Nonmalignant Adult Thoracic Lymphatic Disorders

Clinical approach for pulmonary lymphatic disorders

In this editorial, we discuss the clinical implications of the article “Lymphatic plastic bronchitis and primary chylothorax: A study based on computed tomography lymphangiography” published by Li et al. Pulmonary lymphatic disorders involve abnormalities in the lymphatic tissues within the thoracic cavity. Specifically, pulmonary lymphatic perfusion syndrome describes a condition where the flow of lymphatic fluid in the lungs is redirected towards abnormally widened lymphatic vessels. Clinically, individuals with this syndrome may experience symptoms such as chyloptysis, plastic bronchitis (PB), chylothorax, chylopericardium, and interstitial lung disease. These disorders can be caused by various factors, including PB, chylothorax, and complex lymphatic malformations. Advancements in lymphatic imaging techniques, such as intranodal lymphangiography, computed tomography lymphangiography, and dynamic contrast-enhanced magnetic resonance lymphangiography, have enabled the detection of abnormal lymphatic flow. This has enhanced our understanding of the pathophysiology of these conditions. Additionally, innovative minimally invasive treatments, such as thoracic duct embolization, selective embolization of lymphatic channels, and surgical procedures aim to improve clinical condition of patients and address their dietary needs.

Imaging and Interventions for Lymphatic and Lymphatic-related Disorders

The lymphatic system is critical in fluid balance homeostasis. Yet, until recently, lymphatic imaging has been outside of mainstream medicine due to a lack of robust imaging and interventional options. However, during the last 20 years, both clinical lymphatic imaging and interventions have shown dramatic advancement. The key to imaging advancement has been the interstitial delivery of contrast agents through lymphatic-rich tissues. These techniques include intranodal lymphangiography and dynamic contrast-enhanced MR lymphangiography. These methods provide the ability to image and recognize lymphatic anatomy and pathologic conditions. Percutaneous thoracic duct catheterization and embolization became the first widely accepted interventional technique for the management of chyle leaks. Advances in interstitial lymphatic embolization, as well as liver and mesenteric lymphatic interventions, have broadened the scope of possible lymphatic interventions. Also, recent techniques of lymphatic decompression allow for the treatment of a variety of lymphatic disorders. Finally, immunologic studies of central lymphatic fluid reveal the potential of lymphatic interventions on immunity. These advances herald an exciting new chapter for lymphatic imaging and interventions in the coming years.

Kaposiform lymphangiomatosis: Diagnosis, pathogenesis, and treatment

Kaposiform lymphangiomatosis (KLA) is a life-threatening rare disease that can cause substantial morbidity, mortality, and social burdens for patients and their families. Diagnosis often occurs long after initial symptoms, and there are few centers in the world with the expertise to diagnose and care for patients with the disease. KLA is a lymphatic anomaly and significant advancements have been made in understanding its pathogenesis and etiology since its first description in 2014. This review provides multidisciplinary, comprehensive, and state-of-the-art information on KLA patient presentation, diagnostic imaging, pathology, organ involvement, genetics, and pathogenesis. Finally, we describe current therapeutic approaches, important areas for research, and challenges faced by patients and their families. Further insights into the pathogenesis of KLA may advance our understanding of other vascular anomalies given that similar signaling pathways may be involved.

CT Features of Lymphatic Plastic Bronchitis in Adults: Correlation with Multimodality Lymphatic Imaging

Purpose

To distinguish CT patterns of lymphatic and nonlymphatic causes of plastic bronchitis (PB) through comparison with lymphatic imaging.

Materials and Methods

In this retrospective study, chest CT images acquired prior to lymphatic workup were assessed in 44 patients with PB from January 2014 to August 2020. The location and extent of ground-glass opacity (GGO) was compared with symptoms and lymphatic imaging. Statistical analysis was performed using descriptive statistics, logistic regression, Pearson correlation coefficient, and unweighted κ coefficient for interobserver agreement. Sensitivity and specificity of GGO for lymphatic PB were calculated.

