Indocyanine green lymphography as novel tool to assess lymphatics in patients with lipedema

Proposed Framework for Research Case Definitions of Lipedema

Background: Our aim is to propose a framework for the development of a research case definition of lipedema, based on current available literature and those observations that can be applied to future lipedema research with the intent to standardize and strengthen the scientific evidence base. Methods and Results: We conducted a narrative review of the literature, and identified consensus characteristics and disputed characteristics that could be included in a research case definition of lipedema. After considering the strength of the evidence and how each characteristic might be measured in a research study, we recommended an approach for the development of a research case definition of lipedema that would be based on consideration of five agreed-upon characteristics, and five disputed, or less substantiated, characteristics as additional evidence to enhance specificity. Conclusions: We present a case definition framework for lipedema drawn from the scientific literature that can be applied to future studies on lipedema. Utilizing this framework should help to increase the sensitivity and specificity of case definition and provide an opportunity for meta-analysis of clinical studies and facilitate future research intercomparisons.

Effect of Physical Therapy on Circumference Measurement and Extremity Volume in Patients Suffering from Lipedema with Secondary Lymphedema

Background: Lipedema is a chronic and progressive disease. Many complications can occur if the disease is not treated. The most important of these complications is lipedema with secondary lymphedema. There are very few publications about lipedema with secondary lymphedema. The aim of this study is to investigate the effect of physical therapy on lower extremity circumference and volume in patients suffering from lipedema with secondary lymphedema. Methods and Results: All patients received pneumatic compression and complex decongestive therapy (CDT). Perometer measurement was made at five distinct points. Fifteen patients were included in the study. It was seen that significant reduction was found in the circumference of three of the five points of measurements performed in the left leg, whereas significant reduction was found in the circumference of four of the five points of measurements performed in the right leg. Also, there was a decrease in the extremity volume in both legs. Conclusion: Combined application of CDT and pneumatic compression in patients suffering from lipedema with secondary lymphedema is an effective treatment method in reducing lower extremity volume and circumference measurement.

Diagnostic imaging in lipedema: A systematic review

BACKGROUND

Diagnosing lipedema remains a challenge due to its heterogeneous presentation, co-existing diseases, and the lack of objective diagnostic imaging.

OBJECTIVE

This systematic review aims to outline the currently available diagnostic imaging methods to characterize lipedema in the legs along with their diagnostic performance.

METHODS

PubMed, Embase, Google Scholar, Scopus, and Web of Science were searched. The quality assessment of diagnostic accuracy studies (QUADAS) tool was used for quality assessment.

RESULTS

Thirty-two studies describing a total of 1154 patients with lipedema were included for final analysis. Features for lipedema have been defined using ultrasound (increased subcutaneous adipose tissue), lymphoscintigraphy (slowing of the lymphatic flow and a frequent asymmetry between the lower extremities), computed tomography (symmetrical bilateral soft tissue enlargement without either skin thickening or subcutaneous edema), magnetic resonance imaging (increased subcutaneous adipose tissue), MR lymphangiography (enlarged lymphatic vessels up to a diameter of 2 mm), and dual-energy X-ray absorptiometry (fat mass in the legs adjusted for body mass index (BMI) ≥ 0.46 or fat mass in the legs adjusted for total fat mass ≥ 0.384).

CONCLUSION

The diagnostic performance of currently available imaging modalities for assessing lipedema is limited. Prospective studies are needed to evaluate and compare the diagnostic performance of each imaging modality. Imaging techniques focusing on the pathogenesis of the disease are needed.

[Searching for Evidence: A Systematic Review of the Pathology of Lipoedema]

BACKGROUND

Lipoedema is a symmetrically localised, painful hypertrophy of subcutaneous adipose tissue in the extremities with marked disproportion to the trunk, and almost exclusively affects females. Despite being first described over 80 years ago, the aetiology and pathogenesis of the disease are largely unknown and are currently the subject of intensive research efforts.

METHODS

To summarise the current evidence-based literature on the cellular pathologies and aetiology of lipoedema, a PRISMA-based systematic review was conducted within the National Library of Medicine and Cochrane databases.

RESULTS

A total of 53 studies were identified and included in this review. The results were classified and summarised into categories.

CONCLUSION

Although there has been a significant increase in research activity and recent publication of extensive studies with a histological and molecular genetic focus, the fundamental aetiology and pathology of lipoedema remains largely unclear. The current data shows discrepancies across studies, particularly with regard to the "oedematous" component of lipoedema. The frequently present comorbidities "lymphoedema" and "obesity", primarily in advanced stages of lipoedema, complicate the diagnostic differentiation and clear definition of study cohorts in scientific research.

