.

Lymphoscintigraphy in plastic bronchitis, a pediatric case report

Plastic bronchitis (PB) is an uncommon, potentially fatal disease, marked by endobronchial cast formation causing variable degrees of respiratory distress. Primary and secondary pulmonary lymphatic abnormalities have been identified among the underlying mechanisms of cast formation. We present a case of PB where lymphoscintigraphy demonstrated the underlying lymphatic defect. A 6-year-old Hispanic male with congenital heart disease (CHD; post-Fontan) presented with recurrent pneumonia, respiratory distress. Bronchoscopy showed inflamed hypervascular mucosa and thick mucus plugs; no casts were seen. Later, PB was diagnosed after the patient expectorated a bronchial cast. Cast analysis showed lymphocytic aggregates with mucin and fibrin. Lymphoscintigraphy revealed abnormal lymphatic collaterals and retrograde trace reflux into the superior mediastinum, a picture consistent with thoracic duct lymph leakage into the tracheobronchial tree. The pathogenesis of PB is not fully understood, especially in patients with CHD. Chyle in bronchial casts suggests abnormal lymphatic flow. Reports of lymph flow abnormalities, especially endobronchial lymph leakage in CHD are limited. Lymphoscintigraphy in our case demonstrated clear evidence of retrograde lymph reflux and leakage into the bronchial tree. The case presented suggests that in some patients following Fontan surgery, high intrathoracic lymphatic pressure and retrograde lymph flow may contribute to recurrent cast formation. Finding the underlying lymphatic abnormality helps in specific case management. Lymphoscintigraphy is a safer and easier method than lymphangiography. Surgical lymphatic-venous shunting may be possible in select cases.

Lymphatic route of transport and pharmacokinetics of Micrurus fulvius (coral snake) venom in sheep

The contribution of the lymphatic system to the absorption and systemic bioavailability of Micrurus fulvius venom after subcutaneous (SC) administration was assessed using a central lymph-cannulated sheep model. Micrurus fulvius venom was administered either by intravenous bolus (IV) or subcutaneous injection (SC) in 12 sheep with and without thoracic duct cannulation and drainage. Venom concentration in serum and lymph was determined by a sandwich enzyme-linked immunosorbent assay (ELISA) in samples collected over a 6-hour period and in tissues harvested at the end of the experiment. Pharmacokinetic parameters were determined by a non-compartmental analysis. In the lymphatic cannulated group, over the 6 hours after the venom was administered, 69% of administered dose was accounted for in blood (45%) and lymph (25%). Negligible levels of venom were detected in organs and urine implying that the steady state observed after SC administration is maintained by a slow absorption process. Comparison of kinetics of the thoracic duct cannulated and non-cannulated groups showed that lymphatic absorption contributed in an important way to maintenance of this steady state. These results show that the limiting process in the pharmacokinetics of Micrurus fulvius venom following SC administration is absorption, and that the lymphatic system plays a key role in this process.

Overlapping biomarkers, pathways, processes and syndromes in lymphatic development, growth and neoplasia

Recent discoveries in molecular lymphology, developmental biology, and tumor biology in the context of long-standing concepts and observations on development, growth, and neoplasia implicate overlapping pathways, processes, and clinical manifestations in developmental disorders and cancer metastasis. Highlighted in this review are some of what is known (and speculated) about the genes, proteins, and signaling pathways and processes involved in lymphatic/blood vascular development in comparison to those involved in cancer progression and spread. Clues and conundra from clinical disorders that mix these processes and mute them, including embryonic rests, multicentric nests of displaced cells, uncontrolled/invasive "benign" proliferation and lymphogenous/hematogenous "spread", represent a fine line between normal development and growth, dysplasia, benign and malignant neoplasia, and "metastasis". Improved understanding of these normal and pathologic processes and their underlying pathomechanisms, e.g., stem cell origin and bidirectional epithelial-mesenchymal transition, could lead to more successful approaches in classification, treatment, and even prevention of cancer and a whole host of other diseases.

Successful treatment of plastic bronchitis with low fat diet and subsequent thoracic duct ligation in child with fontan physiology

Plastic bronchitis is a rare condition characterized by the formation and expectoration of long, branching bronchial casts that develop in the tracheobronchial tree and cause airway obstruction. Plastic bronchitis has become increasingly recognized as a feared complication of the Fontan operation with a mortality of up to 50%. We report an 11 year old boy who developed severe plastic bronchitis following Fontan repair and the successful long-term control of cast formation utilizing a low-fat diet and subsequent thoracic duct ligation.

General surgery, translational lymphology and lymphatic surgery

A wide clinical experience in General Surgery has brought about a remarkable knowledge about lymphatic disorders both primary and secondary ones. Diagnostic and histopathological studies of lymphatic diseases allowed to better understand etiological aspects and pathophysiological mechanisms responsible of complex clinical features correlated to lymphatic dysfunctions. Translational lymphologic basic and clinical researches permitted to improve therapeutical approaches both from the medical and surgical point of view. Thus, strategies of treatment were proposed to prevent lymphatic injuries, to avoid lymphatic complications and to treat lymphatic diseases early in order to be able even to cure these pathologies.

Gastrointestinal lymphatics in health and disease

Lymphatics perform essential transport and immune regulatory functions to maintain homeostasis in the gastrointestinal (GI) system. Although blood and lymphatic vessels function as parallel and integrated systems, our understanding of lymphatic structure, regulation and functioning lags far behind that of the blood vascular system. This chapter reviews lymphatic flow, differences in lymphangiogenic and hemangiogenic factors, lymphatic fate determinants and structural features, and examines how altered molecular signaling influences lymphatic function in organs of the GI system. Innate errors in lymphatic development frequently disturb GI functioning and physiology. Expansion of lymphatics, a prominent feature of GI inflammation, may also play an important role in tissue restitution following injury. Destruction or dysregulation of lymphatics, following injury, surgery or chronic inflammation also exacerbates GI disease activity. Understanding the physiological roles played by GI lymphatics is essential to elucidating their underlying contributions to forms of congenital and acquired forms of GI pathology, and will provide novel approaches for therapy.

Connexin37 and Connexin43 deficiencies in mice disrupt lymphatic valve development and result in lymphatic disorders including lymphedema and chylothorax

Intraluminal valves are required for the proper function of lymphatic collecting vessels and large lymphatic trunks like the thoracic duct. Despite recent progress in the study of lymphvasculogenesis and lymphangiogenesis, the molecular mechanisms controlling the morphogenesis of lymphatic valves remain poorly understood. Here, we report that gap junction proteins, or connexins (Cxs), are required for lymphatic valvulogenesis. Cx37 and Cx43 are expressed early in mouse lymphatic development in the jugular lymph sacs, and later in development these Cxs become enriched and differentially expressed by lymphatic endothelial cells on the upstream and downstream sides of the valves. Specific deficiencies of Cx37 and Cx43 alone or in combination result in defective valve formation in lymphatic collecting vessels, lymphedema, and chylothorax. We also show that Cx37 regulates jugular lymph sac size and that both Cx37 and Cx43 are required for normal thoracic duct development, including valve formation. Another Cx family member, Cx47, whose human analog is mutated in some families with lymphedema, is also highly enriched in a subset of endothelial cells in lymphatic valves. Mechanistically, we present data from Foxc2-/- embryos suggesting that Cx37 may be a target of regulation by Foxc2, a transcription factor that is mutated in human lymphedema-distichiasis syndrome. These results show that at least three Cxs are expressed in the developing lymphatic vasculature and, when defective, are associated with clinically manifest lymphatic disorders in mice and man.