Results

Lymphatic imaging was performed in 44 patients (median age, 52 years ± 21 [IQR]; 23 women): 35 with lymphatic PB and nine with nonlymphatic PB. GGO was more frequently observed in patients with lymphatic PB than in those with nonlymphatic PB (91% [32 of 35] vs 33% [three of nine]; P < .001). Univariate logistic regression confirmed this result by showing that GGO was a significant predictor of lymphatic PB (odds ratio, 21 (95% CI: 3.8, 159.7). The model areas under the receiver operating characteristic curve (AUCs) of GGO unadjusted and adjusted for demographics were 0.79 and 0.86, respectively. The location of GGO correlated with lymphatic imaging and bronchoscopic findings. Overall sensitivity and specificity of GGO for lymphatic PB were 91% (32 of 35; 95% CI: 76, 98) and 67% (six of nine; 95% CI: 30, 93), respectively.

Conclusion

Patients with lymphatic PB predominantly had multifocal GGO with or without a "crazy paving" pattern; identification of GGO should prompt lymphatic workup in this frequently misdiagnosed condition.Keywords: Lymphography, Lymphatic, CT, Tracheobronchial Tree, Thorax© RSNA, 2022See also commentary by Kligerman and White in this issue.

A census of the lung: CellCards from LungMAP

The human lung plays vital roles in respiration, host defense, and basic physiology. Recent technological advancements such as single-cell RNA sequencing and genetic lineage tracing have revealed novel cell types and enriched functional properties of existing cell types in lung. The time has come to take a new census. Initiated by members of the NHLBI-funded LungMAP Consortium and aided by experts in the lung biology community, we synthesized current data into a comprehensive and practical cellular census of the lung. Identities of cell types in the normal lung are captured in individual cell cards with delineation of function, markers, developmental lineages, heterogeneity, regenerative potential, disease links, and key experimental tools. This publication will serve as the starting point of a live, up-to-date guide for lung research at https://www.lungmap.net/cell-cards/. We hope that Lung CellCards will promote the community-wide effort to establish, maintain, and restore respiratory health.

Lymphangioleiomyomatosis: pathogenesis, clinical features, diagnosis, and management

Lymphangioleiomyomatosis (LAM) is a slowly progressive, low-grade, metastasising neoplasm of women, characterised by infiltration of the lung parenchyma with abnormal smooth muscle-like cells, resulting in cystic lung destruction. The invading cell in LAM arises from an unknown source and harbours mutations in tuberous sclerosis complex (TSC) genes that result in constitutive activation of the mechanistic target of rapamycin (mTOR) pathway, dysregulated cellular proliferation, and a programme of frustrated lymphangiogenesis, culminating in disordered lung remodelling and respiratory failure. Over the past two decades, all facets of LAM basic and clinical science have seen important advances, including improved understanding of molecular mechanisms, novel diagnostic and prognostic biomarkers, effective treatment strategies, and comprehensive clinical practice guidelines. Further research is needed to better understand the natural history of LAM; develop more powerful diagnostic, prognostic, and predictive biomarkers; optimise the use of inhibitors of mTOR complex 1 in the treatment of LAM; and explore novel approaches to the development of remission-inducing therapies.

Trans-cervical thoracic duct embolization for post-surgical left Chylothorax in a patient with multifocal lymphatic malformations

Background

Mediastinal and abdominal lymphatic malformations may not be diagnosed until adulthood. Radiologic and pathologic diagnosis is often challenging due to the rarity of the lesion. Surgical excision of these lesions may be curative but lymphatic leak is a known complication. Lymphatic duct embolization may then be required to treat the leak.

Case presentation

We describe a patient with post-surgical chylothorax where thoracic duct lymphangiography and embolization was performed by catheterizing the thoracic duct at the venous angle where it drains into the subclavian vein.

Conclusion

Lymphatic duct embolization can be challenging in patients with lymphatic malformations. In these patients, if there is adequate visualization on ultrasound or fluoroscopy, terminal aspect of the thoracic duct can be accessed through the subclavian vein to perform the procedure.

