Lymphoscintigraphic Abnormalities Associated with Milroy Disease and Lymphedema-Distichiasis Syndrome

LYMPHOSCORE (Lymphoscintigraphy Scoring Reliability) Reliability of a New Qualitative and Semiquantitative Lymphoscintigraphy Scoring System for Primary Lymphedema

PURPOSE OF THE REPORT

Primary lymphedema (PLE) is a rare chronic disorder. Extremity lymphoscintigraphy offers access for dynamic and functional information on peripheral lymphatics and lymph nodes. We aimed to assess intraobserver and interobserver reliability of a new lymphoscintigraphy quantitative and qualitative scoring system in a homogeneous population of adult patients followed for PLE of the lower limb(s).

PATIENTS AND METHODS

This is a monocentric retrospective study. Clinical files of patients who underwent a lymphoscintigraphy were reviewed for inclusion. Lymphoscintigraphies were interpreted twice by 2 observers with a washout period. To assess intraobserver and interobserver reliability for both lower limbs, Cohen κ and Gwet's AC1 reliability coefficients were calculated with 95% confidence interval and P value of the zero-reliability comparison test. To interpret reliability coefficients, we used the orders of magnitude reported by Landis and Koch.

RESULTS

One hundred forty-four patients (288 limbs) with PLE were included. For intraobserver reliability, agreement range was 0.87-1 with an almost perfect agreement in all staging items of the score for both limbs with the lower limit of the 95% confidence interval ≥80%. Interobserver reliability was overall strong or almost perfect, ranging from 0.67 to 0.97.

CONCLUSIONS

This new scoring system demonstrated excellent intraobserver reliability and a very good interobserver reliability. Lymphoscintigraphy, when performed in a referral center and interpreted by trained nuclear medicine physicians, is a reliable means of investigation in patients with PLE of the lower limbs. This reproducibility advocates for further use of lymphoscintigraphy in multicentric cohorts of PLE patients.

Magnetic resonance lymphangiography: Establishing normal

BACKGROUND

Despite an increased interest in visualizing the lymphatic vessels with magnetic resonance lymphangiography (MRL), little literature is available describing their appearance in nonlymphedematous individuals. To determine lymphatic abnormalities, an understanding of how healthy lymphatic vessels appear and behave needs to be established. Therefore, in this study, MRL of individuals without a history of lymphatic disease was performed.

METHODS

A total of 25 individuals (15 women) underwent MRL of their lower limbs using a 3.0 T Philips magnetic resonance imaging scanner (Philips Medical Systems). The first nine participants were recruited to establish the concentration of gadolinium-based contrast agent (GBCA) to administer, with the remainder imaged before and after interdigital forefoot GBCA injections at the optimized dose. Outcomes, including lymphatic vessel diameter, tortuosity, and frequency of drainage via particular drainage routes, were recorded.

RESULTS

Healthy lymphatic vessels following the anteromedial pathway were routinely observed in post-contrast T1-weighted images (average tortuosity, 1.09 ± 0.03), with an average of 2.16 ± 0.93 lymphatic vessels with a diameter of 2.47 ± 0.50 mm crossing the anterior ankle. In six limbs, vessels following the anterolateral pathways were observed. No vessels traversing the posterior of the legs were seen. In a subset of 10 vessels, the lymphatic signal, measured at the ankle, peaked 29 minutes, 50 seconds ± 9 minutes, 29 seconds after GBCA administration. No lymphatic vessels were observed in T2-weighted images.

CONCLUSIONS

Contrast-enhanced MRL reliably depicts the lymphatic vessels in the legs of healthy controls. Following interdigital contrast injection, anteromedial drainage appears dominant. Quantitative measures related to lymphatic vessel size, tortuosity, and drainage rate are readily obtainable and could be beneficial for detecting even subtle lymphatic impairment.

Profound and selective lymphopaenia in primary lymphatic anomaly patients demonstrates the significance of lymphatic-lymphocyte interactions

Introduction

The lymphatic system has a pivotal role in immune homeostasis. To better understand this, we investigated the impact of Primary Lymphatic Anomalies (PLA) on lymphocyte numbers and phenotype.

Methods

The study comprised (i) a retrospective cohort: 177 PLA subjects from the National Primary Lymphatic Anomaly Register with clinical and laboratory data, and (ii) a prospective cohort: 28 patients with PLA and 20 healthy controls. Patients were subdivided using established phenotypic diagnostic categories and grouped into simplex (localised tissue involvement only) and systemic (involvement of central lymphatics). Further grouping variables included genital involvement and the likelihood of co-existent intestinal lymphangiectasia. Haematology laboratory parameters were analysed in both cohorts. In the prospective cohort, prospective blood samples were analysed by flow cytometry for markers of proliferation, differentiation, activation, skin-homing, and for regulatory (CD4+Foxp3+) T cells (Treg).