Body mass index vs. waist-to-height-ratio in patients with lipohyperplasia dolorosa (vulgo lipedema)

BACKGROUND

Lipedema, also known as lipohyperplasia dolorosa (LiDo), is a painful condition affecting women, causing a disproportionate accumulation of subcutaneous adipose tissue in the extremities. It carries a lower risk of diabetes and cardio-metabolic dysfunctions compared to obesity, but coincident obesity can complicate diagnosis and treatment.

PATIENTS AND METHODS

This retrospective study included 607 female LiDo patients, ≥ 18 years, stage 1-3, from Germany, the UK, and Spain. Data were collected as part of the standard initial assessment for LiDo patients.

RESULTS

Based on waist-to-height-ratio (WHtR), 15.2% of patients were underweight, 45.5% normal weight, 22.1% overweight and 17.3% obese. There was a significant association between WHtR category and age group. Body mass index (BMI) is often overestimated, leading to misdiagnosis of obesity.

CONCLUSIONS

The use of BMI also affects the recent decision of the German Federal Joint Committee on the reimbursement of liposuction costs by health insurance funds. Patients with BMI of more than 40 kg/m2 are excluded from cost coverage, and those with BMI between 35 kg/m2 and 40 kg/m2 must first receive conservative obesity therapy. In conclusion, the sole use of BMI in lipedema is unreliable and, in contrast to WHtR, leads to inaccurate diagnoses overestimating overweight and obesity.

In Vivo Dynamic and Static Analysis of Lymphatic Dysfunction in Lymphedema Using Near-Infrared Fluorescence Indocyanine Green Lymphangiography

BACKGROUND

Near-infrared fluorescence indocyanine green lymphangiography, a primary modality for detecting lymphedema, which is a disease due to lymphatic obstruction, enables real-time observations of lymphatics and reveals not only the spatial distribution of drainage (static analysis) but also information on the lymphatic contraction (dynamic analysis).

METHODS

We have produced total lymphatic obstruction in the upper limbs of 18 Sprague-Dawley rats through the dissection of proximal (brachial and axillary) lymph nodes and 20-Gy radiation (dissection limbs). After the model formation for 1 week, 9 animal models were observed for 6 weeks using near-infrared fluorescence indocyanine green lymphangiography by injecting 6-μL ICG-BSA (indocyanine green-bovine serum albumin) solution of 20-μg/mL concentration. The drainage pattern and leakage of lymph fluid were evaluated and time-domain signals of lymphatic contraction were observed in the distal lymphatic vessels. The obtained signals were converted to frequency-domain spectrums using signal processing.

RESULTS

The results of both static and dynamic analyses proved to be effective in accurately identifying the extent of lymphatic disruption in the dissection limbs. The static analysis showed abnormal drainage patterns and increased leakage of lymph fluid to the periphery of the vessels compared with the control (normal) limbs. Meanwhile, the waveforms were changed and the contractile signal frequency increased by 58% in the dynamic analysis. Specifically, our findings revealed that regular lymphatic contractions, observed at a frequency range of 0.08 to 0.13 Hz in the control limbs, were absent in the dissection limbs. The contractile regularity was not fully restored for the follow-up period, indicating a persistent lymphatic obstruction.

CONCLUSIONS

The dynamic analysis could detect the abnormalities of lymphatic circulation by observing the characteristics of signals, and it provided additional evaluation indicators that cannot be provided by the static analysis. Our findings may be useful for the early detection of the circulation problem as a functional evaluation indicator of the lymphatic system.

Protein@Cyanine-Based NIR-II Lymphography Enables the Supersensitive Visualization of Lymphedema and Tumor Lymphatic Metastasis

Visualization of the lymphatic system is clinically indispensable for the diagnosis and/or treatment of lymphatic diseases. Although indocyanine green (ICG) lymphography becomes an alternate imaging modality compared to traditional lymphoscintigraphy, it is still far from ideal due to the insufficient detection depth and low spatiotemporal resolution. Herein, protein@cyanine probes are rationally developed to solve the limitations of the current near-infrared-I (NIR-I) lymphography. The protein@cyanine probes are synthesized following a chlorine-containing dye-labeling strategy based on structure-selectivity (facile covalent binding between the dye and protein with a 1:1 molar ratio). As expected, the probes display exceptional NIR-II imaging ability with much-improved imaging contrast/resolution and controllable pharmacokinetics, superior to the clinical ICG. The protein@cyanine probes locate lymph nodes and delineate lymphatic vessels with super-high sensitivity and signal-to-background ratio, enabling real-time diagnosing lymphatic diseases such as lymphedema and tumor lymphatic metastasis. In particular, the NIR-II lymphography provides an opportunity to discover the disparate morbidity rate of primary lymphedema in different types of mice. Given the fact of lacking clinically transferable NIR-II probes, this work not only provides a promising strategy for enriching of the current library of NIR-II probes, but also promotes the clinical translation of NIR-II lymphography technology.