A breathless teenager

A 14-year-old girl presented to hospital with breathlessness and fatigue. On admission she was hypoxaemic with oxygen saturations of 90%, tachycardic with a heart rate of 120 beats·min⁻¹ and tachypnoeic with a respiratory rate of 40–50 breaths·min⁻¹.

In children with persistent chylothoraces of unknown origin, intranodal lymphangiography can be used to help identify the source of a leak. This may enable embolisation with glue and coils to enable resolution of the chylothoraces.https://bit.ly/3gskhgJ

Lymphatic Malformations: Genetics, Mechanisms and Therapeutic Strategies

Lymphatic vessels maintain tissue fluid homeostasis by returning to blood circulation interstitial fluid that has extravasated from the blood capillaries. They provide a trafficking route for cells of the immune system, thus critically contributing to immune surveillance. Developmental or functional defects in the lymphatic vessels, their obstruction or damage, lead to accumulation of fluid in tissues, resulting in lymphedema. Here we discuss developmental lymphatic anomalies called lymphatic malformations and complex lymphatic anomalies that manifest as localized or multifocal lesions of the lymphatic vasculature, respectively. They are rare diseases that are caused mostly by somatic mutations and can present with variable symptoms based upon the size and location of the lesions composed of fluid-filled cisterns or channels. Substantial progress has been made recently in understanding the molecular basis of their pathogenesis through the identification of their genetic causes, combined with the elucidation of the underlying mechanisms in animal disease models and patient-derived lymphatic endothelial cells. Most of the solitary somatic mutations that cause lymphatic malformations and complex lymphatic anomalies occur in genes that encode components of oncogenic growth factor signal transduction pathways. This has led to successful repurposing of some targeted cancer therapeutics to the treatment of lymphatic malformations and complex lymphatic anomalies. Apart from the mutations that act as lymphatic endothelial cell-autonomous drivers of these anomalies, current evidence points to superimposed paracrine mechanisms that critically contribute to disease pathogenesis and thus provide additional targets for therapeutic intervention. Here, we review these advances and discuss new treatment strategies that are based on the recently identified molecular pathways.

Abnormal Pulmonary Lymphatic Flow on Novel Lymphangiographic Imaging Supports a Common Etiology of Lymphatic Plastic Bronchitis and Nontraumatic Chylothorax

Background: This study evaluates whether dynamic contrast-enhanced magnetic resonance lymphangiography (DCMRL) and thoracic duct lymphangiography (TDL) findings in adults with lymphatic plastic bronchitis (PB) and/or nontraumatic chylothorax (NTC) support a shared pathophysiology. Materials and Results: Retrospective review of clinical and imaging findings in patients who underwent DCMRL and TDL at a single institution from March 2017 to March 2019. Categorical variables were compared with Fisher's exact test. Twenty-eight patients (median age 61 ± 21 years, 15 women) presenting with lymphatic PB (n = 13), NTC (n = 10), or both (n = 5) were included. Lymphatic imaging demonstrated pulmonary lymphatic perfusion (PLP) in all patients. A patent thoracic duct (TD) with retrograde flow was seen in 53.4% (7/13) of patients with PB, 60% (6/10) of patients with NTC, and 20% (1/5) of patients with both (p = 0.69). An occluded TD with retrograde flow was seen in 30.8% (4/13) of patients with PB, 30% (3/10) of patients with NTC, and 80% (4/5) of patients with both (p = 0.12). Similar patterns of PLP between DCMRL and TDL were seen in 96.2% (25/26) of patients. Conclusions: DCMRL and TDL demonstrated similar findings in patients with lymphatic PB and/or NTC, supporting a common etiology. This supports the hypothesis that the clinical presentation depends on the proximity of abnormal lymphatic vessels to the pleural cavity, resulting in chylothorax, or bronchial mucosa, resulting in PB.