Results

In patients with PLA, lymphopaenia was frequent (22% of subjects), affected primarily the CD4+ T cell subset, and was more severe in subjects with systemic versus simplex patterns of disease (36% vs 9% for lymphopaenia; 70% vs 33% for CD4+ cells). B cells, NK cells and monocytes were better conserved (except in GATA2 deficiency characterised by monocytopaenia). Genital oedema and likelihood of concomitant intestinal lymphangiectasia independently predicted CD4+ T cell depletion. Analysing CD4+ and CD8+ T cells by differentiation markers revealed disproportionate depletion of naïve cells, with a skewing towards a more differentiated effector profile. Systemic PLA conditions were associated with: increased expression of Ki67, indicative of recent cell division, in naïve CD4+, but not CD8+ T cells; increased levels of activation in CD4+, but not CD8+ T cells; and an increased proportion of Treg. Skin-homing marker (CCR10, CLA and CCR4) expression was reduced in some patients with simplex phenotypes.

Discussion

Patients with PLA who have dysfunctional lymphatics have a selective reduction in circulating lymphocytes which preferentially depletes naïve CD4+ T cells. The presence of systemic disease, genital oedema, and intestinal lymphangiectasia independently predict CD4 lymphopaenia. The association of this depletion with immune activation and increased circulating Tregs suggests lymphatic-lymphocyte interactions and local inflammatory changes are pivotal in driving immunopathology.

Near-Infrared Imaging of Indocyanine Green Identifies Novel Routes of Lymphatic Drainage from Metacarpophalangeal Joints in Healthy Human Hands

Background: Collecting lymphatic vessel (CLV) dysfunction has been implicated in various diseases, including rheumatoid arthritis (RA). RA patients with active hand arthritis exhibit significantly reduced lymphatic clearance of the web spaces adjacent to the metacarpophalangeal (MCP) joints and a reduction in total and basilic-associated CLVs on the dorsal surface of the hand by near-infrared (NIR) imaging of indocyanine green (ICG). In this pilot study, we assessed direct lymphatic drainage from MCP joints and aimed to visualize the total lymphatic anatomy using novel dual-agent relaxation contrast magnetic resonance lymphography (DARC-MRL) in the upper extremity of healthy human subjects. Methods and Results: Two healthy male subjects >18 years old participated in the study. We performed NIR imaging along with conventional- or DARC-MRL following intradermal web space and intra-articular MCP joint injections. ICG (NIR) or gadolinium (Gd) (MRL) was administered to visualize the CLV anatomy of the upper extremity. Web space draining CLVs were associated with the cephalic side of the antecubital fossa, while MCP draining CLVs were localized to the basilic side of the forearm by near-infrared indocyanine green imaging. The DARC-MRL methods used in this study did not adequately nullify the contrast in the blood vessels, and limited Gd-filled CLVs were identified. Conclusion: MCP joints predominantly drain into basilic CLVs in the forearm, which may explain the reduction in basilic-associated CLVs in the hands of RA patients. Current DARC-MRL techniques show limited identification of healthy lymphatic structures, and further refinement in this technique is necessary. Clinical trial registration number: NCT04046146.

Redefining WILD syndrome: a primary lymphatic dysplasia with congenital multisegmental lymphoedema, cutaneous lymphovascular malformation, CD4 lymphopaenia and warts

BACKGROUND

Primary lymphoedema (PL) syndromes are increasingly recognised as presentations of complex genetic disease, with at least 20 identified causative genes. Recognition of clinical patterns is key to diagnosis, research and therapeutics. The defining criteria for one such clinical syndrome, 'WILD syndrome' (Warts, Immunodeficiency, Lymphoedema and anogenital Dysplasia), have previously depended on a single case report.

METHODS AND RESULTS

We present 21 patients (including the first described case) with similar clinical and immunological phenotypes. All had PL affecting multiple segments, with systemic involvement (intestinal lymphangiectasia/pleural or pericardial effusions) in 70% (n=14/20). Most (n=20, 95%) had a distinctive cutaneous lymphovascular malformation on the upper anterior chest wall. Some (n=10, 48%) also had hyperpigmented lesions resembling epidermal naevi (but probably lymphatic in origin). Warts were common (n=17, 81%) and often refractory. In contrast to the previous case report, anogenital dysplasia was uncommon-only found in two further cases (total n=3, 14%). Low CD4 counts and CD4:CD8 ratios typified the syndrome (17 of 19, 89%), but monocyte counts were universally normal, unlike GATA2 deficiency.

