[Lesions of the visceral mediastinum]. / Läsionen des viszeralen Mediastinums.

BACKGROUND: The visceral or middle mediastinum contains nonvascular (trachea, carina, esophagus, and lymph nodes) and vascular structures (heart, ascending aorta, aortic arch, descending aorta, superior vena cava, intrapericardial pulmonary arteries, thoracic duct). OBJECTIVES: The various pathologies of the visceral mediastinum and imaging features are presented. MATERIALS AND METHODS: Plain film radiography shows the gross anatomy and allows visualization of larger pathologies. However, for detailed anatomic and structural classification more sophisticated imaging techniques are required. Especially computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) are well suited for structural and functional assessment of mediastinal lesions. CONCLUSION: This article summarizes the major pathologies of the visceral mediastinum.

Sonography for assessment of thoracic duct anatomy and physiology before and after meals.

The interest in clinical anatomy of the thoracic duct (TD) has recently grown, owing to discoveries linking its morphology to pathologies such as heart failure or liver cirrhosis. In the light of this knowledge, a cost-efficient and reliable in-vivo imaging method of TD should be devised. Ultrasonography satisfies these criteria and hence is a promising tool for assessment of TD's anatomy and function. Thirty-one healthy volunteers attended the examination after 6 h of fasting and 2 h without drink. Ultrasound of the left supraclavicular fossa was performed in search of TD's orifice into the venous angle. In each case, the largest diameter, number of orifices, presence of valves, tributaries, and motility of the TD were examined. We performed examinations in three sessions: after fasting, after standardized meal and 1 h after the meal. The statistical significance has varied among the three sessions. The strongest connection was shown in the third examination. The TD was visualized in 31 cases, 35 orifices were found, most of which drained into the venous angle. Multiple orifices were seen in four cases and valves in 15 cases. Tributaries were present in 17 cases. Mean widest and orifice diameter measured 3.23 and 2.0 mm, respectively. Spontaneous peristaltic-like movements of the TD were observed in 25 cases. We demonstrated that ultrasound is useful for assessment of TD's anatomy, allowing to visualize and quantify its key features. Moreover, our study is presumably the first to capture and describe TD's motility in vivo.

The cisterna chyli: a systematic review of definition, prevalence, and anatomy.

The cisterna chyli is a lymphatic structure found at the caudal end of the thoracic duct that receives lymph draining from the abdominal and pelvic viscera and lower limbs. In addition to being an important landmark in retroperitoneal surgery, it is the key gateway for interventional radiology procedures targeting the thoracic duct. A detailed understanding of its anatomy is required to facilitate more accurate intervention, but an exhaustive summary is lacking. A systematic review was conducted, and 49 published human studies met the inclusion criteria. Studies included both healthy volunteers and patients and were not restricted by language or date. The detectability of the cisterna chyli is highly variable, ranging from 1.7 to 98%, depending on the study method and criteria used. Its anatomy is variable in terms of location (vertebral level of T10 to L3), size (ranging 2-32 mm in maximum diameter and 13-80 mm in maximum length), morphology, and tributaries. The size of the cisterna chyli increases in some disease states, though its utility as a marker of disease is uncertain. The anatomy of the cisterna chyli is highly variable, and it appears to increase in size in some disease states. The lack of well-defined criteria for the structure and the wide variation in reported detection rates prevent accurate estimation of its natural prevalence in humans.

Anatomical study of the thoracic duct and its clinical implications in thoracic and pediatric surgery, a 70 cases cadaveric study.

INTRODUCTION: Given the high variability and fragility of the thoracic duct, good knowledge of its anatomy is essential for its repair or to prevent iatrogenic postoperative chylothorax. The objective of this study was to define a site where the thoracic duct is consistently found for its ligation. The second objective was to define an anatomically safe surgical pathway to prevent iatrogenic chylothorax in surgery for aortic arch anomalies with vascular ring, through better knowledge of the anatomical relationships of the thoracic duct. METHODS: Seventy adult formalin-fixed cadavers were dissected. The anatomical relationships of the thoracic duct were reported at the postero-inferior mediastinum, at levels T3 and T4. RESULTS: The thoracic duct was consistently situated between the left anterolateral border of the azygos vein and the right border of the aorta between levels T9 and T10, whether it was simple, double, or plexiform. It was located medially, anteromedially, or posteriorly to the left subclavian artery in 51%, 21%, and 28% of the cases, respectively, at the level of T3. At T4, it was posteromedial in 27% of the cases or had no direct relationship with the aortic arch. CONCLUSION: These results favor mass ligation of the thoracic duct at levels T9-T10 between the right border of the aorta and the azygos vein, eventually including the latter. To prevent iatrogenic postoperative chylothorax in aortic arch anomalies with vascular ring surgery, we recommend remaining strictly lateral to the left subclavian artery at the level of T3 to reach the aortic arch anomalies with vascular ring at T4.