Abnormal pulmonary lymphatic flow in patients with paediatric pulmonary lymphatic disorders: Diagnosis and treatment

Pulmonary lymphatic disorders are characterized by the presence of the abnormal lymphatic tissues in the thoracic cavity, presenting clinically as chylothorax, chylopericardium, chyloptysis, interstitial lung disease and plastic bronchitis. These conditions include: neonatal chylothorax, cardiac and non-cardiac plastic bronchitis, non-traumatic chylothorax, post congenital cardiac surgery chylothorax and complex lymphatic malformations. Recently developed lymphatic imaging techniques, such as intranodal lymphangiography and dynamic contrast enhanced magnetic resonance lymphangiography demonstrated abnormal pulmonary lymphatic flow from thoracic duct into pulmonary parenchyma as a pathophysiological mechanism of these diseases. Novel minimally invasive lymphatic interventions, such as thoracic duct embolization, interstitial lymphatic embolization and surgical lympho-venous anastomosis, provide an effective treatment of these conditions.

The emergence of targetable MEKanisms in sporadic lymphatic disorders

Sporadic lymphatic diseases are orphans among orphans in the medical community, a diverse collection of disorders at the intersection of cardiac, gastrointestinal, pulmonary, dermatologic, and oncologic disease that receives only passing attention in medical school and that no subspecialty in medicine fully embraces as its own. They often present in a confusing and illusive manner, with a fractured bone, expectoration of blood or a branching airway cast, a swollen limb or a collection of chylous material; protean manifestations that can challenge even the most expert diagnostician. Yet many of these acquired disorders have been discovered to have a targetable genetic basis, and as the case report of Foster et al (2020) demonstrates, the sedulous clinician–patient dyad can be rewarded with an almost miraculous result when the molecular pathogenesis of the disease is pursued and an exquisitely targeted therapy is administered.

Magnetic Resonance Lymphangiography

Dynamic contrast-enhanced magnetic resonance lymphangiography is a novel technique to image central conducting lymphatics. It is performed by injecting contrast into groin lymph nodes and following passage of contrast through lymphatic system using T1-weighted MR images. Currently, it has been successfully applied to image and plan treatment of thoracic duct pathologies, lymphatic leaks, and other lymphatic abnormalities such as plastic bronchitis. It is useful in the assessment of chylothorax and chyloperitoneum. Its role in other areas such as intestinal lymphangiectasia and a variety of lymphatic anomalies is likely to increase.

Multidisciplinary guidelines for initial evaluation of complicated lymphatic anomalies-expert opinion consensus

OBJECTIVE

Complicated lymphatic anomalies (CLAs) are chronic, progressive, and debilitating conditions that share clinical features, yet key elements for optimal evaluation and management have not been established. We aimed to formulate expert opinion consensus-based guidelines for comprehensive evaluation of CLAs.

STUDY DESIGN

Patient support groups dedicated to CLAs organized an international conference for vascular anomaly experts from 16 specialties to address the objective. Participants received a set of questions before the meeting and reviewed the literature. Data extracted from international lymphatic anomaly registries were presented and the group separated for panel discussions during the conference. The recommendations achieving consensus within the panel were presented to the entire audience. Open debate occurred until majority approval was achieved.

RESULTS

The expert group was composed of 52 physicians who defined the clinical elements required to evaluate and diagnose a CLA. The radiology panel established the preferred anatomical and functional imaging methods for diagnosis and the elements required to be described during interpretation. Two medical panels compiled the metabolic and hematologic tests at diagnosis and also recommended functional studies. The surgical group recommended precautions for biopsy and the pathology panel provided biopsy specimen processing guidelines.

CONCLUSIONS

Patients with CLAs require a comprehensive and targeted diagnostic plan for appropriate management, prevention of complications, and conservation of resources. As this population is managed by diverse medical and surgical specialties, we offer an expert multidisciplinary consensus-based opinion on the current literature and on data extracted from international lymphatic anomaly registries.

Diffuse pulmonary lymphangiomatosis: A rare case report in an adult

RATIONALE

Diffuse pulmonary lymphangiomatos (DPL) is a rare aggressive lymphatic disorder characterized by proliferation of anastomozing lymphatic vessels and extremely rare in adult patients.

PATIENT CONCERNS

We report a case of diffuse pulmonary lymphangiomatosis in 59-year-old man presented with cough and sputum for 2 months.