Body-Mass-Index vs. Taille-zu-Größe-Verhältnis bei Patientinnen mit Lipohyperplasia dolorosa (vulgo Lipödem)

Hintergrund

Das Lipödem, auch Lipohyperplasia dolorosa (LiDo) genannt, ist eine schmerzhafte Erkrankung von Frauen, die zu einer unverhältnismäßigen Ansammlung von subkutanem Fettgewebe in den Extremitäten führt. Das Risiko für Diabetes und kardiometabolische Störungen ist im Vergleich zur Adipositas geringer, doch kann eine gleichzeitige Adipositas die Diagnose und Behandlung erschweren.

Patientinnen und Methodik

Diese retrospektive Studie umfasste 607 LiDo‐Patientinnen, ≥ 18 Jahre, Stadium 1–3, aus Deutschland, dem Vereinigten Königreich und Spanien. Die Daten wurden im Rahmen der Standard‐Erstuntersuchung erhoben.

Ergebnisse

Basierend auf dem Verhältnis von Taillenumfang zu Körpergröße (Waist‐to‐Height‐Ratio; WHtR) waren 15,2% der Patientinnen untergewichtig, 45,5% normalgewichtig, 22,1% übergewichtig und 17,3% adipös. Es bestand ein signifikanter Zusammenhang zwischen der WHtR‐Kategorie und der Altersgruppe. Der Body‐Mass‐Index (BMI) wird häufig überschätzt, was zu Fehldiagnosen von Fettleibigkeit führt.

Schlussfolgerungen

Die Verwendung des BMI hat auch Auswirkungen auf die jüngste Entscheidung des Gemeinsamen Bundesausschusses über die Kostenerstattung von Fettabsaugungen durch die Krankenkassen. Patientinnen mit einem BMI von über 40 kg/m2 sind von der Kostenübernahme ausgeschlossen, und Patientinnen mit einem BMI zwischen 35 kg/m2 und 40 kg/m2 müssen zunächst eine konservative Adipositastherapie erhalten. Die alleinige Verwendung des BMI bei Lipödemen ist unzuverlässig und führt im Gegensatz zum WHtR zu ungenauen Diagnosen, die Übergewicht und Adipositas überbewerten.

Differentiation of lipoedema from bilateral lower limb lymphoedema by imaging assessment of indocyanine green lymphography

Lipoedema is characterized by disproportionate painful fat accumulation mostly in the lower limbs. The presence of lymphoedema in lipoedema remains controversial. This study aimed to assess the presence or absence of lymphoedema in the lower limbs of women with lipoedema using indocyanine green (ICG) lymphography. A cross-sectional retrospective study was undertaken in women with a clinical diagnosis of lipoedema whose lower limbs were examined with ICG lymphography. MD Anderson Cancer Center (MDACC) ICG staging was used to determine lymphoedema presence and severity. Patient characteristics, ICG lymphography findings, Stemmer sign, body mass index, waist-to-hip ratio, limb volume and bioimpedance spectroscopy measures were recorded. Forty women with lipoedema underwent ICG lymphography for the lower limbs from January 2018 to July 2022. Thirty-four women (85.0%) were determined by ICG lymphography as MDACC ICG Stage 0 representing normal lymphatics. Of the six women who demonstrated dermal backflow on ICG lymphography, all were determined as ICG Stage 1, four had localized traumatic dermal backflow area at their ankles, one had previously diagnosed with primary lymphoedema and one was classified as lipoedema stage 4. ICG lymphography findings suggested the absence of lymphoedema in a clear majority of women with lower limb lipoedema.

Functioning of People with Lipoedema According to All Domains of the International Classification of Functioning, Disability and Health: A Scoping Review

Lipoedema is a painful non-pitting diffuse "fatty" swelling, usually confined to the legs, that occurs mainly in women. This scoping review aimed to provide an overview of the available research on the functioning of people with lipoedema, according to the International Classification of Functioning, Disability and Health (ICF) framework. Relevant publications and gray literature were retrieved until October 2022. The results sections of each publication were organized using a thematic framework approach. All included studies reported at least one outcome fitting within the domains of body functions and body structures, with most studies focusing on the categories of "sensation of pain", "immunological system functions", and "weight maintenance functions". The ICF domains of activities and participation and environmental factors were mentioned in a small number of the included studies (17 and 13%, respectively), while the domain of personal factors was studied in half of the included studies. In conclusion, the emphasis of lipoedema research is on its description from a disorder-oriented point of view in the form of body functions and body structures, with a lack of information about the other domains of functioning.