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 Pathways of the Thorax: Predictable Patterns of Spread.

OBJECTIVE. This article reviews thoracic lymphatic pathways and tributaries, discusses lymphatic anatomic variants and their clinical implications, and emphasizes common patterns of thoracic lymphadenopathy from extrapulmonary malignancies. CONCLUSION. Recognition of common patterns and pathways of thoracic lymphatic drainage can help identify the site of tumor origin and allow a more focused examination of disease extent, both of which are important for disease prognosis and management.

Anatomic variations of cervical part of thoracic duct: a systematic review

The thoracic duct is the largest lymphatic channel of the human body, and presents with great anatomical variation at its cervical segment. Injury of the thoracic duct can result in local or systemic severe complications. In order to identify the prevalence of the anatomical variations of the terminal portion of the thoracic duct, this study was per-formed according to PRISMA guidelines. Τhe I-square was used to assess heterogeneity. Α wide search was conducted in PubMed/ Embase/ Medline until September 2019.Out of 28 potentially relevant studies identified by literature search, 14 studies comprising 751 patients were included in the final analysis. The pre-valence of thoracic duct ending with a single terminal duct was found at 63% (37%-85%) of the patients. Left internal jugular vein, left subclavian vein, left jugulosubclavian angle, or another vein, was found to receive at least one terminal branch of the thoracic duct in 32% (18%-47%), 27% (13%-43%), 32% (16%-51%) and 7% (0%-19%) of the cases, respectively. Each time the thoracic duct drained into the left internal jugular vein, the left subclavian vein and the left jugulosubclavian angle, a single terminal branch pattern was observedin 58% (21%-92%), 49% (6%- 93%) and 76% (49-96%) of the cases respectively

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Combining non-contrast enhanced magnetic resonance thoracic ductography with vascular contrast-enhanced computed tomography to identify the canine thoracic duct.

Background: In humans, visualization of the thoracic duct by magnetic resonance imaging (MRI) has been attempted, and recent advances have enabled clinicians to visualize the thoracic duct configuration in a less invasive manner. Moreover, MRI does not require contrast media, and it enables visualization of morphological details of the thoracic structures. In veterinary practice, the thoracic duct has not been visualized three dimensionally in MRI. Aim: This study aimed to assess the performance of our magnetic resonance thoracic ductography (MRTD) technique to visualize the thoracic duct and the surrounding 3D anatomical structures by combining MRTD and vascular contrast-enhanced thoracic computed tomography (CT) images in dogs. Methods: Five adult male beagle dogs (11.4-12.8 kg) were included in this study. Sagittal and transverse T2-weighted images were scanned in MRI. Scanning in MRTD used a single-shot fast spin echo sequence with a respiratory gate. CT was performed after the intravenous injection of contrast medium. All MRTD and CT images were merged using a workstation. Results: The thoracic ducts were identified in MRTD images of all dogs, and the surrounding anatomical structures were located with the aid of contrast-enhanced thoracic CT. In all dogs, the thoracic ducts coursed along the right-dorsal side of the aorta, cranially from the L2 level. Thereafter, these bent to the left side at the aortic arch and curved at the left external jugular vein angle. A comparison of the number of thoracic ducts at each vertebra between transverse T2WI and MRTD did not reveal any significant differences for all vertebrae. Conclusion: The results from our study suggest that MRTD using the single-shot fast spin echo sequence could be a useful tool for visualization of the thoracic duct. Furthermore, the image merged from MRTD and vascular-enhanced images provided detailed anatomical annotation of the thorax. The MRTD protocol described in this study is safe and easily adaptable, without the need for contrast medium injection into the lymph system. In addition, the images fused from MRTD and vascular contrast-enhanced CT image of the thorax could provide detailed anatomical annotations for preoperative planning.

Anatomy of the lymphovenous valve of the thoracic duct in humans.