DIAGNOSES

Combining clinical manifestations with results of radiological, bronchoscopy, and surgical lung biopsy, it was consistent with the diagnosis of DPL.

INTERVENTIONS

After bronchoalveolar lavage and biopsy, symptom of cough got worse suddenly accompanied by excessive chyloptysis. The patient received an emergency surgical intervention and low fat medium chain fat treatment.

OUTCOMES

The patient was discharged with a much better health condition.

LESSONS

This case report is the oldest patient reported in the English literature, to the best of our knowledge. Serious complications of bronchoscopy should be considered, especially in DPL patients with severely enlarged mediastinum or with thin-walled translucent vesicles under endoscopy.

Immune Checkpoint Ligand PD-L1 Is Upregulated in Pulmonary Lymphangioleiomyomatosis

Pulmonary lymphangioleiomyomatosis (LAM) is a slow-progressing metastatic disease that is driven by mutations in the tumor suppressor tuberous sclerosis complex 1/2 (TSC1/2). Rapamycin inhibits LAM cell proliferation and is the only approved treatment, but it cannot cause the regression of existing lesions and can only stabilize the disease. However, in other cancers, immunotherapies such as checkpoint blockade against PD-1 and its ligand PD-L1 have shown promise in causing tumor regression and even curing some patients. Thus, we asked whether PD-L1 has a role in LAM progression. In vitro, PD-L1 expression in murine Tsc2-null cells is unaffected by mTOR inhibition with torin but can be upregulated by IFN-γ. Using immunohistochemistry and single-cell flow cytometry, we found increased PD-L1 expression both in human lung tissue from patients with LAM and in Tsc2-null lesions in a murine model of LAM. In this model, PD-L1 is highly expressed in the lung by antigen-presenting and stromal cells, and activated T cells expressing PD-1 infiltrate the affected lung. In vivo treatment with anti-PD-1 antibody significantly prolongs mouse survival in the model of LAM. Together, these data demonstrate that PD-1/PD-L1-mediated immunosuppression may occur in LAM, and suggest new opportunities for therapeutic targeting that may provide benefits beyond those of rapamycin.

Pulmonary manifestations in tuberous sclerosis complex

Tuberous sclerosis complex has manifestations in many organ systems, including brain, heart, kidney, skin, and lung. The primary manifestations in the lung are lymphangioleiomyomatosis (LAM) and multifocal micronodular pneumocyte hyperplasia (MMPH). LAM affects almost exclusively women, and causes cystic lung destruction, pneumothorax, and chylous pleural effusions. LAM can lead to dyspnea, oxygen dependence, and respiratory failure, with more rapid disease progression during the premenopausal years. In contrast, MMPH affects men and women equally, causing small nodular pulmonary deposits of type II pneumocytes that rarely progress to symptomatic disease. Here, we review the clinical features and pathogenesis of LAM and MMPH.

Chylothorax and constrictive pericarditis in a woman due to generalized lymphatic anomaly: a case report

Background

Generalized lymphatic anomaly (GLA) is characterized by diffuse or multicentric proliferation of dilated lymphatic vessels resembling common lymphatic malformations. Compared with soft tissue or bone involvement, thoracic involvement may be associated with a worse prognosis.

Case presentation

We reported a case of GLA with chylothorax and constrictive pericarditis in a 29-year-old woman. This patient exhibited remarkable features, including a continuously hemorrhagic chylothorax, constrictive pericarditis, and involvement of bone and neck lymph nodes. After attempting to manage her condition with conservative treatment, the patient underwent pericardial stripping surgery. Exploration revealed abundant hyperplasia of tubular tissue in the aortopulmonary window in both pleural cavities.

Conclusions

This case highlights the importance of maintaining the clinical suspicion of GLA during the follow-up of chylothorax patients. Aggressive pericardial surgery, which is important for both diagnosis and treatment, should be performed in patients with GLA with constrictive pericarditis.