Lymphoscintigraphic alterations in lower limbs in women with lipedema in comparison to women with overweight/obesity

Introduction: Lipedema is a bilateral enlargement of the legs due to abnormal depositions of subcutaneous fat. Recent studies using lymphoscintigraphy documented that lipedema associates with lymphatic alterations. It is still not known, whether non-lipedema obesity also leads to similar lymphoscintigraphic changes within lower legs. Clinically, both, lipedema and obesity may progress to secondary lymphedema. The aim of the study was to evaluate lymphoscintigraphy of lower limbs in women with lipedema in comparison to overweight/obese women. Methods: 51 women (in the mean age of 43.3 ± 13.56) with the diagnosis of lipedema and 31 women (in the mean age of 44.7 ± 13.48) with overweight/obesity were enrolled into the study. Women in both study groups had no clinical signs of lymphedema. The groups were matched by mean volume of their legs, calculated using the formula for a truncated cone. Lymphoscintigraphy was evaluated in every women qualitatively. Body composition parameters were assessed using bioelectric impedance analysis (BIA). Results: Lymphoscintigraphic alterations within lower extremities were similar in both, lipedema and overweight/obese groups and were present in majority of women in both study groups. The most common lymphoscintigraphic alteration in both groups were additional lymphatic vessels (in the lipedema group observed in 76.5% of patients and in the overweight/obesity group - in 93.5%). Visualization of popliteal lymph nodes and dermal backflow were observed respectively in 33% and in 5.9% in the group with lipedema and in 45.2% and in 9.7% in the overweight/obesity group. There were significant relationships between severity of lymphoscintigraphic alterations and weight, lean body mass (LBM), total body water (TBW), volume of both legs and thigh circumference in the lipedema group. Such relationships were absent in the overweight/obesity group. Discussion: Our study indicates that lymphatic alterations are present before development to clinically visible secondary lymphedema in both conditions, lipedema and overweight/obesity. In majority of women from both study groups they indicate rather an overload of the lymphatic system than insufficiency. Lymphoscintigraphic alterations are similar in both groups, therefore, lymphoscintigraphy is not a diagnostic tool that might distinguish lipedema from overweight/obesity.

Lymphatic function and anatomy in early stages of lipedema

OBJECTIVE

Lipedema is an inflammatory subcutaneous adipose tissue disease that develops in women and may progress to lipolymphedema, a condition similar to lymphedema, in which lymphatic dysfunction results in irresolvable edema. Because it has been shown that dilated lymphatic vessels, impaired pumping, and dermal backflow are associated with presymptomatic, cancer-acquired lymphedema, this study sought to understand whether these abnormal lymphatic characteristics also characterize early stages of lipedema prior to lipolymphedema development.

METHODS

In a pilot study of 20 individuals with Stage I or II lipedema who had not progressed to lipolymphedema, lymphatic vessel anatomy and function in upper and lower extremities were assessed by near-infrared fluorescence lymphatic imaging and compared with that of a control population of similar age and BMI.

RESULTS

These studies showed that, although lower extremity lymphatic vessels were dilated and showed intravascular pooling, the propulsion rates significantly exceeded those of control individuals. Upper extremity lymphatics of individuals with lipedema were unremarkable. In contrast to individuals with lymphedema, individuals with Stage I and II lipedema did not exhibit dermal backflow.

CONCLUSIONS

These results suggest that, despite the confusion in the diagnoses between lymphedema and lipedema, their etiologies differ, with lipedema associated with lymphatic vessel dilation but not lymphatic dysfunction.

Current Mechanistic Understandings of Lymphedema and Lipedema: Tales of Fluid, Fat, and Fibrosis

Lymphedema and lipedema are complex diseases. While the external presentation of swollen legs in lower-extremity lymphedema and lipedema appear similar, current mechanistic understandings of these diseases indicate unique aspects of their underlying pathophysiology. They share certain clinical features, such as fluid (edema), fat (adipose expansion), and fibrosis (extracellular matrix remodeling). Yet, these diverge on their time course and known molecular regulators of pathophysiology and genetics. This divergence likely indicates a unique route leading to interstitial fluid accumulation and subsequent inflammation in lymphedema versus lipedema. Identifying disease mechanisms that are causal and which are merely indicative of the condition is far more explored in lymphedema than in lipedema. In primary lymphedema, discoveries of genetic mutations link molecular markers to mechanisms of lymphatic disease. Much work remains in this area towards better risk assessment of secondary lymphedema and the hopeful discovery of validated genetic diagnostics for lipedema. The purpose of this review is to expose the distinct and shared (i) clinical criteria and symptomatology, (ii) molecular regulators and pathophysiology, and (iii) genetic markers of lymphedema and lipedema to help inform future research in this field.