The majority of lymph generated in the body is returned to the blood circulation via the lymphovenous junction (LVJ) of the thoracic duct (TD). A lymphovenous valve (LVV) is thought to guard this junction by regulating the flow of lymph to the veins and preventing blood from entering the lymphatic system. Despite these important functions, the morphology and mechanism of this valve remains unclear. The aim of this study was to investigate the anatomy of the LVV of the TD. To do this, the TD and the great veins of the left side of the neck were harvested from 16 human cadavers. The LVJs from 12 cadavers were successfully identified and examined macroscopically, microscopically, and using microcomputed tomography. In many specimens, the TD branched before entering the veins. Thus, from 12 cadavers, 21 LVJs were examined. Valves were present at 71% of LVJs (15/21) and were absent in the remainder. The LVV, when present, was typically a bicuspid semilunar valve, although the relative size and position of its cusps were variable. Microscopically, the valve cusps comprised luminal extensions of endothelium with a thin core of collagenous extracellular matrix. This study clearly demonstrated the morphology of the human LVV. This valve may prevent blood from entering the lymphatic system, but its variability and frequent absence calls into question its utility. Further structural and functional studies are required to better define the role of the LVV in health and disease.

Anatomical variations in distal portion of the thoracic duct-A systematic review.

The objective of this study was to identify and analyze the anatomical variations in the termination of the thoracic duct (TD) in cadavers or patients by anatomical dissections and surgical or radiological procedures for better knowledge of the interindividual variations through a systematic review. The search strategy included PubMed and reference tracking. Studies were identified by searching the electronic Medline databases. The search terms included "TD," "Jugular Vein," "Subclavian Vein," or "Cervical," and the protocol used is reported herein. These search results yielded 20 qualitative review articles out of the 275 articles consulted. We collected all the important data from these 20 articles with 1,352 TD analyzed by varying sources in our search. Regarding the characteristics of the studies and the anatomy of the TD, the results were heterogeneous. The TD most commonly terminates in the internal jugular vein in 54.05% of cases (95% confidence interval [CI]: 54.03; 54.07), in the jugular-venous angle in 25.79% (95% CI: 25.77; 25.81), and in the subclavian vein in 8.16% of cases (95% CI: 8.14;8.18). Other terminations were found in 12% of cases. This systematic review provided an overview of the variations in the distal portion of the TD. This study can be helpful for surgeons in selecting the most appropriate methods to achieve successful surgical results and avoid complications, such as chylothorax; it also offers detailed information on the cervical termination of the TD in new diagnostic and therapeutic methods involving the TD. Clin. Anat. 32:99-107, 2019. © 2019 Wiley Periodicals, Inc.

Anatomy and function of the vertebral column lymphatic network in mice.

Cranial lymphatic vessels (LVs) are involved in the transport of fluids, macromolecules and central nervous system (CNS) immune responses. Little information about spinal LVs is available, because these delicate structures are embedded within vertebral tissues and difficult to visualize using traditional histology. Here we show an extended vertebral column LV network using three-dimensional imaging of decalcified iDISCO+-clarified spine segments. Vertebral LVs connect to peripheral sensory and sympathetic ganglia and form metameric vertebral circuits connecting to lymph nodes and the thoracic duct. They drain the epidural space and the dura mater around the spinal cord and associate with leukocytes. Vertebral LVs remodel extensively after spinal cord injury and VEGF-C-induced vertebral lymphangiogenesis exacerbates the inflammatory responses, T cell infiltration and demyelination following focal spinal cord lesion. Therefore, vertebral LVs add to skull meningeal LVs as gatekeepers of CNS immunity and may be potential targets to improve the maintenance and repair of spinal tissues.

A radio-anatomical correlation study of the cisterna chyli.

Surgical laparoscopic procedures in the retroperitoneal and supramesocolic spaces are increasingly frequent. There is a high risk of iatrogenic intraoperative injury of the retroperitoneal lymphatic structures during these procedures. A precise understanding of the anatomy of the thoracic duct (TD) and the cisterna chyli (CC) is essential for safe surgical procedures in this area. However, routine imaging procedures rarely and often incorrectly visualize the CC. The objective of this study was to evaluate the feasibility of a retrograde injection of the TD to fill the CC with a contrast agent in 16 human cadavers. Both magnetic resonance lymphography (MRI) and computed tomography (CT) studies could be performed on the same anatomical specimen, using a contrast medium which hardened, allowing gross dissection. MRI and CT detectability were evaluated, and imaging results were compared with the anatomical dissection. The CC of 12/16 cadavers were successfully injected, and four were unsuccessful due to technical difficulties, showing the effectiveness of the method. This technique can improve understanding of the anatomy of the TD and CC and provides an original option to study the complex anatomy of these structures by correlating precise cadaveric dissections with cross-sectional imaging.

Histological study of the thin membranous structure made of dense connective tissue around the esophagus in the upper mediastinum.