Pulmonary lymphatic vessel morphology: a review

Our understanding of lymphatic vessels has been advanced by the recent identification of relatively specific lymphatic endothelium markers, including Prox-1, VEGFR3, podoplanin and LYVE-1. The use of lymphatic markers has led to the observation that, contrary to previous assumptions, human lymphatic vessels extend deep inside the pulmonary lobule, either in association with bronchioles, intralobular arterioles or small pulmonary veins. Pulmonary lymphatic vessels may thus be classified into pleural, interlobular (in interlobular septa) and intralobular. Intralobular lymphatic vessels may be further subdivided in: bronchovascular (associated with a bronchovascular bundle), perivascular (associated with a blood vessel), peribronchiolar (associated with a bronchiole), and interalveolar (in interalveolar septa). Most of the intralobular lymphatic vessels are in close contact with a blood vessel, either alone or within a bronchovascular bundle. A minority is associated with a bronchiole, and small lymphatics are occasionally present even in interalveolar septa, seemingly independent of blood vessels or bronchioles. The lymphatics of the interlobular septa often contain valves, are usually associated with the pulmonary veins, and connect with the pleural lymphatics. The large lymphatics associated with bronchovascular bundles have similar characteristics to pleural and interlobular lymphatics and may be considered conducting vessels. The numerous small perivascular lymphatics and the few peribronchiolar ones that are found inside the lobule are probably the absorbing compartment of the lung responsible for maintaining the alveolar interstitium relatively dry in order to provide a minimal thickness of the air-blood barrier and thus optimize gas diffusion. These lymphatic populations could be differentially involved in the pathogenesis of diseases preferentially involving distinct lung compartments.

Causes and manifestations of chylothorax in children in China: Experience from a children's medical center, 2007-2017

IMPORTANCE

Chylothorax is the most common cause of pleural effusion in neonates and relatively rare in children. It can cause significant respiratory morbidity. Many clinical entities may contribute to chylothorax.

OBJECTIVE

To investigate the causes and manifestations of chylothorax in infants and children in China.

METHODS

Case records of 107 cases with chylothorax seen in Beijing Children's Hospital from 2007 to 2017 were retrieved and analyzed; follow-up was carried out by telephone.

RESULTS

Of 107 cases, 58.9% (63/107) were primary chylothorax (PC) and 41.1% (44/107) were secondary chylothorax (SC). Also, 36.4% (39/107) were neonatal chylothorax (NC) and 35.5% (38/107) were postoperative chylothorax. In PC with a verified lymphatic anomaly, there was one case of diffuse pulmonary lymphangiomatosis (DPL) and six cases of generalized lymphatic anomaly (GLA), which accounted for 6.5% (7/107) of cases. In most patients, chylothorax was alleviated by conservative treatment based on total parenteral nutrition (TPN); 13.1% (14/107) of cases needed further surgery. In NC, the median duration of TPN was 9 days, but 10 of 20 cases who improved had recurrence upon re-introduction of a fat-free diet, which was alleviated by further TPN. The duration of hospitalization was (23 ± 14) days for congenital chylothorax. Upon long- term follow-up, except for GLA and DPL, most patients were doing well without recurrence.

INTERPRETATION

NC and postoperative chylothorax are the common subtypes. TPN is effective for most patients. Despite a prolonged and fluctuating clinical course, most patients had a good long-term prognosis.

Gorham-Stout Disease Management during Pregnancy

Gorham-Stout Disease (GSD) is a rare lymphatic disorder affecting children or young adults with no predilection of sex. It is generally associated with vanishing bone osteolytic lesions, thoracic and abdominal involvement, and diffuse pulmonary lymphangiomatosis. Chylous effusions and chylothorax, consequent to the abnormal proliferation of lymphatic vessels, may induce respiratory failure with a high mortality risk. Extrapulmonary alterations may include chylous ascites, lymphopenia, and destructing bone disease for overgrowth of lymphatic vessels. Here, we report the case of a young woman who developed a severe and recalcitrant GSD with persistent unilateral chylothorax during pregnancy. The complex management of this patient during and after pregnancy was discussed and compared with literature data to contribute to the definition of a correct diagnostic and therapeutic approach to this rare lymphatic disease.