CONCLUSION

WILD syndrome is a previously unrecognised, underdiagnosed generalised PL syndrome. Based on this case series, we redefine WILD as 'Warts, Immunodeficiency, andLymphatic Dysplasia' and suggest specific diagnostic criteria. The essential criterion is congenital multisegmental PL in a 'mosaic' distribution. The major diagnostic features are recurrent warts, cutaneous lymphovascular malformations, systemic involvement (lymphatic dysplasia), genital swelling and CD4 lymphopaenia with normal monocyte counts. The absence of family history suggests a sporadic condition, and the random distribution of swelling implicates mosaic postzygotic mutation as the cause.

Retrograde Lymph Flow in the Lymphatic Vessels in Limb Lymphedema

OBJECTIVE

Retrograde movement of lymph due to damaged and/or incompetent valves in the lymphatic vessels has been considered a pathological feature of lymphedema. This study aimed to determine the prevalence of retrograde lymph flow and the characteristics of patients with this condition using indocyanine green (ICG) lymphography.

METHODS

An audit of 679 patients with upper or lower limb swelling who underwent ICG lymphography was undertaken over a 4-year period. Harvey's technique was applied to identify retrograde flow in the lymph collecting vessel during ICG lymphography. The characteristics of patients with retrograde lymph flow were recorded.

RESULTS

Twenty-one patients (3.7%, lower limb: n=19, upper limb: n=2) were identified as having retrograde flow in lymph collecting vessels out of 566 confirmed lymphedema patients (lower limb: n=275, upper limb: n=291). Of the two patients with upper limb lymphedema, one had a short segment of retrograde lymph flow in the forearm. The other patient with upper limb lymphedema and one patient with lower limb lymphedema were previously diagnosed with Lymphedema-Distichiasis Syndrome. Of the remaining 18 patients with lower limb lymphedema and retrograde lymph flow, nine had initiating insect bites with lymphangitis and three had palpable benign enlarged inguinal lymph nodes evident prior to lower limb swelling onset. None had cancer-related lower limb lymphedema.

CONCLUSIONS

Retrograde lymph flow with valve incompetence in the lymph collecting vessels was a rare finding in upper limb lymphedema and a relatively uncommon in lower limb lymphedema, contradicting conventional understanding of pathological changes in lymphedema. ICG lymphography identified anticipated retrograde lymph flow in two patients with Lymphedema-Distichiasis. In the remaining patients, retrograde lymph flow may have resulted from toxic or asymptomatic lymphangitis but no association with secondary cancer-related lymphedema. These findings have implication for conservative management as well as lymphovenous anastomosis surgery where both ends of a transected lymph collecting vessel would be potential targets for anastomoses.

Digenic Inheritance of a FOXC2 Mutation and Two PIEZO1 Mutations Underlies Congenital Lymphedema in a Multigeneration Family

BACKGROUND

The lymphatic system is essential for maintaining the balance of interstitial fluid in tissues and for returning protein-rich fluids (lymph) to the bloodstream. Congenital lymphatic defects lead to accumulation of lymph in peripheral tissues and body cavities, termed primary lymphedema. To date, only a limited number of individual genes have been identified in association with primary lymphedema. However, variability of age of onset and severity of lymphatic abnormalities within some families suggests that multiple mutations or genes may be responsible, thus hampering efforts to identify individual associated genes.

METHODS

Whole exome sequencing (WES) was performed in 4 members of a large multigeneration family with highly variable lymphedema and followed by Sanger sequencing for identified mutations in 34 additional family members. Genotypes were correlated with clinical and lymphangioscintigraphic phenotypes.

RESULTS

WES uncovered 2 different mechanotransducer PIEZO1 mutations and one FOXC2 transcription factor mutation in various combinations. Sanger sequencing confirmed the presence/absence of the 3 variants in affected and unaffected family members and co-segregation of one or more variants with disease. Genetic profiles did not clearly correlate with the highly variable severity of lymphatic abnormalities.

CONCLUSIONS

WES in lymphedema families can uncover unexpected combinations of several lymphedema-associated mutations. These findings provide essential information for genetic counseling and reveal complex gene interactions in lymphatic developmental pathways. These can offer insights into the complex spectrum of clinical and lymphatic lymphedema phenotypes and potential targets for treatment.

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.