BACKGROUND: The structure of the fascia in upper mediastinum has already been reported from gross anatomical viewpoints by Sarrazin. But it is necessary to understand meticulous anatomy for thoracoscopic or mediastinoscopic surgery. So herein, we investigate histologically the thin membranous structure made of dense connective tissues. METHODS: Semi-sequential transverse sections of the mediastinum were obtained from three cadavers. Hematoxylin and eosin staining, Elastica van Gieson staining, and Masson trichrome staining were performed to identify the presence and location of the thin membranous structure made of dense connective tissues. RESULTS: The "visceral sheath" and "vascular sheath," as previously described by Sarrazin, were observed histologically. These two thin membranous structures do not surround the esophagus and trachea cylindrically. In addition, the "visceral sheath" on the right side of the upper mediastinum was unclear in comparison to the left side. The "visceral sheath" (on the left side) gradually became unclear, and seemed to almost disappear; the esophagus was found to be very close to the thoracic duct on the caudal side of the bifurcation of the trachea. Although the left recurrent nerve was located inside the "visceral sheath" in all cadavers, the left recurrent nerve lymph nodes were located inside the "visceral sheath" in cadaver 1 and between the "visceral sheath" and "vascular sheath" in cadaver 3. CONCLUSION: The "visceral sheath" around the esophagus in the upper mediastinum was histologically demonstrated; however, the findings were not constant.

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.

The anatomy of the thoracic duct at the level of the diaphragm: A cadaver study.

BACKGROUND: Injury and subsequent leakage of unrecognized thoracic duct tributaries during transthoracic esophagectomy may lead to chylothorax. Therefore, we hypothesized that thoracic duct anatomy at the diaphragm is more complex than currently recognized and aimed to provide a detailed description of the anatomy of the thoracic duct at the diaphragm. BASIC PROCEDURES: The thoracic duct and its tributaries were dissected in 7 (2 male and 5 female) embalmed human cadavers. The level of origin of the thoracic duct and the points where tributaries entered the thoracic duct were measured using landmarks easily identified during surgery: the aortic and esophageal hiatus and the arch of the azygos vein. MAIN FINDINGS: The thoracic duct was formed in the thoracic cavity by the union of multiple abdominal tributaries in 6 cadavers. In 3 cadavers partially duplicated systems were present that communicated with interductal branches. The thoracic duct was formed by a median of 3 (IQR: 3-5) abdominal tributaries merging 8.3cm (IQR: 7.3-9.3cm) above the aortic hiatus, 1.8cm (IQR: -0.4 to 2.4cm) above the esophageal hiatus, and 12.3cm (IQR: 14.0 to -11.0cm) below the arch of the azygos vein. CONCLUSION: This study challenges the paradigm that abdominal lymphatics join in the abdomen to pass the diaphragm as a single thoracic duct. In this study, this occurred in 1/7 cadavers. Although small, the results of this series suggest that the formation of the thoracic duct above the diaphragm is more common than previously thought. This knowledge may be vital to prevent and treat post-operative chyle leakage.

Magnetic resonance thoracic ductography assessment of serial changes in the thoracic duct after the intake of a fatty meal.

The thoracic duct, a terminal lymph vessel, is thought to dilate after the intake of a fatty meal. However, this physiological change has not been well explored in vivo. Therefore, the present study aimed to assess serial changes in the thoracic duct after the intake of a fatty meal using magnetic resonance thoracic ductography (MRTD). Eight healthy volunteers were subjected to one MRTD scan before a fatty meal and eight serial MRTD scans every hour thereafter. The cross-sectional areas of the thoracic duct were estimated using MRTD measurements of the diameters of the thoracic duct at the upper edge of the aortic arch, the tracheal bifurcation, the mid-point between the tracheal bifurcation and the left part of the diaphragm and the left part of the diaphragm. The change-rates in these areas were calculated before and after the fatty meal intake, and the maximal change-rate and timing of its achievement were determined for each subject. The summed change-rates in the four portions of the thoracic duct ranged from -40.1 to 81.3%, with maximal change-rates for each subject ranging from 22.8 to 81.3% (mean, 50.4%). Although individual variations were observed, most subjects (88.9%) exhibited a maximal change-rate at 4-6 h after meal intake, with subsequent decreases at 7-8 h. In conclusion, MRTD revealed a tendency toward thoracic duct enlargement at 4-6 h after the intake of a fatty meal, followed by contraction.

Chest X-ray of a patient with history of pleural effusion.

The presented chest X-ray depicts the thoracic duct anatomy of a 50-year-old man who underwent heart transplantation. His postoperative course was complicated by Candida mediastinitis, treated with débridements and closure of the anterior chest wound with myocutaneous flaps. Postoperatively, he had persistent output from a right-sided chest tube. The fluid appeared milky and its triglycerides level was elevated at 254 mg/dL. The drainage persisted despite a low fat diet. The interventional radiologist identified a leak in the upper thoracic duct. It was embolised with coil and onyx. After the procedure, the chylous pleural effusions resolved. The thoracic duct has been visualised on subsequent chest X-rays (figures 1 and 2).