Development and physiological functions of the lymphatic system: insights from human genetic studies of primary lymphedema

Primary lymphedema is a long-term (chronic) condition characterized by tissue lymph retention and swelling that can affect any part of the body, although it usually develops in the arms or legs. Due to the relevant contribution of the lymphatic system to human physiology, while this review mainly focuses on the clinical and physiological aspects related to the regulation of fluid homeostasis and edema, clinicians need to know that the impact of lymphatic dysfunction with a genetic origin can be wide ranging. Lymphatic dysfunction can affect immune function so leading to infection; it can influence cancer development and spread, and it can determine fat transport so impacting on nutrition and obesity. Genetic studies and the development of imaging techniques for the assessment of lymphatic function have enabled the recognition of primary lymphedema as a heterogenic condition in terms of genetic causes and disease mechanisms. In this review, the known biological functions of several genes crucial to the development and function of the lymphatic system are used as a basis for understanding normal lymphatic biology. The disease conditions originating from mutations in these genes are discussed together with a detailed clinical description of the phenotype and the up-to-date knowledge in terms of disease mechanisms acquired from in vitro and in vivo research models.

PIEZO1-gene gain-of-function mutations with lower limb lymphedema onset in an adult: Clinical, scintigraphic, and noncontrast magnetic resonance lymphography findings

Primary lymphedema, a rare disease, has a genetic cause in ~40% of patients. Recently, loss-of-function mutations in PIEZO1, which encodes the mechanotransducer protein PIEZO1, were described as causing primary lymphedema, when gain-of-function PIEZO1 mutations were attributed to dehydrated hereditary stomatocytosis type-1 (DHS), a dominant red cell hemolytic disorder, with ~20% of patients having perinatal edema. Lymphedema was diagnosed in a 36-year-old man from a three-generation DHS family, with a PIEZO1-allele harboring 3 missense mutations in cis. Four affected family members had severe fetal and neonatal edema, most severe in the proband, whose generalized edema with prevailing ascites resolved after 8 months. Our patient's intermittent lower limb-lymphedema episodes during hot periods appeared at puberty; they became persistent and bilateral at age 32. Clinical Stemmer's sign confirmed lymphedema. Lower leg lymphoscintigraphy showed substantial dermal backflow in both calves, predominantly on the right. Noncontrast magnetic resonance lymphography showed bilateral lower limb lymphedema, dilated dysplastic lymphatic iliac, and inguinal trunks. Exome-sequencing analysis identified no additional pathogenic variation in primary lymphedema-associated genes. This is the first description of well-documented lymphedema in an adult with PIEZO1-DHS. The pathophysiology of PIEZO1-associated primary lymphedema is poorly understood. Whether it infers overlapping phenotypes or different mechanisms of gain- and loss-of-function PIEZO1 mutations deserves further investigation.

Advances in Lymphedema

Lymphedema is a common, complex, and inexplicably underappreciated human disease. Despite a history of relative neglect by health care providers and by governmental health care agencies, the last decade has seen an explosive growth of insights into, and approaches to, the problem of human lymphedema. The current review highlights the significant advances that have occurred in the investigative and clinical approaches to lymphedema, particularly over the last decade. This review summarizes the progress that has been attained in the realms of genetics, lymphatic imaging, and lymphatic surgery. Newer molecular insights are explored, along with their relationship to future molecular therapeutics. Growing insights into the relationships among lymphedema, obesity, and other comorbidities are important to consider in current and future responses to patients with lymphedema.

Janus-faced EPHB4-associated disorders: novel pathogenic variants and unreported intrafamilial overlapping phenotypes

Purpose

Several clinical phenotypes including fetal hydrops, central conducting lymphatic anomaly or capillary malformations with arteriovenous malformations 2 (CM-AVM2) have been associated with EPHB4 (Ephrin type B receptor 4) variants, demanding new approaches for deciphering pathogenesis of novel variants of uncertain significance (VUS) identified in EPHB4, and for the identification of differentiated disease mechanisms at the molecular level.

Methods

Ten index cases with various phenotypes, either fetal hydrops, CM-AVM2, or peripheral lower limb lymphedema, whose distinct clinical phenotypes are described in detail in this study, presented with a variant in EPHB4. In vitro functional studies were performed to confirm pathogenicity.

Results

Pathogenicity was demonstrated for six of the seven novel EPHB4 VUS investigated. A heterogeneity of molecular disease mechanisms was identified, from loss of protein production or aberrant subcellular localization to total reduction of the phosphorylation capability of the receptor. There was some phenotype–genotype correlation; however, previously unreported intrafamilial overlapping phenotypes such as lymphatic-related fetal hydrops (LRFH) and CM-AVM2 in the same family were observed.

Conclusion

This study highlights the usefulness of protein expression and subcellular localization studies to predict EPHB4 variant pathogenesis. Our accurate clinical phenotyping expands our interpretation of the Janus-faced spectrum of EPHB4-related disorders, introducing the discovery of cases with overlapping phenotypes.