A review of traumatic chylothorax.

BACKGROUND: Traumatic chylothorax is an extremely rare complication following thoracic trauma or surgery. The aetiology of traumatic chylothorax is dominated by iatrogenic causes, with a reported incidence of 0.5% to 3% following oesophageal surgery. The mortality from a chylothorax post oesophagectomy can be as high as 50%. Iatrogenic causes in total account for approximately 80% of traumatic causes. Non-iatrogenic traumatic chylothoraces are exceedingly uncommon. The complication rate in blunt thoracic trauma is said to be 0.2% to 3%, whilst in penetrating trauma, the incidence is 0.9% to 1.3%. If recognised late or managed poorly, this condition has devastating complications, including nutritional depletion, physiological derangements and immunological depression. This review revisits the anatomy of the thoracic duct, the physiology of chyle production and associated dynamics as well as the current management strategies available for traumatic chylothorax. METHODS: A review of selected English literature from 1980 to 2015 was undertaken. Databases used included Pubmed, Cochrane and Science Direct. Publications of both traumatic and postoperative chylothorax were reviewed. The appropriate literature was analysed by comparing and contrasting content with particular emphasis on management issues. Keywords and phrases were used to achieve a streamlined and focused review of the topic. CONCLUSION: Chylothorax remains a rare complication of thoracic surgery and thoracic trauma. The potential complications can result in serious morbidity and can even be fatal. Understanding the pathophysiology of a chyle leak underpins the principles of management. The overall success of conservative management ranges from 20% to 80%. The timing of surgical intervention remains debatable. Benefits of early surgical intervention are clearly documented, resulting in a gradual shift toward early operative treatment with reports suggesting thoracic duct ligation yielding a 90% success rate. Technological advances such as thoracic duct embolisation, with a potential success rate of 90%, and thoracoscopic interventions are attractive alternatives to orthodox open surgery.

The thoracic duct: clinical importance, anatomic variation, imaging, and embolization.

UNLABELLED: The thoracic duct is the body's largest lymphatic conduit, draining upwards of 75 % of lymphatic fluid and extending from the cisterna chyli to the left jugulovenous angle. While a typical course has been described, it is estimated that it is present in only 40-60% of patients, often complicating already challenging interventional procedures. The lengthy course predisposes the thoracic duct to injury from a variety of iatrogenic disruptions, as well as spontaneous benign and malignant lymphatic obstructions and idiopathic causes. Disruption of the thoracic duct frequently results in chylothoraces, which subsequently cause an immunocompromised state, contribute to nutritional depletion, and impair respiratory function. Although conservative dietary treatments exist, the majority of thoracic duct disruptions require embolization in the interventional suite. This article provides a comprehensive review of the clinical importance of the thoracic duct, relevant anatomic variants, imaging, and embolization techniques for both diagnostic and interventional radiologists as well as for the general medical practitioner. KEY POINTS: • Describe clinical importance, embryologic origin, and typical course of the thoracic duct. • Depict common/lesser-known thoracic duct anatomic variants and discuss their clinical significance. • Outline the common causes of thoracic duct injury and indications for embolization. • Review the thoracic duct embolization procedure including both pedal and intranodal approaches. • Present and illustrate the success rates and complications associated with the procedure.

Anatomical Variations of the Thoracic Duct: A Preliminary Report in Adult and Fetal Specimens.

The study aim is to evaluate anatomical variations of the thoracic duct using a specialized sequential injection procedure. The different types, frequencies, and anatomical topography were recorded and evaluated using 12 adult and 16 fetus specimens. By employing a perfusion pump device, cadavers were sequentially perfused with acrylic colored latex first through the internal marginal vein, then the thoracic duct at the interazygous-aortic recess, and finally through the posterior tibial artery. After perfusion, thoracic ducts were identified, partially dissected, and cadavers fixed by soaking in an aqueous solution of 5% formalin (v/v). Finally, further dissection and detailed photography were performed. Plexus shapes at different levels were clearly evident in 80% of the adult specimens. Whereas the presence of the cisterna chyli was detected in 100% of fetuses as an ampule dilatation at the beginning of the thoracic duct, in only one adult specimen was a dilatation found at the lumbar lymphatic trunk level. Functionally it is not known whether these modified anatomical features (plexus shapes) have served to compensate (as a derivative pathway) for lymphatic hypertension in life as a reflection of lymphatic system challenges and subsequent growth in the adult specimens.